Merge branch 'for-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue changes from Tejun Heo:
 "A lot of reorganization is going on mostly to prepare for worker pools
  with custom attributes so that workqueue can replace custom pool
  implementations in places including writeback and btrfs and make CPU
  assignment in crypto more flexible.

  workqueue evolved from purely per-cpu design and implementation, so
  there are a lot of assumptions regarding being bound to CPUs and even
  unbound workqueues are implemented as an extension of the model -
  workqueues running on the special unbound CPU.  Bulk of changes this
  round are about promoting worker_pools as the top level abstraction
  replacing global_cwq (global cpu workqueue).  At this point, I'm
  fairly confident about getting custom worker pools working pretty soon
  and ready for the next merge window.

  Lai's patches are replacing the convoluted mb() dancing workqueue has
  been doing with much simpler mechanism which only depends on
  assignment atomicity of long.  For details, please read the commit
  message of 0b3dae68 ("workqueue: simplify is-work-item-queued-here
  test").  While the change ends up adding one pointer to struct
  delayed_work, the inflation in percentage is less than five percent
  and it decouples delayed_work logic a lot more cleaner from usual work
  handling, removes the unusual memory barrier dancing, and allows for
  further simplification, so I think the trade-off is acceptable.

  There will be two more workqueue related pull requests and there are
  some shared commits among them.  I'll write further pull requests
  assuming this pull request is pulled first."

* 'for-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: (37 commits)
  workqueue: un-GPL function delayed_work_timer_fn()
  workqueue: rename cpu_workqueue to pool_workqueue
  workqueue: reimplement is_chained_work() using current_wq_worker()
  workqueue: fix is_chained_work() regression
  workqueue: pick cwq instead of pool in __queue_work()
  workqueue: make get_work_pool_id() cheaper
  workqueue: move nr_running into worker_pool
  workqueue: cosmetic update in try_to_grab_pending()
  workqueue: simplify is-work-item-queued-here test
  workqueue: make work->data point to pool after try_to_grab_pending()
  workqueue: add delayed_work->wq to simplify reentrancy handling
  workqueue: make work_busy() test WORK_STRUCT_PENDING first
  workqueue: replace WORK_CPU_NONE/LAST with WORK_CPU_END
  workqueue: post global_cwq removal cleanups
  workqueue: rename nr_running variables
  workqueue: remove global_cwq
  workqueue: remove worker_pool->gcwq
  workqueue: replace for_each_worker_pool() with for_each_std_worker_pool()
  workqueue: make freezing/thawing per-pool
  workqueue: make hotplug processing per-pool
  ...

include/linux/async.h

@@ -52,4 +52,5 @@ extern void async_synchronize_full_domain(struct async_domain *domain);
 extern void async_synchronize_cookie(async_cookie_t cookie);
 extern void async_synchronize_cookie_domain(async_cookie_t cookie,
 					    struct async_domain *domain);
+extern bool current_is_async(void);
 #endif

include/linux/workqueue.h

@@ -27,7 +27,7 @@ void delayed_work_timer_fn(unsigned long __data);
 enum {
 	WORK_STRUCT_PENDING_BIT	= 0,	/* work item is pending execution */
 	WORK_STRUCT_DELAYED_BIT	= 1,	/* work item is delayed */
-	WORK_STRUCT_CWQ_BIT	= 2,	/* data points to cwq */
+	WORK_STRUCT_PWQ_BIT	= 2,	/* data points to pwq */
 	WORK_STRUCT_LINKED_BIT	= 3,	/* next work is linked to this one */
 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 	WORK_STRUCT_STATIC_BIT	= 4,	/* static initializer (debugobjects) */
@@ -40,7 +40,7 @@ enum {
 
 	WORK_STRUCT_PENDING	= 1 << WORK_STRUCT_PENDING_BIT,
 	WORK_STRUCT_DELAYED	= 1 << WORK_STRUCT_DELAYED_BIT,
-	WORK_STRUCT_CWQ		= 1 << WORK_STRUCT_CWQ_BIT,
+	WORK_STRUCT_PWQ		= 1 << WORK_STRUCT_PWQ_BIT,
 	WORK_STRUCT_LINKED	= 1 << WORK_STRUCT_LINKED_BIT,
 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 	WORK_STRUCT_STATIC	= 1 << WORK_STRUCT_STATIC_BIT,
@@ -57,29 +57,36 @@ enum {
 
 	/* special cpu IDs */
 	WORK_CPU_UNBOUND	= NR_CPUS,
-	WORK_CPU_NONE		= NR_CPUS + 1,
-	WORK_CPU_LAST		= WORK_CPU_NONE,
+	WORK_CPU_END		= NR_CPUS + 1,
 
 	/*
-	 * Reserve 7 bits off of cwq pointer w/ debugobjects turned
-	 * off.  This makes cwqs aligned to 256 bytes and allows 15
-	 * workqueue flush colors.
+	 * Reserve 7 bits off of pwq pointer w/ debugobjects turned off.
+	 * This makes pwqs aligned to 256 bytes and allows 15 workqueue
+	 * flush colors.
 	 */
 	WORK_STRUCT_FLAG_BITS	= WORK_STRUCT_COLOR_SHIFT +
 				  WORK_STRUCT_COLOR_BITS,
 
-	/* data contains off-queue information when !WORK_STRUCT_CWQ */
+	/* data contains off-queue information when !WORK_STRUCT_PWQ */
 	WORK_OFFQ_FLAG_BASE	= WORK_STRUCT_FLAG_BITS,
 
 	WORK_OFFQ_CANCELING	= (1 << WORK_OFFQ_FLAG_BASE),
 
+	/*
+	 * When a work item is off queue, its high bits point to the last
+	 * pool it was on.  Cap at 31 bits and use the highest number to
+	 * indicate that no pool is associated.
+	 */
 	WORK_OFFQ_FLAG_BITS	= 1,
-	WORK_OFFQ_CPU_SHIFT	= WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
+	WORK_OFFQ_POOL_SHIFT	= WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
+	WORK_OFFQ_LEFT		= BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT,
+	WORK_OFFQ_POOL_BITS	= WORK_OFFQ_LEFT <= 31 ? WORK_OFFQ_LEFT : 31,
+	WORK_OFFQ_POOL_NONE	= (1LU << WORK_OFFQ_POOL_BITS) - 1,
 
 	/* convenience constants */
 	WORK_STRUCT_FLAG_MASK	= (1UL << WORK_STRUCT_FLAG_BITS) - 1,
 	WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
-	WORK_STRUCT_NO_CPU	= (unsigned long)WORK_CPU_NONE << WORK_OFFQ_CPU_SHIFT,
+	WORK_STRUCT_NO_POOL	= (unsigned long)WORK_OFFQ_POOL_NONE << WORK_OFFQ_POOL_SHIFT,
 
 	/* bit mask for work_busy() return values */
 	WORK_BUSY_PENDING	= 1 << 0,
@@ -95,13 +102,16 @@ struct work_struct {
 #endif
 };
 
-#define WORK_DATA_INIT()	ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU)
+#define WORK_DATA_INIT()	ATOMIC_LONG_INIT(WORK_STRUCT_NO_POOL)
 #define WORK_DATA_STATIC_INIT()	\
-	ATOMIC_LONG_INIT(WORK_STRUCT_NO_CPU | WORK_STRUCT_STATIC)
+	ATOMIC_LONG_INIT(WORK_STRUCT_NO_POOL | WORK_STRUCT_STATIC)
 
 struct delayed_work {
 	struct work_struct work;
 	struct timer_list timer;
+
+	/* target workqueue and CPU ->timer uses to queue ->work */
+	struct workqueue_struct *wq;
 	int cpu;
 };
 
@@ -426,7 +436,6 @@ extern bool cancel_delayed_work_sync(struct delayed_work *dwork);
 extern void workqueue_set_max_active(struct workqueue_struct *wq,
 				     int max_active);
 extern bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq);
-extern unsigned int work_cpu(struct work_struct *work);
 extern unsigned int work_busy(struct work_struct *work);
 
 /*

include/trace/events/workqueue.h

@@ -27,7 +27,7 @@ DECLARE_EVENT_CLASS(workqueue_work,
 /**
  * workqueue_queue_work - called when a work gets queued
  * @req_cpu:	the requested cpu
- * @cwq:	pointer to struct cpu_workqueue_struct
+ * @pwq:	pointer to struct pool_workqueue
  * @work:	pointer to struct work_struct
  *
  * This event occurs when a work is queued immediately or once a
@@ -36,10 +36,10 @@ DECLARE_EVENT_CLASS(workqueue_work,
  */
 TRACE_EVENT(workqueue_queue_work,
 
-	TP_PROTO(unsigned int req_cpu, struct cpu_workqueue_struct *cwq,
+	TP_PROTO(unsigned int req_cpu, struct pool_workqueue *pwq,
 		 struct work_struct *work),
 
-	TP_ARGS(req_cpu, cwq, work),
+	TP_ARGS(req_cpu, pwq, work),
 
 	TP_STRUCT__entry(
 		__field( void *,	work	)
@@ -52,9 +52,9 @@ TRACE_EVENT(workqueue_queue_work,
 	TP_fast_assign(
 		__entry->work		= work;
 		__entry->function	= work->func;
-		__entry->workqueue	= cwq->wq;
+		__entry->workqueue	= pwq->wq;
 		__entry->req_cpu	= req_cpu;
-		__entry->cpu		= cwq->pool->gcwq->cpu;
+		__entry->cpu		= pwq->pool->cpu;
 	),
 
 	TP_printk("work struct=%p function=%pf workqueue=%p req_cpu=%u cpu=%u",

kernel/async.c

@@ -57,6 +57,8 @@ asynchronous and synchronous parts of the kernel.
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 
+#include "workqueue_internal.h"
+
 static async_cookie_t next_cookie = 1;
 
 #define MAX_WORK	32768
@@ -353,3 +355,15 @@ void async_synchronize_cookie(async_cookie_t cookie)
 	async_synchronize_cookie_domain(cookie, &async_running);
 }
 EXPORT_SYMBOL_GPL(async_synchronize_cookie);
+
+/**
+ * current_is_async - is %current an async worker task?
+ *
+ * Returns %true if %current is an async worker task.
+ */
+bool current_is_async(void)
+{
+	struct worker *worker = current_wq_worker();
+
+	return worker && worker->current_func == async_run_entry_fn;
+}

kernel/sched/core.c

@@ -83,7 +83,7 @@
 #endif
 
 #include "sched.h"
-#include "../workqueue_sched.h"
+#include "../workqueue_internal.h"
 #include "../smpboot.h"
 
 #define CREATE_TRACE_POINTS

kernel/workqueue.c

@@ -41,32 +41,31 @@
 #include <linux/debug_locks.h>
 #include <linux/lockdep.h>
 #include <linux/idr.h>
+#include <linux/hashtable.h>
 
-#include "workqueue_sched.h"
+#include "workqueue_internal.h"
 
 enum {
 	/*
-	 * global_cwq flags
+	 * worker_pool flags
 	 *
-	 * A bound gcwq is either associated or disassociated with its CPU.
+	 * A bound pool is either associated or disassociated with its CPU.
 	 * While associated (!DISASSOCIATED), all workers are bound to the
 	 * CPU and none has %WORKER_UNBOUND set and concurrency management
 	 * is in effect.
 	 *
 	 * While DISASSOCIATED, the cpu may be offline and all workers have
 	 * %WORKER_UNBOUND set and concurrency management disabled, and may
-	 * be executing on any CPU.  The gcwq behaves as an unbound one.
+	 * be executing on any CPU.  The pool behaves as an unbound one.
 	 *
 	 * Note that DISASSOCIATED can be flipped only while holding
-	 * assoc_mutex of all pools on the gcwq to avoid changing binding
-	 * state while create_worker() is in progress.
+	 * assoc_mutex to avoid changing binding state while
+	 * create_worker() is in progress.
 	 */
-	GCWQ_DISASSOCIATED	= 1 << 0,	/* cpu can't serve workers */
-	GCWQ_FREEZING		= 1 << 1,	/* freeze in progress */
-
-	/* pool flags */
 	POOL_MANAGE_WORKERS	= 1 << 0,	/* need to manage workers */
 	POOL_MANAGING_WORKERS   = 1 << 1,       /* managing workers */
+	POOL_DISASSOCIATED	= 1 << 2,	/* cpu can't serve workers */
+	POOL_FREEZING		= 1 << 3,	/* freeze in progress */
 
 	/* worker flags */
 	WORKER_STARTED		= 1 << 0,	/* started */
@@ -79,11 +78,9 @@ enum {
 	WORKER_NOT_RUNNING	= WORKER_PREP | WORKER_UNBOUND |
 				  WORKER_CPU_INTENSIVE,
 
-	NR_WORKER_POOLS		= 2,		/* # worker pools per gcwq */
+	NR_STD_WORKER_POOLS	= 2,		/* # standard pools per cpu */
 
 	BUSY_WORKER_HASH_ORDER	= 6,		/* 64 pointers */
-	BUSY_WORKER_HASH_SIZE	= 1 << BUSY_WORKER_HASH_ORDER,
-	BUSY_WORKER_HASH_MASK	= BUSY_WORKER_HASH_SIZE - 1,
 
 	MAX_IDLE_WORKERS_RATIO	= 4,		/* 1/4 of busy can be idle */
 	IDLE_WORKER_TIMEOUT	= 300 * HZ,	/* keep idle ones for 5 mins */
@@ -111,48 +108,24 @@ enum {
  * P: Preemption protected.  Disabling preemption is enough and should
  *    only be modified and accessed from the local cpu.
  *
- * L: gcwq->lock protected.  Access with gcwq->lock held.
+ * L: pool->lock protected.  Access with pool->lock held.
  *
- * X: During normal operation, modification requires gcwq->lock and
- *    should be done only from local cpu.  Either disabling preemption
- *    on local cpu or grabbing gcwq->lock is enough for read access.
- *    If GCWQ_DISASSOCIATED is set, it's identical to L.
+ * X: During normal operation, modification requires pool->lock and should
+ *    be done only from local cpu.  Either disabling preemption on local
+ *    cpu or grabbing pool->lock is enough for read access.  If
+ *    POOL_DISASSOCIATED is set, it's identical to L.
  *
  * F: wq->flush_mutex protected.
  *
  * W: workqueue_lock protected.
  */
 
-struct global_cwq;
-struct worker_pool;
-
-/*
- * The poor guys doing the actual heavy lifting.  All on-duty workers
- * are either serving the manager role, on idle list or on busy hash.
- */
-struct worker {
-	/* on idle list while idle, on busy hash table while busy */
-	union {
-		struct list_head	entry;	/* L: while idle */
-		struct hlist_node	hentry;	/* L: while busy */
-	};
-
-	struct work_struct	*current_work;	/* L: work being processed */
-	struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */
-	struct list_head	scheduled;	/* L: scheduled works */
-	struct task_struct	*task;		/* I: worker task */
-	struct worker_pool	*pool;		/* I: the associated pool */
-	/* 64 bytes boundary on 64bit, 32 on 32bit */
-	unsigned long		last_active;	/* L: last active timestamp */
-	unsigned int		flags;		/* X: flags */
-	int			id;		/* I: worker id */
-
-	/* for rebinding worker to CPU */
-	struct work_struct	rebind_work;	/* L: for busy worker */
-};
+/* struct worker is defined in workqueue_internal.h */
 
 struct worker_pool {
-	struct global_cwq	*gcwq;		/* I: the owning gcwq */
+	spinlock_t		lock;		/* the pool lock */
+	unsigned int		cpu;		/* I: the associated cpu */
+	int			id;		/* I: pool ID */
 	unsigned int		flags;		/* X: flags */
 
 	struct list_head	worklist;	/* L: list of pending works */
@@ -165,34 +138,28 @@ struct worker_pool {
 	struct timer_list	idle_timer;	/* L: worker idle timeout */
 	struct timer_list	mayday_timer;	/* L: SOS timer for workers */
 
-	struct mutex		assoc_mutex;	/* protect GCWQ_DISASSOCIATED */
-	struct ida		worker_ida;	/* L: for worker IDs */
-};
-
-/*
- * Global per-cpu workqueue.  There's one and only one for each cpu
- * and all works are queued and processed here regardless of their
- * target workqueues.
- */
-struct global_cwq {
-	spinlock_t		lock;		/* the gcwq lock */
-	unsigned int		cpu;		/* I: the associated cpu */
-	unsigned int		flags;		/* L: GCWQ_* flags */
-
-	/* workers are chained either in busy_hash or pool idle_list */
-	struct hlist_head	busy_hash[BUSY_WORKER_HASH_SIZE];
+	/* workers are chained either in busy_hash or idle_list */
+	DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
 						/* L: hash of busy workers */
 
-	struct worker_pool	pools[NR_WORKER_POOLS];
-						/* normal and highpri pools */
+	struct mutex		assoc_mutex;	/* protect POOL_DISASSOCIATED */
+	struct ida		worker_ida;	/* L: for worker IDs */
+
+	/*
+	 * The current concurrency level.  As it's likely to be accessed
+	 * from other CPUs during try_to_wake_up(), put it in a separate
+	 * cacheline.
+	 */
+	atomic_t		nr_running ____cacheline_aligned_in_smp;
 } ____cacheline_aligned_in_smp;
 
 /*
- * The per-CPU workqueue.  The lower WORK_STRUCT_FLAG_BITS of
- * work_struct->data are used for flags and thus cwqs need to be
- * aligned at two's power of the number of flag bits.
+ * The per-pool workqueue.  While queued, the lower WORK_STRUCT_FLAG_BITS
+ * of work_struct->data are used for flags and the remaining high bits
+ * point to the pwq; thus, pwqs need to be aligned at two's power of the
+ * number of flag bits.
  */
-struct cpu_workqueue_struct {
+struct pool_workqueue {
 	struct worker_pool	*pool;		/* I: the associated pool */
 	struct workqueue_struct *wq;		/* I: the owning workqueue */
 	int			work_color;	/* L: current color */
@@ -241,16 +208,16 @@ typedef unsigned long mayday_mask_t;
 struct workqueue_struct {
 	unsigned int		flags;		/* W: WQ_* flags */
 	union {
-		struct cpu_workqueue_struct __percpu	*pcpu;
-		struct cpu_workqueue_struct		*single;
+		struct pool_workqueue __percpu		*pcpu;
+		struct pool_workqueue			*single;
 		unsigned long				v;
-	} cpu_wq;				/* I: cwq's */
+	} pool_wq;				/* I: pwq's */
 	struct list_head	list;		/* W: list of all workqueues */
 
 	struct mutex		flush_mutex;	/* protects wq flushing */
 	int			work_color;	/* F: current work color */
 	int			flush_color;	/* F: current flush color */
-	atomic_t		nr_cwqs_to_flush; /* flush in progress */
+	atomic_t		nr_pwqs_to_flush; /* flush in progress */
 	struct wq_flusher	*first_flusher;	/* F: first flusher */
 	struct list_head	flusher_queue;	/* F: flush waiters */
 	struct list_head	flusher_overflow; /* F: flush overflow list */
@@ -259,7 +226,7 @@ struct workqueue_struct {
 	struct worker		*rescuer;	/* I: rescue worker */
 
 	int			nr_drainers;	/* W: drain in progress */
-	int			saved_max_active; /* W: saved cwq max_active */
+	int			saved_max_active; /* W: saved pwq max_active */
 #ifdef CONFIG_LOCKDEP
 	struct lockdep_map	lockdep_map;
 #endif
@@ -280,16 +247,15 @@ EXPORT_SYMBOL_GPL(system_freezable_wq);
 #define CREATE_TRACE_POINTS
 #include <trace/events/workqueue.h>
 
-#define for_each_worker_pool(pool, gcwq)				\
-	for ((pool) = &(gcwq)->pools[0];				\
-	     (pool) < &(gcwq)->pools[NR_WORKER_POOLS]; (pool)++)
+#define for_each_std_worker_pool(pool, cpu)				\
+	for ((pool) = &std_worker_pools(cpu)[0];			\
+	     (pool) < &std_worker_pools(cpu)[NR_STD_WORKER_POOLS]; (pool)++)
 
-#define for_each_busy_worker(worker, i, pos, gcwq)			\
-	for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)			\
-		hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
+#define for_each_busy_worker(worker, i, pos, pool)			\
+	hash_for_each(pool->busy_hash, i, pos, worker, hentry)
 
-static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask,
-				  unsigned int sw)
+static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
+				unsigned int sw)
 {
 	if (cpu < nr_cpu_ids) {
 		if (sw & 1) {
@@ -300,42 +266,42 @@ static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask,
 		if (sw & 2)
 			return WORK_CPU_UNBOUND;
 	}
-	return WORK_CPU_NONE;
+	return WORK_CPU_END;
 }
 
-static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
-				struct workqueue_struct *wq)
+static inline int __next_pwq_cpu(int cpu, const struct cpumask *mask,
+				 struct workqueue_struct *wq)
 {
-	return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2);
+	return __next_wq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2);
 }
 
 /*
  * CPU iterators
  *
- * An extra gcwq is defined for an invalid cpu number
+ * An extra cpu number is defined using an invalid cpu number
  * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
- * specific CPU.  The following iterators are similar to
- * for_each_*_cpu() iterators but also considers the unbound gcwq.
+ * specific CPU.  The following iterators are similar to for_each_*_cpu()
+ * iterators but also considers the unbound CPU.
  *
- * for_each_gcwq_cpu()		: possible CPUs + WORK_CPU_UNBOUND
- * for_each_online_gcwq_cpu()	: online CPUs + WORK_CPU_UNBOUND
- * for_each_cwq_cpu()		: possible CPUs for bound workqueues,
+ * for_each_wq_cpu()		: possible CPUs + WORK_CPU_UNBOUND
+ * for_each_online_wq_cpu()	: online CPUs + WORK_CPU_UNBOUND
+ * for_each_pwq_cpu()		: possible CPUs for bound workqueues,
  *				  WORK_CPU_UNBOUND for unbound workqueues
  */
-#define for_each_gcwq_cpu(cpu)						\
-	for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3);		\
-	     (cpu) < WORK_CPU_NONE;					\
-	     (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
+#define for_each_wq_cpu(cpu)						\
+	for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, 3);		\
+	     (cpu) < WORK_CPU_END;					\
+	     (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, 3))
 
-#define for_each_online_gcwq_cpu(cpu)					\
-	for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3);		\
-	     (cpu) < WORK_CPU_NONE;					\
-	     (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
+#define for_each_online_wq_cpu(cpu)					\
+	for ((cpu) = __next_wq_cpu(-1, cpu_online_mask, 3);		\
+	     (cpu) < WORK_CPU_END;					\
+	     (cpu) = __next_wq_cpu((cpu), cpu_online_mask, 3))
 
-#define for_each_cwq_cpu(cpu, wq)					\
-	for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq));	\
-	     (cpu) < WORK_CPU_NONE;					\
-	     (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
+#define for_each_pwq_cpu(cpu, wq)					\
+	for ((cpu) = __next_pwq_cpu(-1, cpu_possible_mask, (wq));	\
+	     (cpu) < WORK_CPU_END;					\
+	     (cpu) = __next_pwq_cpu((cpu), cpu_possible_mask, (wq)))
 
 #ifdef CONFIG_DEBUG_OBJECTS_WORK
 
@@ -459,57 +425,69 @@ static LIST_HEAD(workqueues);
 static bool workqueue_freezing;		/* W: have wqs started freezing? */
 
 /*
- * The almighty global cpu workqueues.  nr_running is the only field
- * which is expected to be used frequently by other cpus via
- * try_to_wake_up().  Put it in a separate cacheline.
+ * The CPU and unbound standard worker pools.  The unbound ones have
+ * POOL_DISASSOCIATED set, and their workers have WORKER_UNBOUND set.
  */
-static DEFINE_PER_CPU(struct global_cwq, global_cwq);
-static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, pool_nr_running[NR_WORKER_POOLS]);
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS],
+				     cpu_std_worker_pools);
+static struct worker_pool unbound_std_worker_pools[NR_STD_WORKER_POOLS];
 
-/*
- * Global cpu workqueue and nr_running counter for unbound gcwq.  The
- * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
- * workers have WORKER_UNBOUND set.
- */
-static struct global_cwq unbound_global_cwq;
-static atomic_t unbound_pool_nr_running[NR_WORKER_POOLS] = {
-	[0 ... NR_WORKER_POOLS - 1]	= ATOMIC_INIT(0),	/* always 0 */
-};
+/* idr of all pools */
+static DEFINE_MUTEX(worker_pool_idr_mutex);
+static DEFINE_IDR(worker_pool_idr);
 
 static int worker_thread(void *__worker);
 
-static int worker_pool_pri(struct worker_pool *pool)
+static struct worker_pool *std_worker_pools(int cpu)
 {
-	return pool - pool->gcwq->pools;
+	if (cpu != WORK_CPU_UNBOUND)
+		return per_cpu(cpu_std_worker_pools, cpu);
+	else
+		return unbound_std_worker_pools;
 }
 
-static struct global_cwq *get_gcwq(unsigned int cpu)
+static int std_worker_pool_pri(struct worker_pool *pool)
 {
-	if (cpu != WORK_CPU_UNBOUND)
-		return &per_cpu(global_cwq, cpu);
-	else
-		return &unbound_global_cwq;
+	return pool - std_worker_pools(pool->cpu);
 }
 
-static atomic_t *get_pool_nr_running(struct worker_pool *pool)
+/* allocate ID and assign it to @pool */
+static int worker_pool_assign_id(struct worker_pool *pool)
 {
-	int cpu = pool->gcwq->cpu;
-	int idx = worker_pool_pri(pool);
+	int ret;
 
-	if (cpu != WORK_CPU_UNBOUND)
-		return &per_cpu(pool_nr_running, cpu)[idx];
-	else
-		return &unbound_pool_nr_running[idx];
+	mutex_lock(&worker_pool_idr_mutex);
+	idr_pre_get(&worker_pool_idr, GFP_KERNEL);
+	ret = idr_get_new(&worker_pool_idr, pool, &pool->id);
+	mutex_unlock(&worker_pool_idr_mutex);
+
+	return ret;
 }
 
-static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
-					    struct workqueue_struct *wq)
+/*
+ * Lookup worker_pool by id.  The idr currently is built during boot and
+ * never modified.  Don't worry about locking for now.
+ */
+static struct worker_pool *worker_pool_by_id(int pool_id)
+{
+	return idr_find(&worker_pool_idr, pool_id);
+}
+
+static struct worker_pool *get_std_worker_pool(int cpu, bool highpri)
+{
+	struct worker_pool *pools = std_worker_pools(cpu);
+
+	return &pools[highpri];
+}
+
+static struct pool_workqueue *get_pwq(unsigned int cpu,
+				      struct workqueue_struct *wq)
 {
 	if (!(wq->flags & WQ_UNBOUND)) {
 		if (likely(cpu < nr_cpu_ids))
-			return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
+			return per_cpu_ptr(wq->pool_wq.pcpu, cpu);
 	} else if (likely(cpu == WORK_CPU_UNBOUND))
-		return wq->cpu_wq.single;
+		return wq->pool_wq.single;
 	return NULL;
 }
 
@@ -530,19 +508,19 @@ static int work_next_color(int color)
 }
 
 /*
- * While queued, %WORK_STRUCT_CWQ is set and non flag bits of a work's data
- * contain the pointer to the queued cwq.  Once execution starts, the flag
- * is cleared and the high bits contain OFFQ flags and CPU number.
+ * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
+ * contain the pointer to the queued pwq.  Once execution starts, the flag
+ * is cleared and the high bits contain OFFQ flags and pool ID.
  *
- * set_work_cwq(), set_work_cpu_and_clear_pending(), mark_work_canceling()
- * and clear_work_data() can be used to set the cwq, cpu or clear
+ * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
+ * and clear_work_data() can be used to set the pwq, pool or clear
  * work->data.  These functions should only be called while the work is
  * owned - ie. while the PENDING bit is set.
  *
- * get_work_[g]cwq() can be used to obtain the gcwq or cwq corresponding to
- * a work.  gcwq is available once the work has been queued anywhere after
- * initialization until it is sync canceled.  cwq is available only while
- * the work item is queued.
+ * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
+ * corresponding to a work.  Pool is available once the work has been
+ * queued anywhere after initialization until it is sync canceled.  pwq is
+ * available only while the work item is queued.
  *
  * %WORK_OFFQ_CANCELING is used to mark a work item which is being
  * canceled.  While being canceled, a work item may have its PENDING set
@@ -556,16 +534,22 @@ static inline void set_work_data(struct work_struct *work, unsigned long data,
 	atomic_long_set(&work->data, data | flags | work_static(work));
 }
 
-static void set_work_cwq(struct work_struct *work,
-			 struct cpu_workqueue_struct *cwq,
+static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq,
 			 unsigned long extra_flags)
 {
-	set_work_data(work, (unsigned long)cwq,
-		      WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags);
+	set_work_data(work, (unsigned long)pwq,
+		      WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags);
 }
 
-static void set_work_cpu_and_clear_pending(struct work_struct *work,
-					   unsigned int cpu)
+static void set_work_pool_and_keep_pending(struct work_struct *work,
+					   int pool_id)
+{
+	set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT,
+		      WORK_STRUCT_PENDING);
+}
+
+static void set_work_pool_and_clear_pending(struct work_struct *work,
+					    int pool_id)
 {
 	/*
 	 * The following wmb is paired with the implied mb in
@@ -574,67 +558,92 @@ static void set_work_cpu_and_clear_pending(struct work_struct *work,
 	 * owner.
 	 */
 	smp_wmb();
-	set_work_data(work, (unsigned long)cpu << WORK_OFFQ_CPU_SHIFT, 0);
+	set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0);
 }
 
 static void clear_work_data(struct work_struct *work)
 {
-	smp_wmb();	/* see set_work_cpu_and_clear_pending() */
-	set_work_data(work, WORK_STRUCT_NO_CPU, 0);
+	smp_wmb();	/* see set_work_pool_and_clear_pending() */
+	set_work_data(work, WORK_STRUCT_NO_POOL, 0);
 }
 
-static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work)
+static struct pool_workqueue *get_work_pwq(struct work_struct *work)
 {
 	unsigned long data = atomic_long_read(&work->data);
 
-	if (data & WORK_STRUCT_CWQ)
+	if (data & WORK_STRUCT_PWQ)
 		return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
 	else
 		return NULL;
 }
 
-static struct global_cwq *get_work_gcwq(struct work_struct *work)
+/**
+ * get_work_pool - return the worker_pool a given work was associated with
+ * @work: the work item of interest
+ *
+ * Return the worker_pool @work was last associated with.  %NULL if none.
+ */
+static struct worker_pool *get_work_pool(struct work_struct *work)
 {
 	unsigned long data = atomic_long_read(&work->data);
-	unsigned int cpu;
+	struct worker_pool *pool;
+	int pool_id;
 
-	if (data & WORK_STRUCT_CWQ)
-		return ((struct cpu_workqueue_struct *)
-			(data & WORK_STRUCT_WQ_DATA_MASK))->pool->gcwq;
+	if (data & WORK_STRUCT_PWQ)
+		return ((struct pool_workqueue *)
+			(data & WORK_STRUCT_WQ_DATA_MASK))->pool;
 
-	cpu = data >> WORK_OFFQ_CPU_SHIFT;
-	if (cpu == WORK_CPU_NONE)
+	pool_id = data >> WORK_OFFQ_POOL_SHIFT;
+	if (pool_id == WORK_OFFQ_POOL_NONE)
 		return NULL;
 
-	BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND);
-	return get_gcwq(cpu);
+	pool = worker_pool_by_id(pool_id);
+	WARN_ON_ONCE(!pool);
+	return pool;
+}
+
+/**
+ * get_work_pool_id - return the worker pool ID a given work is associated with
+ * @work: the work item of interest
+ *
+ * Return the worker_pool ID @work was last associated with.
+ * %WORK_OFFQ_POOL_NONE if none.
+ */
+static int get_work_pool_id(struct work_struct *work)
+{
+	unsigned long data = atomic_long_read(&work->data);
+
+	if (data & WORK_STRUCT_PWQ)
+		return ((struct pool_workqueue *)
+			(data & WORK_STRUCT_WQ_DATA_MASK))->pool->id;
+
+	return data >> WORK_OFFQ_POOL_SHIFT;
 }
 
 static void mark_work_canceling(struct work_struct *work)
 {
-	struct global_cwq *gcwq = get_work_gcwq(work);
-	unsigned long cpu = gcwq ? gcwq->cpu : WORK_CPU_NONE;
+	unsigned long pool_id = get_work_pool_id(work);
 
-	set_work_data(work, (cpu << WORK_OFFQ_CPU_SHIFT) | WORK_OFFQ_CANCELING,
-		      WORK_STRUCT_PENDING);
+	pool_id <<= WORK_OFFQ_POOL_SHIFT;
+	set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING);
 }
 
 static bool work_is_canceling(struct work_struct *work)
 {
 	unsigned long data = atomic_long_read(&work->data);
 
-	return !(data & WORK_STRUCT_CWQ) && (data & WORK_OFFQ_CANCELING);
+	return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING);
 }
 
 /*
  * Policy functions.  These define the policies on how the global worker
  * pools are managed.  Unless noted otherwise, these functions assume that
- * they're being called with gcwq->lock held.
+ * they're being called with pool->lock held.
  */
 
 static bool __need_more_worker(struct worker_pool *pool)
 {
-	return !atomic_read(get_pool_nr_running(pool));
+	return !atomic_read(&pool->nr_running);
 }
 
 /*
@@ -642,7 +651,7 @@ static bool __need_more_worker(struct worker_pool *pool)
  * running workers.
  *
  * Note that, because unbound workers never contribute to nr_running, this
- * function will always return %true for unbound gcwq as long as the
+ * function will always return %true for unbound pools as long as the
  * worklist isn't empty.
  */
 static bool need_more_worker(struct worker_pool *pool)
@@ -659,9 +668,8 @@ static bool may_start_working(struct worker_pool *pool)
 /* Do I need to keep working?  Called from currently running workers. */
 static bool keep_working(struct worker_pool *pool)
 {
-	atomic_t *nr_running = get_pool_nr_running(pool);
-
-	return !list_empty(&pool->worklist) && atomic_read(nr_running) <= 1;
+	return !list_empty(&pool->worklist) &&
+		atomic_read(&pool->nr_running) <= 1;
 }
 
 /* Do we need a new worker?  Called from manager. */
@@ -714,7 +722,7 @@ static struct worker *first_worker(struct worker_pool *pool)
  * Wake up the first idle worker of @pool.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock).
+ * spin_lock_irq(pool->lock).
  */
 static void wake_up_worker(struct worker_pool *pool)
 {
@@ -740,8 +748,8 @@ void wq_worker_waking_up(struct task_struct *task, unsigned int cpu)
 	struct worker *worker = kthread_data(task);
 
 	if (!(worker->flags & WORKER_NOT_RUNNING)) {
-		WARN_ON_ONCE(worker->pool->gcwq->cpu != cpu);
-		atomic_inc(get_pool_nr_running(worker->pool));
+		WARN_ON_ONCE(worker->pool->cpu != cpu);
+		atomic_inc(&worker->pool->nr_running);
 	}
 }
 
@@ -764,12 +772,18 @@ struct task_struct *wq_worker_sleeping(struct task_struct *task,
 				       unsigned int cpu)
 {
 	struct worker *worker = kthread_data(task), *to_wakeup = NULL;
-	struct worker_pool *pool = worker->pool;
-	atomic_t *nr_running = get_pool_nr_running(pool);
+	struct worker_pool *pool;
 
+	/*
+	 * Rescuers, which may not have all the fields set up like normal
+	 * workers, also reach here, let's not access anything before
+	 * checking NOT_RUNNING.
+	 */
 	if (worker->flags & WORKER_NOT_RUNNING)
 		return NULL;
 
+	pool = worker->pool;
+
 	/* this can only happen on the local cpu */
 	BUG_ON(cpu != raw_smp_processor_id());
 
@@ -781,10 +795,11 @@ struct task_struct *wq_worker_sleeping(struct task_struct *task,
 	 * NOT_RUNNING is clear.  This means that we're bound to and
 	 * running on the local cpu w/ rq lock held and preemption
 	 * disabled, which in turn means that none else could be
-	 * manipulating idle_list, so dereferencing idle_list without gcwq
+	 * manipulating idle_list, so dereferencing idle_list without pool
 	 * lock is safe.
 	 */
-	if (atomic_dec_and_test(nr_running) && !list_empty(&pool->worklist))
+	if (atomic_dec_and_test(&pool->nr_running) &&
+	    !list_empty(&pool->worklist))
 		to_wakeup = first_worker(pool);
 	return to_wakeup ? to_wakeup->task : NULL;
 }
@@ -800,7 +815,7 @@ struct task_struct *wq_worker_sleeping(struct task_struct *task,
  * woken up.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock)
+ * spin_lock_irq(pool->lock)
  */
 static inline void worker_set_flags(struct worker *worker, unsigned int flags,
 				    bool wakeup)
@@ -816,14 +831,12 @@ static inline void worker_set_flags(struct worker *worker, unsigned int flags,
 	 */
 	if ((flags & WORKER_NOT_RUNNING) &&
 	    !(worker->flags & WORKER_NOT_RUNNING)) {
-		atomic_t *nr_running = get_pool_nr_running(pool);
-
 		if (wakeup) {
-			if (atomic_dec_and_test(nr_running) &&
+			if (atomic_dec_and_test(&pool->nr_running) &&
 			    !list_empty(&pool->worklist))
 				wake_up_worker(pool);
 		} else
-			atomic_dec(nr_running);
+			atomic_dec(&pool->nr_running);
 	}
 
 	worker->flags |= flags;
@@ -837,7 +850,7 @@ static inline void worker_set_flags(struct worker *worker, unsigned int flags,
  * Clear @flags in @worker->flags and adjust nr_running accordingly.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock)
+ * spin_lock_irq(pool->lock)
  */
 static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
 {
@@ -855,87 +868,56 @@ static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
 	 */
 	if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
 		if (!(worker->flags & WORKER_NOT_RUNNING))
-			atomic_inc(get_pool_nr_running(pool));
+			atomic_inc(&pool->nr_running);
 }
 
 /**
- * busy_worker_head - return the busy hash head for a work
- * @gcwq: gcwq of interest
- * @work: work to be hashed
- *
- * Return hash head of @gcwq for @work.
- *
- * CONTEXT:
- * spin_lock_irq(gcwq->lock).
- *
- * RETURNS:
- * Pointer to the hash head.
- */
-static struct hlist_head *busy_worker_head(struct global_cwq *gcwq,
-					   struct work_struct *work)
-{
-	const int base_shift = ilog2(sizeof(struct work_struct));
-	unsigned long v = (unsigned long)work;
-
-	/* simple shift and fold hash, do we need something better? */
-	v >>= base_shift;
-	v += v >> BUSY_WORKER_HASH_ORDER;
-	v &= BUSY_WORKER_HASH_MASK;
-
-	return &gcwq->busy_hash[v];
-}
-
-/**
- * __find_worker_executing_work - find worker which is executing a work
- * @gcwq: gcwq of interest
- * @bwh: hash head as returned by busy_worker_head()
+ * find_worker_executing_work - find worker which is executing a work
+ * @pool: pool of interest
  * @work: work to find worker for
  *
- * Find a worker which is executing @work on @gcwq.  @bwh should be
- * the hash head obtained by calling busy_worker_head() with the same
- * work.
+ * Find a worker which is executing @work on @pool by searching
+ * @pool->busy_hash which is keyed by the address of @work.  For a worker
+ * to match, its current execution should match the address of @work and
+ * its work function.  This is to avoid unwanted dependency between
+ * unrelated work executions through a work item being recycled while still
+ * being executed.
+ *
+ * This is a bit tricky.  A work item may be freed once its execution
+ * starts and nothing prevents the freed area from being recycled for
+ * another work item.  If the same work item address ends up being reused
+ * before the original execution finishes, workqueue will identify the
+ * recycled work item as currently executing and make it wait until the
+ * current execution finishes, introducing an unwanted dependency.
+ *
+ * This function checks the work item address, work function and workqueue
+ * to avoid false positives.  Note that this isn't complete as one may
+ * construct a work function which can introduce dependency onto itself
+ * through a recycled work item.  Well, if somebody wants to shoot oneself
+ * in the foot that badly, there's only so much we can do, and if such
+ * deadlock actually occurs, it should be easy to locate the culprit work
+ * function.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock).
+ * spin_lock_irq(pool->lock).
  *
  * RETURNS:
  * Pointer to worker which is executing @work if found, NULL
  * otherwise.
  */
-static struct worker *__find_worker_executing_work(struct global_cwq *gcwq,
-						   struct hlist_head *bwh,
-						   struct work_struct *work)
+static struct worker *find_worker_executing_work(struct worker_pool *pool,
+						 struct work_struct *work)
 {
 	struct worker *worker;
 	struct hlist_node *tmp;
 
-	hlist_for_each_entry(worker, tmp, bwh, hentry)
-		if (worker->current_work == work)
+	hash_for_each_possible(pool->busy_hash, worker, tmp, hentry,
+			       (unsigned long)work)
+		if (worker->current_work == work &&
+		    worker->current_func == work->func)
 			return worker;
-	return NULL;
-}
 
-/**
- * find_worker_executing_work - find worker which is executing a work
- * @gcwq: gcwq of interest
- * @work: work to find worker for
- *
- * Find a worker which is executing @work on @gcwq.  This function is
- * identical to __find_worker_executing_work() except that this
- * function calculates @bwh itself.
- *
- * CONTEXT:
- * spin_lock_irq(gcwq->lock).
- *
- * RETURNS:
- * Pointer to worker which is executing @work if found, NULL
- * otherwise.
- */
-static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
-						 struct work_struct *work)
-{
-	return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work),
-					    work);
+	return NULL;
 }
 
 /**
@@ -953,7 +935,7 @@ static struct worker *find_worker_executing_work(struct global_cwq *gcwq,
  * nested inside outer list_for_each_entry_safe().
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock).
+ * spin_lock_irq(pool->lock).
  */
 static void move_linked_works(struct work_struct *work, struct list_head *head,
 			      struct work_struct **nextp)
@@ -979,67 +961,67 @@ static void move_linked_works(struct work_struct *work, struct list_head *head,
 		*nextp = n;
 }
 
-static void cwq_activate_delayed_work(struct work_struct *work)
+static void pwq_activate_delayed_work(struct work_struct *work)
 {
-	struct cpu_workqueue_struct *cwq = get_work_cwq(work);
+	struct pool_workqueue *pwq = get_work_pwq(work);
 
 	trace_workqueue_activate_work(work);
-	move_linked_works(work, &cwq->pool->worklist, NULL);
+	move_linked_works(work, &pwq->pool->worklist, NULL);
 	__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
-	cwq->nr_active++;
+	pwq->nr_active++;
 }
 
-static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq)
+static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
 {
-	struct work_struct *work = list_first_entry(&cwq->delayed_works,
+	struct work_struct *work = list_first_entry(&pwq->delayed_works,
 						    struct work_struct, entry);
 
-	cwq_activate_delayed_work(work);
+	pwq_activate_delayed_work(work);
 }
 
 /**
- * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
- * @cwq: cwq of interest
+ * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
+ * @pwq: pwq of interest
  * @color: color of work which left the queue
  *
  * A work either has completed or is removed from pending queue,
- * decrement nr_in_flight of its cwq and handle workqueue flushing.
+ * decrement nr_in_flight of its pwq and handle workqueue flushing.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock).
+ * spin_lock_irq(pool->lock).
  */
-static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color)
+static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color)
 {
 	/* ignore uncolored works */
 	if (color == WORK_NO_COLOR)
 		return;
 
-	cwq->nr_in_flight[color]--;
+	pwq->nr_in_flight[color]--;
 
-	cwq->nr_active--;
-	if (!list_empty(&cwq->delayed_works)) {
+	pwq->nr_active--;
+	if (!list_empty(&pwq->delayed_works)) {
 		/* one down, submit a delayed one */
-		if (cwq->nr_active < cwq->max_active)
-			cwq_activate_first_delayed(cwq);
+		if (pwq->nr_active < pwq->max_active)
+			pwq_activate_first_delayed(pwq);
 	}
 
 	/* is flush in progress and are we at the flushing tip? */
-	if (likely(cwq->flush_color != color))
+	if (likely(pwq->flush_color != color))
 		return;
 
 	/* are there still in-flight works? */
-	if (cwq->nr_in_flight[color])
+	if (pwq->nr_in_flight[color])
 		return;
 
-	/* this cwq is done, clear flush_color */
-	cwq->flush_color = -1;
+	/* this pwq is done, clear flush_color */
+	pwq->flush_color = -1;
 
 	/*
-	 * If this was the last cwq, wake up the first flusher.  It
+	 * If this was the last pwq, wake up the first flusher.  It
 	 * will handle the rest.
 	 */
-	if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush))
-		complete(&cwq->wq->first_flusher->done);
+	if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush))
+		complete(&pwq->wq->first_flusher->done);
 }
 
 /**
@@ -1070,7 +1052,8 @@ static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color)
 static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
 			       unsigned long *flags)
 {
-	struct global_cwq *gcwq;
+	struct worker_pool *pool;
+	struct pool_workqueue *pwq;
 
 	local_irq_save(*flags);
 
@@ -1095,41 +1078,43 @@ static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
 	 * The queueing is in progress, or it is already queued. Try to
 	 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
 	 */
-	gcwq = get_work_gcwq(work);
-	if (!gcwq)
+	pool = get_work_pool(work);
+	if (!pool)
 		goto fail;
 
-	spin_lock(&gcwq->lock);
-	if (!list_empty(&work->entry)) {
+	spin_lock(&pool->lock);
+	/*
+	 * work->data is guaranteed to point to pwq only while the work
+	 * item is queued on pwq->wq, and both updating work->data to point
+	 * to pwq on queueing and to pool on dequeueing are done under
+	 * pwq->pool->lock.  This in turn guarantees that, if work->data
+	 * points to pwq which is associated with a locked pool, the work
+	 * item is currently queued on that pool.
+	 */
+	pwq = get_work_pwq(work);
+	if (pwq && pwq->pool == pool) {
+		debug_work_deactivate(work);
+
 		/*
-		 * This work is queued, but perhaps we locked the wrong gcwq.
-		 * In that case we must see the new value after rmb(), see
-		 * insert_work()->wmb().
+		 * A delayed work item cannot be grabbed directly because
+		 * it might have linked NO_COLOR work items which, if left
+		 * on the delayed_list, will confuse pwq->nr_active
+		 * management later on and cause stall.  Make sure the work
+		 * item is activated before grabbing.
 		 */
-		smp_rmb();
-		if (gcwq == get_work_gcwq(work)) {
-			debug_work_deactivate(work);
+		if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
+			pwq_activate_delayed_work(work);
 
-			/*
-			 * A delayed work item cannot be grabbed directly
-			 * because it might have linked NO_COLOR work items
-			 * which, if left on the delayed_list, will confuse
-			 * cwq->nr_active management later on and cause
-			 * stall.  Make sure the work item is activated
-			 * before grabbing.
-			 */
-			if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
-				cwq_activate_delayed_work(work);
+		list_del_init(&work->entry);
+		pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work));
 
-			list_del_init(&work->entry);
-			cwq_dec_nr_in_flight(get_work_cwq(work),
-				get_work_color(work));
+		/* work->data points to pwq iff queued, point to pool */
+		set_work_pool_and_keep_pending(work, pool->id);
 
-			spin_unlock(&gcwq->lock);
-			return 1;
-		}
+		spin_unlock(&pool->lock);
+		return 1;
 	}
-	spin_unlock(&gcwq->lock);
+	spin_unlock(&pool->lock);
 fail:
 	local_irq_restore(*flags);
 	if (work_is_canceling(work))
@@ -1139,33 +1124,25 @@ static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
 }
 
 /**
- * insert_work - insert a work into gcwq
- * @cwq: cwq @work belongs to
+ * insert_work - insert a work into a pool
+ * @pwq: pwq @work belongs to
  * @work: work to insert
  * @head: insertion point
  * @extra_flags: extra WORK_STRUCT_* flags to set
  *
- * Insert @work which belongs to @cwq into @gcwq after @head.
- * @extra_flags is or'd to work_struct flags.
+ * Insert @work which belongs to @pwq after @head.  @extra_flags is or'd to
+ * work_struct flags.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock).
+ * spin_lock_irq(pool->lock).
  */
-static void insert_work(struct cpu_workqueue_struct *cwq,
-			struct work_struct *work, struct list_head *head,
-			unsigned int extra_flags)
+static void insert_work(struct pool_workqueue *pwq, struct work_struct *work,
+			struct list_head *head, unsigned int extra_flags)
 {
-	struct worker_pool *pool = cwq->pool;
+	struct worker_pool *pool = pwq->pool;
 
 	/* we own @work, set data and link */
-	set_work_cwq(work, cwq, extra_flags);
-
-	/*
-	 * Ensure that we get the right work->data if we see the
-	 * result of list_add() below, see try_to_grab_pending().
-	 */
-	smp_wmb();
-
+	set_work_pwq(work, pwq, extra_flags);
 	list_add_tail(&work->entry, head);
 
 	/*
@@ -1181,41 +1158,24 @@ static void insert_work(struct cpu_workqueue_struct *cwq,
 
 /*
  * Test whether @work is being queued from another work executing on the
- * same workqueue.  This is rather expensive and should only be used from
- * cold paths.
+ * same workqueue.
  */
 static bool is_chained_work(struct workqueue_struct *wq)
 {
-	unsigned long flags;
-	unsigned int cpu;
-
-	for_each_gcwq_cpu(cpu) {
-		struct global_cwq *gcwq = get_gcwq(cpu);
-		struct worker *worker;
-		struct hlist_node *pos;
-		int i;
+	struct worker *worker;
 
-		spin_lock_irqsave(&gcwq->lock, flags);
-		for_each_busy_worker(worker, i, pos, gcwq) {
-			if (worker->task != current)
-				continue;
-			spin_unlock_irqrestore(&gcwq->lock, flags);
-			/*
-			 * I'm @worker, no locking necessary.  See if @work
-			 * is headed to the same workqueue.
-			 */
-			return worker->current_cwq->wq == wq;
-		}
-		spin_unlock_irqrestore(&gcwq->lock, flags);
-	}
-	return false;
+	worker = current_wq_worker();
+	/*
+	 * Return %true iff I'm a worker execuing a work item on @wq.  If
+	 * I'm @worker, it's safe to dereference it without locking.
+	 */
+	return worker && worker->current_pwq->wq == wq;
 }
 
 static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
 			 struct work_struct *work)
 {
-	struct global_cwq *gcwq;
-	struct cpu_workqueue_struct *cwq;
+	struct pool_workqueue *pwq;
 	struct list_head *worklist;
 	unsigned int work_flags;
 	unsigned int req_cpu = cpu;
@@ -1235,9 +1195,9 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
 	    WARN_ON_ONCE(!is_chained_work(wq)))
 		return;
 
-	/* determine gcwq to use */
+	/* determine the pwq to use */
 	if (!(wq->flags & WQ_UNBOUND)) {
-		struct global_cwq *last_gcwq;
+		struct worker_pool *last_pool;
 
 		if (cpu == WORK_CPU_UNBOUND)
 			cpu = raw_smp_processor_id();
@@ -1248,55 +1208,54 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
 		 * work needs to be queued on that cpu to guarantee
 		 * non-reentrancy.
 		 */
-		gcwq = get_gcwq(cpu);
-		last_gcwq = get_work_gcwq(work);
+		pwq = get_pwq(cpu, wq);
+		last_pool = get_work_pool(work);
 
-		if (last_gcwq && last_gcwq != gcwq) {
+		if (last_pool && last_pool != pwq->pool) {
 			struct worker *worker;
 
-			spin_lock(&last_gcwq->lock);
+			spin_lock(&last_pool->lock);
 
-			worker = find_worker_executing_work(last_gcwq, work);
+			worker = find_worker_executing_work(last_pool, work);
 
-			if (worker && worker->current_cwq->wq == wq)
-				gcwq = last_gcwq;
-			else {
+			if (worker && worker->current_pwq->wq == wq) {
+				pwq = get_pwq(last_pool->cpu, wq);
+			} else {
 				/* meh... not running there, queue here */
-				spin_unlock(&last_gcwq->lock);
-				spin_lock(&gcwq->lock);
+				spin_unlock(&last_pool->lock);
+				spin_lock(&pwq->pool->lock);
 			}
 		} else {
-			spin_lock(&gcwq->lock);
+			spin_lock(&pwq->pool->lock);
 		}
 	} else {
-		gcwq = get_gcwq(WORK_CPU_UNBOUND);
-		spin_lock(&gcwq->lock);
+		pwq = get_pwq(WORK_CPU_UNBOUND, wq);
+		spin_lock(&pwq->pool->lock);
 	}
 
-	/* gcwq determined, get cwq and queue */
-	cwq = get_cwq(gcwq->cpu, wq);
-	trace_workqueue_queue_work(req_cpu, cwq, work);
+	/* pwq determined, queue */
+	trace_workqueue_queue_work(req_cpu, pwq, work);
 
 	if (WARN_ON(!list_empty(&work->entry))) {
-		spin_unlock(&gcwq->lock);
+		spin_unlock(&pwq->pool->lock);
 		return;
 	}
 
-	cwq->nr_in_flight[cwq->work_color]++;
-	work_flags = work_color_to_flags(cwq->work_color);
+	pwq->nr_in_flight[pwq->work_color]++;
+	work_flags = work_color_to_flags(pwq->work_color);
 
-	if (likely(cwq->nr_active < cwq->max_active)) {
+	if (likely(pwq->nr_active < pwq->max_active)) {
 		trace_workqueue_activate_work(work);
-		cwq->nr_active++;
-		worklist = &cwq->pool->worklist;
+		pwq->nr_active++;
+		worklist = &pwq->pool->worklist;
 	} else {
 		work_flags |= WORK_STRUCT_DELAYED;
-		worklist = &cwq->delayed_works;
+		worklist = &pwq->delayed_works;
 	}
 
-	insert_work(cwq, work, worklist, work_flags);
+	insert_work(pwq, work, worklist, work_flags);
 
-	spin_unlock(&gcwq->lock);
+	spin_unlock(&pwq->pool->lock);
 }
 
 /**
@@ -1347,19 +1306,17 @@ EXPORT_SYMBOL_GPL(queue_work);
 void delayed_work_timer_fn(unsigned long __data)
 {
 	struct delayed_work *dwork = (struct delayed_work *)__data;
-	struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work);
 
 	/* should have been called from irqsafe timer with irq already off */
-	__queue_work(dwork->cpu, cwq->wq, &dwork->work);
+	__queue_work(dwork->cpu, dwork->wq, &dwork->work);
 }
-EXPORT_SYMBOL_GPL(delayed_work_timer_fn);
+EXPORT_SYMBOL(delayed_work_timer_fn);
 
 static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
 				struct delayed_work *dwork, unsigned long delay)
 {
 	struct timer_list *timer = &dwork->timer;
 	struct work_struct *work = &dwork->work;
-	unsigned int lcpu;
 
 	WARN_ON_ONCE(timer->function != delayed_work_timer_fn ||
 		     timer->data != (unsigned long)dwork);
@@ -1379,30 +1336,7 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
 
 	timer_stats_timer_set_start_info(&dwork->timer);
 
-	/*
-	 * This stores cwq for the moment, for the timer_fn.  Note that the
-	 * work's gcwq is preserved to allow reentrance detection for
-	 * delayed works.
-	 */
-	if (!(wq->flags & WQ_UNBOUND)) {
-		struct global_cwq *gcwq = get_work_gcwq(work);
-
-		/*
-		 * If we cannot get the last gcwq from @work directly,
-		 * select the last CPU such that it avoids unnecessarily
-		 * triggering non-reentrancy check in __queue_work().
-		 */
-		lcpu = cpu;
-		if (gcwq)
-			lcpu = gcwq->cpu;
-		if (lcpu == WORK_CPU_UNBOUND)
-			lcpu = raw_smp_processor_id();
-	} else {
-		lcpu = WORK_CPU_UNBOUND;
-	}
-
-	set_work_cwq(work, get_cwq(lcpu, wq), 0);
-
+	dwork->wq = wq;
 	dwork->cpu = cpu;
 	timer->expires = jiffies + delay;
 
@@ -1519,12 +1453,11 @@ EXPORT_SYMBOL_GPL(mod_delayed_work);
  * necessary.
  *
  * LOCKING:
- * spin_lock_irq(gcwq->lock).
+ * spin_lock_irq(pool->lock).
  */
 static void worker_enter_idle(struct worker *worker)
 {
 	struct worker_pool *pool = worker->pool;
-	struct global_cwq *gcwq = pool->gcwq;
 
 	BUG_ON(worker->flags & WORKER_IDLE);
 	BUG_ON(!list_empty(&worker->entry) &&
@@ -1542,14 +1475,14 @@ static void worker_enter_idle(struct worker *worker)
 		mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
 
 	/*
-	 * Sanity check nr_running.  Because gcwq_unbind_fn() releases
-	 * gcwq->lock between setting %WORKER_UNBOUND and zapping
+	 * Sanity check nr_running.  Because wq_unbind_fn() releases
+	 * pool->lock between setting %WORKER_UNBOUND and zapping
 	 * nr_running, the warning may trigger spuriously.  Check iff
 	 * unbind is not in progress.
 	 */
-	WARN_ON_ONCE(!(gcwq->flags & GCWQ_DISASSOCIATED) &&
+	WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
 		     pool->nr_workers == pool->nr_idle &&
-		     atomic_read(get_pool_nr_running(pool)));
+		     atomic_read(&pool->nr_running));
 }
 
 /**
@@ -1559,7 +1492,7 @@ static void worker_enter_idle(struct worker *worker)
  * @worker is leaving idle state.  Update stats.
  *
  * LOCKING:
- * spin_lock_irq(gcwq->lock).
+ * spin_lock_irq(pool->lock).
  */
 static void worker_leave_idle(struct worker *worker)
 {
@@ -1572,7 +1505,7 @@ static void worker_leave_idle(struct worker *worker)
 }
 
 /**
- * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
+ * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock pool
  * @worker: self
  *
  * Works which are scheduled while the cpu is online must at least be
@@ -1584,27 +1517,27 @@ static void worker_leave_idle(struct worker *worker)
  * themselves to the target cpu and may race with cpu going down or
  * coming online.  kthread_bind() can't be used because it may put the
  * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
- * verbatim as it's best effort and blocking and gcwq may be
+ * verbatim as it's best effort and blocking and pool may be
  * [dis]associated in the meantime.
  *
- * This function tries set_cpus_allowed() and locks gcwq and verifies the
- * binding against %GCWQ_DISASSOCIATED which is set during
+ * This function tries set_cpus_allowed() and locks pool and verifies the
+ * binding against %POOL_DISASSOCIATED which is set during
  * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker
  * enters idle state or fetches works without dropping lock, it can
  * guarantee the scheduling requirement described in the first paragraph.
  *
  * CONTEXT:
- * Might sleep.  Called without any lock but returns with gcwq->lock
+ * Might sleep.  Called without any lock but returns with pool->lock
  * held.
  *
  * RETURNS:
- * %true if the associated gcwq is online (@worker is successfully
+ * %true if the associated pool is online (@worker is successfully
  * bound), %false if offline.
  */
 static bool worker_maybe_bind_and_lock(struct worker *worker)
-__acquires(&gcwq->lock)
+__acquires(&pool->lock)
 {
-	struct global_cwq *gcwq = worker->pool->gcwq;
+	struct worker_pool *pool = worker->pool;
 	struct task_struct *task = worker->task;
 
 	while (true) {
@@ -1612,19 +1545,19 @@ __acquires(&gcwq->lock)
 		 * The following call may fail, succeed or succeed
 		 * without actually migrating the task to the cpu if
 		 * it races with cpu hotunplug operation.  Verify
-		 * against GCWQ_DISASSOCIATED.
+		 * against POOL_DISASSOCIATED.
 		 */
-		if (!(gcwq->flags & GCWQ_DISASSOCIATED))
-			set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu));
+		if (!(pool->flags & POOL_DISASSOCIATED))
+			set_cpus_allowed_ptr(task, get_cpu_mask(pool->cpu));
 
-		spin_lock_irq(&gcwq->lock);
-		if (gcwq->flags & GCWQ_DISASSOCIATED)
+		spin_lock_irq(&pool->lock);
+		if (pool->flags & POOL_DISASSOCIATED)
 			return false;
-		if (task_cpu(task) == gcwq->cpu &&
+		if (task_cpu(task) == pool->cpu &&
 		    cpumask_equal(&current->cpus_allowed,
-				  get_cpu_mask(gcwq->cpu)))
+				  get_cpu_mask(pool->cpu)))
 			return true;
-		spin_unlock_irq(&gcwq->lock);
+		spin_unlock_irq(&pool->lock);
 
 		/*
 		 * We've raced with CPU hot[un]plug.  Give it a breather
@@ -1643,15 +1576,13 @@ __acquires(&gcwq->lock)
  */
 static void idle_worker_rebind(struct worker *worker)
 {
-	struct global_cwq *gcwq = worker->pool->gcwq;
-
 	/* CPU may go down again inbetween, clear UNBOUND only on success */
 	if (worker_maybe_bind_and_lock(worker))
 		worker_clr_flags(worker, WORKER_UNBOUND);
 
 	/* rebind complete, become available again */
 	list_add(&worker->entry, &worker->pool->idle_list);
-	spin_unlock_irq(&gcwq->lock);
+	spin_unlock_irq(&worker->pool->lock);
 }
 
 /*
@@ -1663,19 +1594,18 @@ static void idle_worker_rebind(struct worker *worker)
 static void busy_worker_rebind_fn(struct work_struct *work)
 {
 	struct worker *worker = container_of(work, struct worker, rebind_work);
-	struct global_cwq *gcwq = worker->pool->gcwq;
 
 	if (worker_maybe_bind_and_lock(worker))
 		worker_clr_flags(worker, WORKER_UNBOUND);
 
-	spin_unlock_irq(&gcwq->lock);
+	spin_unlock_irq(&worker->pool->lock);
 }
 
 /**
- * rebind_workers - rebind all workers of a gcwq to the associated CPU
- * @gcwq: gcwq of interest
+ * rebind_workers - rebind all workers of a pool to the associated CPU
+ * @pool: pool of interest
  *
- * @gcwq->cpu is coming online.  Rebind all workers to the CPU.  Rebinding
+ * @pool->cpu is coming online.  Rebind all workers to the CPU.  Rebinding
  * is different for idle and busy ones.
  *
  * Idle ones will be removed from the idle_list and woken up.  They will
@@ -1693,38 +1623,32 @@ static void busy_worker_rebind_fn(struct work_struct *work)
  * including the manager will not appear on @idle_list until rebind is
  * complete, making local wake-ups safe.
  */
-static void rebind_workers(struct global_cwq *gcwq)
+static void rebind_workers(struct worker_pool *pool)
 {
-	struct worker_pool *pool;
 	struct worker *worker, *n;
 	struct hlist_node *pos;
 	int i;
 
-	lockdep_assert_held(&gcwq->lock);
-
-	for_each_worker_pool(pool, gcwq)
-		lockdep_assert_held(&pool->assoc_mutex);
+	lockdep_assert_held(&pool->assoc_mutex);
+	lockdep_assert_held(&pool->lock);
 
 	/* dequeue and kick idle ones */
-	for_each_worker_pool(pool, gcwq) {
-		list_for_each_entry_safe(worker, n, &pool->idle_list, entry) {
-			/*
-			 * idle workers should be off @pool->idle_list
-			 * until rebind is complete to avoid receiving
-			 * premature local wake-ups.
-			 */
-			list_del_init(&worker->entry);
+	list_for_each_entry_safe(worker, n, &pool->idle_list, entry) {
+		/*
+		 * idle workers should be off @pool->idle_list until rebind
+		 * is complete to avoid receiving premature local wake-ups.
+		 */
+		list_del_init(&worker->entry);
 
-			/*
-			 * worker_thread() will see the above dequeuing
-			 * and call idle_worker_rebind().
-			 */
-			wake_up_process(worker->task);
-		}
+		/*
+		 * worker_thread() will see the above dequeuing and call
+		 * idle_worker_rebind().
+		 */
+		wake_up_process(worker->task);
 	}
 
 	/* rebind busy workers */
-	for_each_busy_worker(worker, i, pos, gcwq) {
+	for_each_busy_worker(worker, i, pos, pool) {
 		struct work_struct *rebind_work = &worker->rebind_work;
 		struct workqueue_struct *wq;
 
@@ -1736,16 +1660,16 @@ static void rebind_workers(struct global_cwq *gcwq)
 
 		/*
 		 * wq doesn't really matter but let's keep @worker->pool
-		 * and @cwq->pool consistent for sanity.
+		 * and @pwq->pool consistent for sanity.
 		 */
-		if (worker_pool_pri(worker->pool))
+		if (std_worker_pool_pri(worker->pool))
 			wq = system_highpri_wq;
 		else
 			wq = system_wq;
 
-		insert_work(get_cwq(gcwq->cpu, wq), rebind_work,
-			worker->scheduled.next,
-			work_color_to_flags(WORK_NO_COLOR));
+		insert_work(get_pwq(pool->cpu, wq), rebind_work,
+			    worker->scheduled.next,
+			    work_color_to_flags(WORK_NO_COLOR));
 	}
 }
 
@@ -1780,19 +1704,18 @@ static struct worker *alloc_worker(void)
  */
 static struct worker *create_worker(struct worker_pool *pool)
 {
-	struct global_cwq *gcwq = pool->gcwq;
-	const char *pri = worker_pool_pri(pool) ? "H" : "";
+	const char *pri = std_worker_pool_pri(pool) ? "H" : "";
 	struct worker *worker = NULL;
 	int id = -1;
 
-	spin_lock_irq(&gcwq->lock);
+	spin_lock_irq(&pool->lock);
 	while (ida_get_new(&pool->worker_ida, &id)) {
-		spin_unlock_irq(&gcwq->lock);
+		spin_unlock_irq(&pool->lock);
 		if (!ida_pre_get(&pool->worker_ida, GFP_KERNEL))
 			goto fail;
-		spin_lock_irq(&gcwq->lock);
+		spin_lock_irq(&pool->lock);
 	}
-	spin_unlock_irq(&gcwq->lock);
+	spin_unlock_irq(&pool->lock);
 
 	worker = alloc_worker();
 	if (!worker)
@@ -1801,30 +1724,30 @@ static struct worker *create_worker(struct worker_pool *pool)
 	worker->pool = pool;
 	worker->id = id;
 
-	if (gcwq->cpu != WORK_CPU_UNBOUND)
+	if (pool->cpu != WORK_CPU_UNBOUND)
 		worker->task = kthread_create_on_node(worker_thread,
-					worker, cpu_to_node(gcwq->cpu),
-					"kworker/%u:%d%s", gcwq->cpu, id, pri);
+					worker, cpu_to_node(pool->cpu),
+					"kworker/%u:%d%s", pool->cpu, id, pri);
 	else
 		worker->task = kthread_create(worker_thread, worker,
 					      "kworker/u:%d%s", id, pri);
 	if (IS_ERR(worker->task))
 		goto fail;
 
-	if (worker_pool_pri(pool))
+	if (std_worker_pool_pri(pool))
 		set_user_nice(worker->task, HIGHPRI_NICE_LEVEL);
 
 	/*
 	 * Determine CPU binding of the new worker depending on
-	 * %GCWQ_DISASSOCIATED.  The caller is responsible for ensuring the
+	 * %POOL_DISASSOCIATED.  The caller is responsible for ensuring the
 	 * flag remains stable across this function.  See the comments
 	 * above the flag definition for details.
 	 *
 	 * As an unbound worker may later become a regular one if CPU comes
 	 * online, make sure every worker has %PF_THREAD_BOUND set.
 	 */
-	if (!(gcwq->flags & GCWQ_DISASSOCIATED)) {
-		kthread_bind(worker->task, gcwq->cpu);
+	if (!(pool->flags & POOL_DISASSOCIATED)) {
+		kthread_bind(worker->task, pool->cpu);
 	} else {
 		worker->task->flags |= PF_THREAD_BOUND;
 		worker->flags |= WORKER_UNBOUND;
@@ -1833,9 +1756,9 @@ static struct worker *create_worker(struct worker_pool *pool)
 	return worker;
 fail:
 	if (id >= 0) {
-		spin_lock_irq(&gcwq->lock);
+		spin_lock_irq(&pool->lock);
 		ida_remove(&pool->worker_ida, id);
-		spin_unlock_irq(&gcwq->lock);
+		spin_unlock_irq(&pool->lock);
 	}
 	kfree(worker);
 	return NULL;
@@ -1845,10 +1768,10 @@ static struct worker *create_worker(struct worker_pool *pool)
  * start_worker - start a newly created worker
  * @worker: worker to start
  *
- * Make the gcwq aware of @worker and start it.
+ * Make the pool aware of @worker and start it.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock).
+ * spin_lock_irq(pool->lock).
  */
 static void start_worker(struct worker *worker)
 {
@@ -1862,15 +1785,14 @@ static void start_worker(struct worker *worker)
  * destroy_worker - destroy a workqueue worker
  * @worker: worker to be destroyed
  *
- * Destroy @worker and adjust @gcwq stats accordingly.
+ * Destroy @worker and adjust @pool stats accordingly.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock) which is released and regrabbed.
+ * spin_lock_irq(pool->lock) which is released and regrabbed.
  */
 static void destroy_worker(struct worker *worker)
 {
 	struct worker_pool *pool = worker->pool;
-	struct global_cwq *gcwq = pool->gcwq;
 	int id = worker->id;
 
 	/* sanity check frenzy */
@@ -1885,21 +1807,20 @@ static void destroy_worker(struct worker *worker)
 	list_del_init(&worker->entry);
 	worker->flags |= WORKER_DIE;
 
-	spin_unlock_irq(&gcwq->lock);
+	spin_unlock_irq(&pool->lock);
 
 	kthread_stop(worker->task);
 	kfree(worker);
 
-	spin_lock_irq(&gcwq->lock);
+	spin_lock_irq(&pool->lock);
 	ida_remove(&pool->worker_ida, id);
 }
 
 static void idle_worker_timeout(unsigned long __pool)
 {
 	struct worker_pool *pool = (void *)__pool;
-	struct global_cwq *gcwq = pool->gcwq;
 
-	spin_lock_irq(&gcwq->lock);
+	spin_lock_irq(&pool->lock);
 
 	if (too_many_workers(pool)) {
 		struct worker *worker;
@@ -1918,20 +1839,20 @@ static void idle_worker_timeout(unsigned long __pool)
 		}
 	}
 
-	spin_unlock_irq(&gcwq->lock);
+	spin_unlock_irq(&pool->lock);
 }
 
 static bool send_mayday(struct work_struct *work)
 {
-	struct cpu_workqueue_struct *cwq = get_work_cwq(work);
-	struct workqueue_struct *wq = cwq->wq;
+	struct pool_workqueue *pwq = get_work_pwq(work);
+	struct workqueue_struct *wq = pwq->wq;
 	unsigned int cpu;
 
 	if (!(wq->flags & WQ_RESCUER))
 		return false;
 
 	/* mayday mayday mayday */
-	cpu = cwq->pool->gcwq->cpu;
+	cpu = pwq->pool->cpu;
 	/* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
 	if (cpu == WORK_CPU_UNBOUND)
 		cpu = 0;
@@ -1940,13 +1861,12 @@ static bool send_mayday(struct work_struct *work)
 	return true;
 }
 
-static void gcwq_mayday_timeout(unsigned long __pool)
+static void pool_mayday_timeout(unsigned long __pool)
 {
 	struct worker_pool *pool = (void *)__pool;
-	struct global_cwq *gcwq = pool->gcwq;
 	struct work_struct *work;
 
-	spin_lock_irq(&gcwq->lock);
+	spin_lock_irq(&pool->lock);
 
 	if (need_to_create_worker(pool)) {
 		/*
@@ -1959,7 +1879,7 @@ static void gcwq_mayday_timeout(unsigned long __pool)
 			send_mayday(work);
 	}
 
-	spin_unlock_irq(&gcwq->lock);
+	spin_unlock_irq(&pool->lock);
 
 	mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
 }
@@ -1978,24 +1898,22 @@ static void gcwq_mayday_timeout(unsigned long __pool)
  * may_start_working() true.
  *
  * LOCKING:
- * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * spin_lock_irq(pool->lock) which may be released and regrabbed
  * multiple times.  Does GFP_KERNEL allocations.  Called only from
  * manager.
  *
  * RETURNS:
- * false if no action was taken and gcwq->lock stayed locked, true
+ * false if no action was taken and pool->lock stayed locked, true
  * otherwise.
  */
 static bool maybe_create_worker(struct worker_pool *pool)
-__releases(&gcwq->lock)
-__acquires(&gcwq->lock)
+__releases(&pool->lock)
+__acquires(&pool->lock)
 {
-	struct global_cwq *gcwq = pool->gcwq;
-
 	if (!need_to_create_worker(pool))
 		return false;
 restart:
-	spin_unlock_irq(&gcwq->lock);
+	spin_unlock_irq(&pool->lock);
 
 	/* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
 	mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
@@ -2006,7 +1924,7 @@ __acquires(&gcwq->lock)
 		worker = create_worker(pool);
 		if (worker) {
 			del_timer_sync(&pool->mayday_timer);
-			spin_lock_irq(&gcwq->lock);
+			spin_lock_irq(&pool->lock);
 			start_worker(worker);
 			BUG_ON(need_to_create_worker(pool));
 			return true;
@@ -2023,7 +1941,7 @@ __acquires(&gcwq->lock)
 	}
 
 	del_timer_sync(&pool->mayday_timer);
-	spin_lock_irq(&gcwq->lock);
+	spin_lock_irq(&pool->lock);
 	if (need_to_create_worker(pool))
 		goto restart;
 	return true;
@@ -2037,11 +1955,11 @@ __acquires(&gcwq->lock)
  * IDLE_WORKER_TIMEOUT.
  *
  * LOCKING:
- * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * spin_lock_irq(pool->lock) which may be released and regrabbed
  * multiple times.  Called only from manager.
  *
  * RETURNS:
- * false if no action was taken and gcwq->lock stayed locked, true
+ * false if no action was taken and pool->lock stayed locked, true
  * otherwise.
  */
 static bool maybe_destroy_workers(struct worker_pool *pool)
@@ -2071,21 +1989,21 @@ static bool maybe_destroy_workers(struct worker_pool *pool)
  * manage_workers - manage worker pool
  * @worker: self
  *
- * Assume the manager role and manage gcwq worker pool @worker belongs
+ * Assume the manager role and manage the worker pool @worker belongs
  * to.  At any given time, there can be only zero or one manager per
- * gcwq.  The exclusion is handled automatically by this function.
+ * pool.  The exclusion is handled automatically by this function.
  *
  * The caller can safely start processing works on false return.  On
  * true return, it's guaranteed that need_to_create_worker() is false
  * and may_start_working() is true.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * spin_lock_irq(pool->lock) which may be released and regrabbed
  * multiple times.  Does GFP_KERNEL allocations.
  *
  * RETURNS:
- * false if no action was taken and gcwq->lock stayed locked, true if
- * some action was taken.
+ * spin_lock_irq(pool->lock) which may be released and regrabbed
+ * multiple times.  Does GFP_KERNEL allocations.
  */
 static bool manage_workers(struct worker *worker)
 {
@@ -2107,20 +2025,20 @@ static bool manage_workers(struct worker *worker)
 	 * manager against CPU hotplug.
 	 *
 	 * assoc_mutex would always be free unless CPU hotplug is in
-	 * progress.  trylock first without dropping @gcwq->lock.
+	 * progress.  trylock first without dropping @pool->lock.
 	 */
 	if (unlikely(!mutex_trylock(&pool->assoc_mutex))) {
-		spin_unlock_irq(&pool->gcwq->lock);
+		spin_unlock_irq(&pool->lock);
 		mutex_lock(&pool->assoc_mutex);
 		/*
 		 * CPU hotplug could have happened while we were waiting
 		 * for assoc_mutex.  Hotplug itself can't handle us
 		 * because manager isn't either on idle or busy list, and
-		 * @gcwq's state and ours could have deviated.
+		 * @pool's state and ours could have deviated.
 		 *
 		 * As hotplug is now excluded via assoc_mutex, we can
 		 * simply try to bind.  It will succeed or fail depending
-		 * on @gcwq's current state.  Try it and adjust
+		 * on @pool's current state.  Try it and adjust
 		 * %WORKER_UNBOUND accordingly.
 		 */
 		if (worker_maybe_bind_and_lock(worker))
@@ -2157,18 +2075,15 @@ static bool manage_workers(struct worker *worker)
  * call this function to process a work.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock) which is released and regrabbed.
+ * spin_lock_irq(pool->lock) which is released and regrabbed.
  */
 static void process_one_work(struct worker *worker, struct work_struct *work)
-__releases(&gcwq->lock)
-__acquires(&gcwq->lock)
+__releases(&pool->lock)
+__acquires(&pool->lock)
 {
-	struct cpu_workqueue_struct *cwq = get_work_cwq(work);
+	struct pool_workqueue *pwq = get_work_pwq(work);
 	struct worker_pool *pool = worker->pool;
-	struct global_cwq *gcwq = pool->gcwq;
-	struct hlist_head *bwh = busy_worker_head(gcwq, work);
-	bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE;
-	work_func_t f = work->func;
+	bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
 	int work_color;
 	struct worker *collision;
 #ifdef CONFIG_LOCKDEP
@@ -2186,11 +2101,11 @@ __acquires(&gcwq->lock)
 	/*
 	 * Ensure we're on the correct CPU.  DISASSOCIATED test is
 	 * necessary to avoid spurious warnings from rescuers servicing the
-	 * unbound or a disassociated gcwq.
+	 * unbound or a disassociated pool.
 	 */
 	WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) &&
-		     !(gcwq->flags & GCWQ_DISASSOCIATED) &&
-		     raw_smp_processor_id() != gcwq->cpu);
+		     !(pool->flags & POOL_DISASSOCIATED) &&
+		     raw_smp_processor_id() != pool->cpu);
 
 	/*
 	 * A single work shouldn't be executed concurrently by
@@ -2198,7 +2113,7 @@ __acquires(&gcwq->lock)
 	 * already processing the work.  If so, defer the work to the
 	 * currently executing one.
 	 */
-	collision = __find_worker_executing_work(gcwq, bwh, work);
+	collision = find_worker_executing_work(pool, work);
 	if (unlikely(collision)) {
 		move_linked_works(work, &collision->scheduled, NULL);
 		return;
@@ -2206,9 +2121,10 @@ __acquires(&gcwq->lock)
 
 	/* claim and dequeue */
 	debug_work_deactivate(work);
-	hlist_add_head(&worker->hentry, bwh);
+	hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
 	worker->current_work = work;
-	worker->current_cwq = cwq;
+	worker->current_func = work->func;
+	worker->current_pwq = pwq;
 	work_color = get_work_color(work);
 
 	list_del_init(&work->entry);
@@ -2221,53 +2137,55 @@ __acquires(&gcwq->lock)
 		worker_set_flags(worker, WORKER_CPU_INTENSIVE, true);
 
 	/*
-	 * Unbound gcwq isn't concurrency managed and work items should be
+	 * Unbound pool isn't concurrency managed and work items should be
 	 * executed ASAP.  Wake up another worker if necessary.
 	 */
 	if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool))
 		wake_up_worker(pool);
 
 	/*
-	 * Record the last CPU and clear PENDING which should be the last
-	 * update to @work.  Also, do this inside @gcwq->lock so that
+	 * Record the last pool and clear PENDING which should be the last
+	 * update to @work.  Also, do this inside @pool->lock so that
 	 * PENDING and queued state changes happen together while IRQ is
 	 * disabled.
 	 */
-	set_work_cpu_and_clear_pending(work, gcwq->cpu);
+	set_work_pool_and_clear_pending(work, pool->id);
 
-	spin_unlock_irq(&gcwq->lock);
+	spin_unlock_irq(&pool->lock);
 
-	lock_map_acquire_read(&cwq->wq->lockdep_map);
+	lock_map_acquire_read(&pwq->wq->lockdep_map);
 	lock_map_acquire(&lockdep_map);
 	trace_workqueue_execute_start(work);
-	f(work);
+	worker->current_func(work);
 	/*
 	 * While we must be careful to not use "work" after this, the trace
 	 * point will only record its address.
 	 */
 	trace_workqueue_execute_end(work);
 	lock_map_release(&lockdep_map);
-	lock_map_release(&cwq->wq->lockdep_map);
+	lock_map_release(&pwq->wq->lockdep_map);
 
 	if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
 		pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
 		       "     last function: %pf\n",
-		       current->comm, preempt_count(), task_pid_nr(current), f);
+		       current->comm, preempt_count(), task_pid_nr(current),
+		       worker->current_func);
 		debug_show_held_locks(current);
 		dump_stack();
 	}
 
-	spin_lock_irq(&gcwq->lock);
+	spin_lock_irq(&pool->lock);
 
 	/* clear cpu intensive status */
 	if (unlikely(cpu_intensive))
 		worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
 
 	/* we're done with it, release */
-	hlist_del_init(&worker->hentry);
+	hash_del(&worker->hentry);
 	worker->current_work = NULL;
-	worker->current_cwq = NULL;
-	cwq_dec_nr_in_flight(cwq, work_color);
+	worker->current_func = NULL;
+	worker->current_pwq = NULL;
+	pwq_dec_nr_in_flight(pwq, work_color);
 }
 
 /**
@@ -2279,7 +2197,7 @@ __acquires(&gcwq->lock)
  * fetches a work from the top and executes it.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock) which may be released and regrabbed
+ * spin_lock_irq(pool->lock) which may be released and regrabbed
  * multiple times.
  */
 static void process_scheduled_works(struct worker *worker)
@@ -2295,8 +2213,8 @@ static void process_scheduled_works(struct worker *worker)
  * worker_thread - the worker thread function
  * @__worker: self
  *
- * The gcwq worker thread function.  There's a single dynamic pool of
- * these per each cpu.  These workers process all works regardless of
+ * The worker thread function.  There are NR_CPU_WORKER_POOLS dynamic pools
+ * of these per each cpu.  These workers process all works regardless of
  * their specific target workqueue.  The only exception is works which
  * belong to workqueues with a rescuer which will be explained in
  * rescuer_thread().
@@ -2305,16 +2223,15 @@ static int worker_thread(void *__worker)
 {
 	struct worker *worker = __worker;
 	struct worker_pool *pool = worker->pool;
-	struct global_cwq *gcwq = pool->gcwq;
 
 	/* tell the scheduler that this is a workqueue worker */
 	worker->task->flags |= PF_WQ_WORKER;
 woke_up:
-	spin_lock_irq(&gcwq->lock);
+	spin_lock_irq(&pool->lock);
 
 	/* we are off idle list if destruction or rebind is requested */
 	if (unlikely(list_empty(&worker->entry))) {
-		spin_unlock_irq(&gcwq->lock);
+		spin_unlock_irq(&pool->lock);
 
 		/* if DIE is set, destruction is requested */
 		if (worker->flags & WORKER_DIE) {
@@ -2373,52 +2290,59 @@ static int worker_thread(void *__worker)
 		goto recheck;
 
 	/*
-	 * gcwq->lock is held and there's no work to process and no
-	 * need to manage, sleep.  Workers are woken up only while
-	 * holding gcwq->lock or from local cpu, so setting the
-	 * current state before releasing gcwq->lock is enough to
-	 * prevent losing any event.
+	 * pool->lock is held and there's no work to process and no need to
+	 * manage, sleep.  Workers are woken up only while holding
+	 * pool->lock or from local cpu, so setting the current state
+	 * before releasing pool->lock is enough to prevent losing any
+	 * event.
 	 */
 	worker_enter_idle(worker);
 	__set_current_state(TASK_INTERRUPTIBLE);
-	spin_unlock_irq(&gcwq->lock);
+	spin_unlock_irq(&pool->lock);
 	schedule();
 	goto woke_up;
 }
 
 /**
  * rescuer_thread - the rescuer thread function
- * @__wq: the associated workqueue
+ * @__rescuer: self
  *
  * Workqueue rescuer thread function.  There's one rescuer for each
  * workqueue which has WQ_RESCUER set.
  *
- * Regular work processing on a gcwq may block trying to create a new
+ * Regular work processing on a pool may block trying to create a new
  * worker which uses GFP_KERNEL allocation which has slight chance of
  * developing into deadlock if some works currently on the same queue
  * need to be processed to satisfy the GFP_KERNEL allocation.  This is
  * the problem rescuer solves.
  *
- * When such condition is possible, the gcwq summons rescuers of all
- * workqueues which have works queued on the gcwq and let them process
+ * When such condition is possible, the pool summons rescuers of all
+ * workqueues which have works queued on the pool and let them process
  * those works so that forward progress can be guaranteed.
  *
  * This should happen rarely.
  */
-static int rescuer_thread(void *__wq)
+static int rescuer_thread(void *__rescuer)
 {
-	struct workqueue_struct *wq = __wq;
-	struct worker *rescuer = wq->rescuer;
+	struct worker *rescuer = __rescuer;
+	struct workqueue_struct *wq = rescuer->rescue_wq;
 	struct list_head *scheduled = &rescuer->scheduled;
 	bool is_unbound = wq->flags & WQ_UNBOUND;
 	unsigned int cpu;
 
 	set_user_nice(current, RESCUER_NICE_LEVEL);
+
+	/*
+	 * Mark rescuer as worker too.  As WORKER_PREP is never cleared, it
+	 * doesn't participate in concurrency management.
+	 */
+	rescuer->task->flags |= PF_WQ_WORKER;
 repeat:
 	set_current_state(TASK_INTERRUPTIBLE);
 
 	if (kthread_should_stop()) {
 		__set_current_state(TASK_RUNNING);
+		rescuer->task->flags &= ~PF_WQ_WORKER;
 		return 0;
 	}
 
@@ -2428,9 +2352,8 @@ static int rescuer_thread(void *__wq)
 	 */
 	for_each_mayday_cpu(cpu, wq->mayday_mask) {
 		unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu;
-		struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq);
-		struct worker_pool *pool = cwq->pool;
-		struct global_cwq *gcwq = pool->gcwq;
+		struct pool_workqueue *pwq = get_pwq(tcpu, wq);
+		struct worker_pool *pool = pwq->pool;
 		struct work_struct *work, *n;
 
 		__set_current_state(TASK_RUNNING);
@@ -2446,22 +2369,24 @@ static int rescuer_thread(void *__wq)
 		 */
 		BUG_ON(!list_empty(&rescuer->scheduled));
 		list_for_each_entry_safe(work, n, &pool->worklist, entry)
-			if (get_work_cwq(work) == cwq)
+			if (get_work_pwq(work) == pwq)
 				move_linked_works(work, scheduled, &n);
 
 		process_scheduled_works(rescuer);
 
 		/*
-		 * Leave this gcwq.  If keep_working() is %true, notify a
+		 * Leave this pool.  If keep_working() is %true, notify a
 		 * regular worker; otherwise, we end up with 0 concurrency
 		 * and stalling the execution.
 		 */
 		if (keep_working(pool))
 			wake_up_worker(pool);
 
-		spin_unlock_irq(&gcwq->lock);
+		spin_unlock_irq(&pool->lock);
 	}
 
+	/* rescuers should never participate in concurrency management */
+	WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
 	schedule();
 	goto repeat;
 }
@@ -2479,7 +2404,7 @@ static void wq_barrier_func(struct work_struct *work)
 
 /**
  * insert_wq_barrier - insert a barrier work
- * @cwq: cwq to insert barrier into
+ * @pwq: pwq to insert barrier into
  * @barr: wq_barrier to insert
  * @target: target work to attach @barr to
  * @worker: worker currently executing @target, NULL if @target is not executing
@@ -2496,12 +2421,12 @@ static void wq_barrier_func(struct work_struct *work)
  * after a work with LINKED flag set.
  *
  * Note that when @worker is non-NULL, @target may be modified
- * underneath us, so we can't reliably determine cwq from @target.
+ * underneath us, so we can't reliably determine pwq from @target.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock).
+ * spin_lock_irq(pool->lock).
  */
-static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
+static void insert_wq_barrier(struct pool_workqueue *pwq,
 			      struct wq_barrier *barr,
 			      struct work_struct *target, struct worker *worker)
 {
@@ -2509,7 +2434,7 @@ static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
 	unsigned int linked = 0;
 
 	/*
-	 * debugobject calls are safe here even with gcwq->lock locked
+	 * debugobject calls are safe here even with pool->lock locked
 	 * as we know for sure that this will not trigger any of the
 	 * checks and call back into the fixup functions where we
 	 * might deadlock.
@@ -2534,23 +2459,23 @@ static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
 	}
 
 	debug_work_activate(&barr->work);
-	insert_work(cwq, &barr->work, head,
+	insert_work(pwq, &barr->work, head,
 		    work_color_to_flags(WORK_NO_COLOR) | linked);
 }
 
 /**
- * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing
+ * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
  * @wq: workqueue being flushed
  * @flush_color: new flush color, < 0 for no-op
  * @work_color: new work color, < 0 for no-op
  *
- * Prepare cwqs for workqueue flushing.
+ * Prepare pwqs for workqueue flushing.
  *
- * If @flush_color is non-negative, flush_color on all cwqs should be
- * -1.  If no cwq has in-flight commands at the specified color, all
- * cwq->flush_color's stay at -1 and %false is returned.  If any cwq
- * has in flight commands, its cwq->flush_color is set to
- * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
+ * If @flush_color is non-negative, flush_color on all pwqs should be
+ * -1.  If no pwq has in-flight commands at the specified color, all
+ * pwq->flush_color's stay at -1 and %false is returned.  If any pwq
+ * has in flight commands, its pwq->flush_color is set to
+ * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
  * wakeup logic is armed and %true is returned.
  *
  * The caller should have initialized @wq->first_flusher prior to
@@ -2558,7 +2483,7 @@ static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
  * @flush_color is negative, no flush color update is done and %false
  * is returned.
  *
- * If @work_color is non-negative, all cwqs should have the same
+ * If @work_color is non-negative, all pwqs should have the same
  * work_color which is previous to @work_color and all will be
  * advanced to @work_color.
  *
@@ -2569,42 +2494,42 @@ static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
  * %true if @flush_color >= 0 and there's something to flush.  %false
  * otherwise.
  */
-static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq,
+static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
 				      int flush_color, int work_color)
 {
 	bool wait = false;
 	unsigned int cpu;
 
 	if (flush_color >= 0) {
-		BUG_ON(atomic_read(&wq->nr_cwqs_to_flush));
-		atomic_set(&wq->nr_cwqs_to_flush, 1);
+		BUG_ON(atomic_read(&wq->nr_pwqs_to_flush));
+		atomic_set(&wq->nr_pwqs_to_flush, 1);
 	}
 
-	for_each_cwq_cpu(cpu, wq) {
-		struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
-		struct global_cwq *gcwq = cwq->pool->gcwq;
+	for_each_pwq_cpu(cpu, wq) {
+		struct pool_workqueue *pwq = get_pwq(cpu, wq);
+		struct worker_pool *pool = pwq->pool;
 
-		spin_lock_irq(&gcwq->lock);
+		spin_lock_irq(&pool->lock);
 
 		if (flush_color >= 0) {
-			BUG_ON(cwq->flush_color != -1);
+			BUG_ON(pwq->flush_color != -1);
 
-			if (cwq->nr_in_flight[flush_color]) {
-				cwq->flush_color = flush_color;
-				atomic_inc(&wq->nr_cwqs_to_flush);
+			if (pwq->nr_in_flight[flush_color]) {
+				pwq->flush_color = flush_color;
+				atomic_inc(&wq->nr_pwqs_to_flush);
 				wait = true;
 			}
 		}
 
 		if (work_color >= 0) {
-			BUG_ON(work_color != work_next_color(cwq->work_color));
-			cwq->work_color = work_color;
+			BUG_ON(work_color != work_next_color(pwq->work_color));
+			pwq->work_color = work_color;
 		}
 
-		spin_unlock_irq(&gcwq->lock);
+		spin_unlock_irq(&pool->lock);
 	}
 
-	if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush))
+	if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
 		complete(&wq->first_flusher->done);
 
 	return wait;
@@ -2655,7 +2580,7 @@ void flush_workqueue(struct workqueue_struct *wq)
 
 			wq->first_flusher = &this_flusher;
 
-			if (!flush_workqueue_prep_cwqs(wq, wq->flush_color,
+			if (!flush_workqueue_prep_pwqs(wq, wq->flush_color,
 						       wq->work_color)) {
 				/* nothing to flush, done */
 				wq->flush_color = next_color;
@@ -2666,7 +2591,7 @@ void flush_workqueue(struct workqueue_struct *wq)
 			/* wait in queue */
 			BUG_ON(wq->flush_color == this_flusher.flush_color);
 			list_add_tail(&this_flusher.list, &wq->flusher_queue);
-			flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
+			flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
 		}
 	} else {
 		/*
@@ -2733,7 +2658,7 @@ void flush_workqueue(struct workqueue_struct *wq)
 
 			list_splice_tail_init(&wq->flusher_overflow,
 					      &wq->flusher_queue);
-			flush_workqueue_prep_cwqs(wq, -1, wq->work_color);
+			flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
 		}
 
 		if (list_empty(&wq->flusher_queue)) {
@@ -2743,7 +2668,7 @@ void flush_workqueue(struct workqueue_struct *wq)
 
 		/*
 		 * Need to flush more colors.  Make the next flusher
-		 * the new first flusher and arm cwqs.
+		 * the new first flusher and arm pwqs.
 		 */
 		BUG_ON(wq->flush_color == wq->work_color);
 		BUG_ON(wq->flush_color != next->flush_color);
@@ -2751,7 +2676,7 @@ void flush_workqueue(struct workqueue_struct *wq)
 		list_del_init(&next->list);
 		wq->first_flusher = next;
 
-		if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1))
+		if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1))
 			break;
 
 		/*
@@ -2794,13 +2719,13 @@ void drain_workqueue(struct workqueue_struct *wq)
 reflush:
 	flush_workqueue(wq);
 
-	for_each_cwq_cpu(cpu, wq) {
-		struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+	for_each_pwq_cpu(cpu, wq) {
+		struct pool_workqueue *pwq = get_pwq(cpu, wq);
 		bool drained;
 
-		spin_lock_irq(&cwq->pool->gcwq->lock);
-		drained = !cwq->nr_active && list_empty(&cwq->delayed_works);
-		spin_unlock_irq(&cwq->pool->gcwq->lock);
+		spin_lock_irq(&pwq->pool->lock);
+		drained = !pwq->nr_active && list_empty(&pwq->delayed_works);
+		spin_unlock_irq(&pwq->pool->lock);
 
 		if (drained)
 			continue;
@@ -2822,34 +2747,29 @@ EXPORT_SYMBOL_GPL(drain_workqueue);
 static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr)
 {
 	struct worker *worker = NULL;
-	struct global_cwq *gcwq;
-	struct cpu_workqueue_struct *cwq;
+	struct worker_pool *pool;
+	struct pool_workqueue *pwq;
 
 	might_sleep();
-	gcwq = get_work_gcwq(work);
-	if (!gcwq)
+	pool = get_work_pool(work);
+	if (!pool)
 		return false;
 
-	spin_lock_irq(&gcwq->lock);
-	if (!list_empty(&work->entry)) {
-		/*
-		 * See the comment near try_to_grab_pending()->smp_rmb().
-		 * If it was re-queued to a different gcwq under us, we
-		 * are not going to wait.
-		 */
-		smp_rmb();
-		cwq = get_work_cwq(work);
-		if (unlikely(!cwq || gcwq != cwq->pool->gcwq))
+	spin_lock_irq(&pool->lock);
+	/* see the comment in try_to_grab_pending() with the same code */
+	pwq = get_work_pwq(work);
+	if (pwq) {
+		if (unlikely(pwq->pool != pool))
 			goto already_gone;
 	} else {
-		worker = find_worker_executing_work(gcwq, work);
+		worker = find_worker_executing_work(pool, work);
 		if (!worker)
 			goto already_gone;
-		cwq = worker->current_cwq;
+		pwq = worker->current_pwq;
 	}
 
-	insert_wq_barrier(cwq, barr, work, worker);
-	spin_unlock_irq(&gcwq->lock);
+	insert_wq_barrier(pwq, barr, work, worker);
+	spin_unlock_irq(&pool->lock);
 
 	/*
 	 * If @max_active is 1 or rescuer is in use, flushing another work
@@ -2857,15 +2777,15 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr)
 	 * flusher is not running on the same workqueue by verifying write
 	 * access.
 	 */
-	if (cwq->wq->saved_max_active == 1 || cwq->wq->flags & WQ_RESCUER)
-		lock_map_acquire(&cwq->wq->lockdep_map);
+	if (pwq->wq->saved_max_active == 1 || pwq->wq->flags & WQ_RESCUER)
+		lock_map_acquire(&pwq->wq->lockdep_map);
 	else
-		lock_map_acquire_read(&cwq->wq->lockdep_map);
-	lock_map_release(&cwq->wq->lockdep_map);
+		lock_map_acquire_read(&pwq->wq->lockdep_map);
+	lock_map_release(&pwq->wq->lockdep_map);
 
 	return true;
 already_gone:
-	spin_unlock_irq(&gcwq->lock);
+	spin_unlock_irq(&pool->lock);
 	return false;
 }
 
@@ -2961,8 +2881,7 @@ bool flush_delayed_work(struct delayed_work *dwork)
 {
 	local_irq_disable();
 	if (del_timer_sync(&dwork->timer))
-		__queue_work(dwork->cpu,
-			     get_work_cwq(&dwork->work)->wq, &dwork->work);
+		__queue_work(dwork->cpu, dwork->wq, &dwork->work);
 	local_irq_enable();
 	return flush_work(&dwork->work);
 }
@@ -2992,7 +2911,8 @@ bool cancel_delayed_work(struct delayed_work *dwork)
 	if (unlikely(ret < 0))
 		return false;
 
-	set_work_cpu_and_clear_pending(&dwork->work, work_cpu(&dwork->work));
+	set_work_pool_and_clear_pending(&dwork->work,
+					get_work_pool_id(&dwork->work));
 	local_irq_restore(flags);
 	return ret;
 }
@@ -3171,46 +3091,46 @@ int keventd_up(void)
 	return system_wq != NULL;
 }
 
-static int alloc_cwqs(struct workqueue_struct *wq)
+static int alloc_pwqs(struct workqueue_struct *wq)
 {
 	/*
-	 * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
+	 * pwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
 	 * Make sure that the alignment isn't lower than that of
 	 * unsigned long long.
 	 */
-	const size_t size = sizeof(struct cpu_workqueue_struct);
+	const size_t size = sizeof(struct pool_workqueue);
 	const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
 				   __alignof__(unsigned long long));
 
 	if (!(wq->flags & WQ_UNBOUND))
-		wq->cpu_wq.pcpu = __alloc_percpu(size, align);
+		wq->pool_wq.pcpu = __alloc_percpu(size, align);
 	else {
 		void *ptr;
 
 		/*
-		 * Allocate enough room to align cwq and put an extra
+		 * Allocate enough room to align pwq and put an extra
 		 * pointer at the end pointing back to the originally
 		 * allocated pointer which will be used for free.
 		 */
 		ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL);
 		if (ptr) {
-			wq->cpu_wq.single = PTR_ALIGN(ptr, align);
-			*(void **)(wq->cpu_wq.single + 1) = ptr;
+			wq->pool_wq.single = PTR_ALIGN(ptr, align);
+			*(void **)(wq->pool_wq.single + 1) = ptr;
 		}
 	}
 
 	/* just in case, make sure it's actually aligned */
-	BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align));
-	return wq->cpu_wq.v ? 0 : -ENOMEM;
+	BUG_ON(!IS_ALIGNED(wq->pool_wq.v, align));
+	return wq->pool_wq.v ? 0 : -ENOMEM;
 }
 
-static void free_cwqs(struct workqueue_struct *wq)
+static void free_pwqs(struct workqueue_struct *wq)
 {
 	if (!(wq->flags & WQ_UNBOUND))
-		free_percpu(wq->cpu_wq.pcpu);
-	else if (wq->cpu_wq.single) {
-		/* the pointer to free is stored right after the cwq */
-		kfree(*(void **)(wq->cpu_wq.single + 1));
+		free_percpu(wq->pool_wq.pcpu);
+	else if (wq->pool_wq.single) {
+		/* the pointer to free is stored right after the pwq */
+		kfree(*(void **)(wq->pool_wq.single + 1));
 	}
 }
 
@@ -3264,27 +3184,25 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
 	wq->flags = flags;
 	wq->saved_max_active = max_active;
 	mutex_init(&wq->flush_mutex);
-	atomic_set(&wq->nr_cwqs_to_flush, 0);
+	atomic_set(&wq->nr_pwqs_to_flush, 0);
 	INIT_LIST_HEAD(&wq->flusher_queue);
 	INIT_LIST_HEAD(&wq->flusher_overflow);
 
 	lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
 	INIT_LIST_HEAD(&wq->list);
 
-	if (alloc_cwqs(wq) < 0)
+	if (alloc_pwqs(wq) < 0)
 		goto err;
 
-	for_each_cwq_cpu(cpu, wq) {
-		struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
-		struct global_cwq *gcwq = get_gcwq(cpu);
-		int pool_idx = (bool)(flags & WQ_HIGHPRI);
-
-		BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK);
-		cwq->pool = &gcwq->pools[pool_idx];
-		cwq->wq = wq;
-		cwq->flush_color = -1;
-		cwq->max_active = max_active;
-		INIT_LIST_HEAD(&cwq->delayed_works);
+	for_each_pwq_cpu(cpu, wq) {
+		struct pool_workqueue *pwq = get_pwq(cpu, wq);
+
+		BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
+		pwq->pool = get_std_worker_pool(cpu, flags & WQ_HIGHPRI);
+		pwq->wq = wq;
+		pwq->flush_color = -1;
+		pwq->max_active = max_active;
+		INIT_LIST_HEAD(&pwq->delayed_works);
 	}
 
 	if (flags & WQ_RESCUER) {
@@ -3297,7 +3215,8 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
 		if (!rescuer)
 			goto err;
 
-		rescuer->task = kthread_create(rescuer_thread, wq, "%s",
+		rescuer->rescue_wq = wq;
+		rescuer->task = kthread_create(rescuer_thread, rescuer, "%s",
 					       wq->name);
 		if (IS_ERR(rescuer->task))
 			goto err;
@@ -3314,8 +3233,8 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
 	spin_lock(&workqueue_lock);
 
 	if (workqueue_freezing && wq->flags & WQ_FREEZABLE)
-		for_each_cwq_cpu(cpu, wq)
-			get_cwq(cpu, wq)->max_active = 0;
+		for_each_pwq_cpu(cpu, wq)
+			get_pwq(cpu, wq)->max_active = 0;
 
 	list_add(&wq->list, &workqueues);
 
@@ -3324,7 +3243,7 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt,
 	return wq;
 err:
 	if (wq) {
-		free_cwqs(wq);
+		free_pwqs(wq);
 		free_mayday_mask(wq->mayday_mask);
 		kfree(wq->rescuer);
 		kfree(wq);
@@ -3355,14 +3274,14 @@ void destroy_workqueue(struct workqueue_struct *wq)
 	spin_unlock(&workqueue_lock);
 
 	/* sanity check */
-	for_each_cwq_cpu(cpu, wq) {
-		struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+	for_each_pwq_cpu(cpu, wq) {
+		struct pool_workqueue *pwq = get_pwq(cpu, wq);
 		int i;
 
 		for (i = 0; i < WORK_NR_COLORS; i++)
-			BUG_ON(cwq->nr_in_flight[i]);
-		BUG_ON(cwq->nr_active);
-		BUG_ON(!list_empty(&cwq->delayed_works));
+			BUG_ON(pwq->nr_in_flight[i]);
+		BUG_ON(pwq->nr_active);
+		BUG_ON(!list_empty(&pwq->delayed_works));
 	}
 
 	if (wq->flags & WQ_RESCUER) {
@@ -3371,29 +3290,29 @@ void destroy_workqueue(struct workqueue_struct *wq)
 		kfree(wq->rescuer);
 	}
 
-	free_cwqs(wq);
+	free_pwqs(wq);
 	kfree(wq);
 }
 EXPORT_SYMBOL_GPL(destroy_workqueue);
 
 /**
- * cwq_set_max_active - adjust max_active of a cwq
- * @cwq: target cpu_workqueue_struct
+ * pwq_set_max_active - adjust max_active of a pwq
+ * @pwq: target pool_workqueue
  * @max_active: new max_active value.
  *
- * Set @cwq->max_active to @max_active and activate delayed works if
+ * Set @pwq->max_active to @max_active and activate delayed works if
  * increased.
  *
  * CONTEXT:
- * spin_lock_irq(gcwq->lock).
+ * spin_lock_irq(pool->lock).
  */
-static void cwq_set_max_active(struct cpu_workqueue_struct *cwq, int max_active)
+static void pwq_set_max_active(struct pool_workqueue *pwq, int max_active)
 {
-	cwq->max_active = max_active;
+	pwq->max_active = max_active;
 
-	while (!list_empty(&cwq->delayed_works) &&
-	       cwq->nr_active < cwq->max_active)
-		cwq_activate_first_delayed(cwq);
+	while (!list_empty(&pwq->delayed_works) &&
+	       pwq->nr_active < pwq->max_active)
+		pwq_activate_first_delayed(pwq);
 }
 
 /**
@@ -3416,16 +3335,17 @@ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
 
 	wq->saved_max_active = max_active;
 
-	for_each_cwq_cpu(cpu, wq) {
-		struct global_cwq *gcwq = get_gcwq(cpu);
+	for_each_pwq_cpu(cpu, wq) {
+		struct pool_workqueue *pwq = get_pwq(cpu, wq);
+		struct worker_pool *pool = pwq->pool;
 
-		spin_lock_irq(&gcwq->lock);
+		spin_lock_irq(&pool->lock);
 
 		if (!(wq->flags & WQ_FREEZABLE) ||
-		    !(gcwq->flags & GCWQ_FREEZING))
-			cwq_set_max_active(get_cwq(gcwq->cpu, wq), max_active);
+		    !(pool->flags & POOL_FREEZING))
+			pwq_set_max_active(pwq, max_active);
 
-		spin_unlock_irq(&gcwq->lock);
+		spin_unlock_irq(&pool->lock);
 	}
 
 	spin_unlock(&workqueue_lock);
@@ -3446,27 +3366,12 @@ EXPORT_SYMBOL_GPL(workqueue_set_max_active);
  */
 bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq)
 {
-	struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+	struct pool_workqueue *pwq = get_pwq(cpu, wq);
 
-	return !list_empty(&cwq->delayed_works);
+	return !list_empty(&pwq->delayed_works);
 }
 EXPORT_SYMBOL_GPL(workqueue_congested);
 
-/**
- * work_cpu - return the last known associated cpu for @work
- * @work: the work of interest
- *
- * RETURNS:
- * CPU number if @work was ever queued.  WORK_CPU_NONE otherwise.
- */
-unsigned int work_cpu(struct work_struct *work)
-{
-	struct global_cwq *gcwq = get_work_gcwq(work);
-
-	return gcwq ? gcwq->cpu : WORK_CPU_NONE;
-}
-EXPORT_SYMBOL_GPL(work_cpu);
-
 /**
  * work_busy - test whether a work is currently pending or running
  * @work: the work to be tested
@@ -3474,29 +3379,25 @@ EXPORT_SYMBOL_GPL(work_cpu);
  * Test whether @work is currently pending or running.  There is no
  * synchronization around this function and the test result is
  * unreliable and only useful as advisory hints or for debugging.
- * Especially for reentrant wqs, the pending state might hide the
- * running state.
  *
  * RETURNS:
  * OR'd bitmask of WORK_BUSY_* bits.
  */
 unsigned int work_busy(struct work_struct *work)
 {
-	struct global_cwq *gcwq = get_work_gcwq(work);
+	struct worker_pool *pool = get_work_pool(work);
 	unsigned long flags;
 	unsigned int ret = 0;
 
-	if (!gcwq)
-		return 0;
-
-	spin_lock_irqsave(&gcwq->lock, flags);
-
 	if (work_pending(work))
 		ret |= WORK_BUSY_PENDING;
-	if (find_worker_executing_work(gcwq, work))
-		ret |= WORK_BUSY_RUNNING;
 
-	spin_unlock_irqrestore(&gcwq->lock, flags);
+	if (pool) {
+		spin_lock_irqsave(&pool->lock, flags);
+		if (find_worker_executing_work(pool, work))
+			ret |= WORK_BUSY_RUNNING;
+		spin_unlock_irqrestore(&pool->lock, flags);
+	}
 
 	return ret;
 }
@@ -3506,65 +3407,49 @@ EXPORT_SYMBOL_GPL(work_busy);
  * CPU hotplug.
  *
  * There are two challenges in supporting CPU hotplug.  Firstly, there
- * are a lot of assumptions on strong associations among work, cwq and
- * gcwq which make migrating pending and scheduled works very
+ * are a lot of assumptions on strong associations among work, pwq and
+ * pool which make migrating pending and scheduled works very
  * difficult to implement without impacting hot paths.  Secondly,
- * gcwqs serve mix of short, long and very long running works making
+ * worker pools serve mix of short, long and very long running works making
  * blocked draining impractical.
  *
- * This is solved by allowing a gcwq to be disassociated from the CPU
+ * This is solved by allowing the pools to be disassociated from the CPU
  * running as an unbound one and allowing it to be reattached later if the
  * cpu comes back online.
  */
 
-/* claim manager positions of all pools */
-static void gcwq_claim_assoc_and_lock(struct global_cwq *gcwq)
+static void wq_unbind_fn(struct work_struct *work)
 {
-	struct worker_pool *pool;
-
-	for_each_worker_pool(pool, gcwq)
-		mutex_lock_nested(&pool->assoc_mutex, pool - gcwq->pools);
-	spin_lock_irq(&gcwq->lock);
-}
-
-/* release manager positions */
-static void gcwq_release_assoc_and_unlock(struct global_cwq *gcwq)
-{
-	struct worker_pool *pool;
-
-	spin_unlock_irq(&gcwq->lock);
-	for_each_worker_pool(pool, gcwq)
-		mutex_unlock(&pool->assoc_mutex);
-}
-
-static void gcwq_unbind_fn(struct work_struct *work)
-{
-	struct global_cwq *gcwq = get_gcwq(smp_processor_id());
+	int cpu = smp_processor_id();
 	struct worker_pool *pool;
 	struct worker *worker;
 	struct hlist_node *pos;
 	int i;
 
-	BUG_ON(gcwq->cpu != smp_processor_id());
+	for_each_std_worker_pool(pool, cpu) {
+		BUG_ON(cpu != smp_processor_id());
 
-	gcwq_claim_assoc_and_lock(gcwq);
+		mutex_lock(&pool->assoc_mutex);
+		spin_lock_irq(&pool->lock);
 
-	/*
-	 * We've claimed all manager positions.  Make all workers unbound
-	 * and set DISASSOCIATED.  Before this, all workers except for the
-	 * ones which are still executing works from before the last CPU
-	 * down must be on the cpu.  After this, they may become diasporas.
-	 */
-	for_each_worker_pool(pool, gcwq)
+		/*
+		 * We've claimed all manager positions.  Make all workers
+		 * unbound and set DISASSOCIATED.  Before this, all workers
+		 * except for the ones which are still executing works from
+		 * before the last CPU down must be on the cpu.  After
+		 * this, they may become diasporas.
+		 */
 		list_for_each_entry(worker, &pool->idle_list, entry)
 			worker->flags |= WORKER_UNBOUND;
 
-	for_each_busy_worker(worker, i, pos, gcwq)
-		worker->flags |= WORKER_UNBOUND;
+		for_each_busy_worker(worker, i, pos, pool)
+			worker->flags |= WORKER_UNBOUND;
 
-	gcwq->flags |= GCWQ_DISASSOCIATED;
+		pool->flags |= POOL_DISASSOCIATED;
 
-	gcwq_release_assoc_and_unlock(gcwq);
+		spin_unlock_irq(&pool->lock);
+		mutex_unlock(&pool->assoc_mutex);
+	}
 
 	/*
 	 * Call schedule() so that we cross rq->lock and thus can guarantee
@@ -3576,16 +3461,16 @@ static void gcwq_unbind_fn(struct work_struct *work)
 	/*
 	 * Sched callbacks are disabled now.  Zap nr_running.  After this,
 	 * nr_running stays zero and need_more_worker() and keep_working()
-	 * are always true as long as the worklist is not empty.  @gcwq now
-	 * behaves as unbound (in terms of concurrency management) gcwq
-	 * which is served by workers tied to the CPU.
+	 * are always true as long as the worklist is not empty.  Pools on
+	 * @cpu now behave as unbound (in terms of concurrency management)
+	 * pools which are served by workers tied to the CPU.
 	 *
 	 * On return from this function, the current worker would trigger
 	 * unbound chain execution of pending work items if other workers
 	 * didn't already.
 	 */
-	for_each_worker_pool(pool, gcwq)
-		atomic_set(get_pool_nr_running(pool), 0);
+	for_each_std_worker_pool(pool, cpu)
+		atomic_set(&pool->nr_running, 0);
 }
 
 /*
@@ -3597,12 +3482,11 @@ static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb,
 					       void *hcpu)
 {
 	unsigned int cpu = (unsigned long)hcpu;
-	struct global_cwq *gcwq = get_gcwq(cpu);
 	struct worker_pool *pool;
 
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_UP_PREPARE:
-		for_each_worker_pool(pool, gcwq) {
+		for_each_std_worker_pool(pool, cpu) {
 			struct worker *worker;
 
 			if (pool->nr_workers)
@@ -3612,18 +3496,24 @@ static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb,
 			if (!worker)
 				return NOTIFY_BAD;
 
-			spin_lock_irq(&gcwq->lock);
+			spin_lock_irq(&pool->lock);
 			start_worker(worker);
-			spin_unlock_irq(&gcwq->lock);
+			spin_unlock_irq(&pool->lock);
 		}
 		break;
 
 	case CPU_DOWN_FAILED:
 	case CPU_ONLINE:
-		gcwq_claim_assoc_and_lock(gcwq);
-		gcwq->flags &= ~GCWQ_DISASSOCIATED;
-		rebind_workers(gcwq);
-		gcwq_release_assoc_and_unlock(gcwq);
+		for_each_std_worker_pool(pool, cpu) {
+			mutex_lock(&pool->assoc_mutex);
+			spin_lock_irq(&pool->lock);
+
+			pool->flags &= ~POOL_DISASSOCIATED;
+			rebind_workers(pool);
+
+			spin_unlock_irq(&pool->lock);
+			mutex_unlock(&pool->assoc_mutex);
+		}
 		break;
 	}
 	return NOTIFY_OK;
@@ -3643,7 +3533,7 @@ static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb,
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_DOWN_PREPARE:
 		/* unbinding should happen on the local CPU */
-		INIT_WORK_ONSTACK(&unbind_work, gcwq_unbind_fn);
+		INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn);
 		queue_work_on(cpu, system_highpri_wq, &unbind_work);
 		flush_work(&unbind_work);
 		break;
@@ -3696,10 +3586,10 @@ EXPORT_SYMBOL_GPL(work_on_cpu);
  *
  * Start freezing workqueues.  After this function returns, all freezable
  * workqueues will queue new works to their frozen_works list instead of
- * gcwq->worklist.
+ * pool->worklist.
  *
  * CONTEXT:
- * Grabs and releases workqueue_lock and gcwq->lock's.
+ * Grabs and releases workqueue_lock and pool->lock's.
  */
 void freeze_workqueues_begin(void)
 {
@@ -3710,23 +3600,26 @@ void freeze_workqueues_begin(void)
 	BUG_ON(workqueue_freezing);
 	workqueue_freezing = true;
 
-	for_each_gcwq_cpu(cpu) {
-		struct global_cwq *gcwq = get_gcwq(cpu);
+	for_each_wq_cpu(cpu) {
+		struct worker_pool *pool;
 		struct workqueue_struct *wq;
 
-		spin_lock_irq(&gcwq->lock);
+		for_each_std_worker_pool(pool, cpu) {
+			spin_lock_irq(&pool->lock);
 
-		BUG_ON(gcwq->flags & GCWQ_FREEZING);
-		gcwq->flags |= GCWQ_FREEZING;
+			WARN_ON_ONCE(pool->flags & POOL_FREEZING);
+			pool->flags |= POOL_FREEZING;
 
-		list_for_each_entry(wq, &workqueues, list) {
-			struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+			list_for_each_entry(wq, &workqueues, list) {
+				struct pool_workqueue *pwq = get_pwq(cpu, wq);
 
-			if (cwq && wq->flags & WQ_FREEZABLE)
-				cwq->max_active = 0;
-		}
+				if (pwq && pwq->pool == pool &&
+				    (wq->flags & WQ_FREEZABLE))
+					pwq->max_active = 0;
+			}
 
-		spin_unlock_irq(&gcwq->lock);
+			spin_unlock_irq(&pool->lock);
+		}
 	}
 
 	spin_unlock(&workqueue_lock);
@@ -3754,20 +3647,20 @@ bool freeze_workqueues_busy(void)
 
 	BUG_ON(!workqueue_freezing);
 
-	for_each_gcwq_cpu(cpu) {
+	for_each_wq_cpu(cpu) {
 		struct workqueue_struct *wq;
 		/*
 		 * nr_active is monotonically decreasing.  It's safe
 		 * to peek without lock.
 		 */
 		list_for_each_entry(wq, &workqueues, list) {
-			struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+			struct pool_workqueue *pwq = get_pwq(cpu, wq);
 
-			if (!cwq || !(wq->flags & WQ_FREEZABLE))
+			if (!pwq || !(wq->flags & WQ_FREEZABLE))
 				continue;
 
-			BUG_ON(cwq->nr_active < 0);
-			if (cwq->nr_active) {
+			BUG_ON(pwq->nr_active < 0);
+			if (pwq->nr_active) {
 				busy = true;
 				goto out_unlock;
 			}
@@ -3782,10 +3675,10 @@ bool freeze_workqueues_busy(void)
  * thaw_workqueues - thaw workqueues
  *
  * Thaw workqueues.  Normal queueing is restored and all collected
- * frozen works are transferred to their respective gcwq worklists.
+ * frozen works are transferred to their respective pool worklists.
  *
  * CONTEXT:
- * Grabs and releases workqueue_lock and gcwq->lock's.
+ * Grabs and releases workqueue_lock and pool->lock's.
  */
 void thaw_workqueues(void)
 {
@@ -3796,30 +3689,31 @@ void thaw_workqueues(void)
 	if (!workqueue_freezing)
 		goto out_unlock;
 
-	for_each_gcwq_cpu(cpu) {
-		struct global_cwq *gcwq = get_gcwq(cpu);
+	for_each_wq_cpu(cpu) {
 		struct worker_pool *pool;
 		struct workqueue_struct *wq;
 
-		spin_lock_irq(&gcwq->lock);
+		for_each_std_worker_pool(pool, cpu) {
+			spin_lock_irq(&pool->lock);
 
-		BUG_ON(!(gcwq->flags & GCWQ_FREEZING));
-		gcwq->flags &= ~GCWQ_FREEZING;
+			WARN_ON_ONCE(!(pool->flags & POOL_FREEZING));
+			pool->flags &= ~POOL_FREEZING;
 
-		list_for_each_entry(wq, &workqueues, list) {
-			struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
+			list_for_each_entry(wq, &workqueues, list) {
+				struct pool_workqueue *pwq = get_pwq(cpu, wq);
 
-			if (!cwq || !(wq->flags & WQ_FREEZABLE))
-				continue;
+				if (!pwq || pwq->pool != pool ||
+				    !(wq->flags & WQ_FREEZABLE))
+					continue;
 
-			/* restore max_active and repopulate worklist */
-			cwq_set_max_active(cwq, wq->saved_max_active);
-		}
+				/* restore max_active and repopulate worklist */
+				pwq_set_max_active(pwq, wq->saved_max_active);
+			}
 
-		for_each_worker_pool(pool, gcwq)
 			wake_up_worker(pool);
 
-		spin_unlock_irq(&gcwq->lock);
+			spin_unlock_irq(&pool->lock);
+		}
 	}
 
 	workqueue_freezing = false;
@@ -3831,60 +3725,56 @@ void thaw_workqueues(void)
 static int __init init_workqueues(void)
 {
 	unsigned int cpu;
-	int i;
 
-	/* make sure we have enough bits for OFFQ CPU number */
-	BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_CPU_SHIFT)) <
-		     WORK_CPU_LAST);
+	/* make sure we have enough bits for OFFQ pool ID */
+	BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT)) <
+		     WORK_CPU_END * NR_STD_WORKER_POOLS);
 
 	cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
 	hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN);
 
-	/* initialize gcwqs */
-	for_each_gcwq_cpu(cpu) {
-		struct global_cwq *gcwq = get_gcwq(cpu);
+	/* initialize CPU pools */
+	for_each_wq_cpu(cpu) {
 		struct worker_pool *pool;
 
-		spin_lock_init(&gcwq->lock);
-		gcwq->cpu = cpu;
-		gcwq->flags |= GCWQ_DISASSOCIATED;
-
-		for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++)
-			INIT_HLIST_HEAD(&gcwq->busy_hash[i]);
-
-		for_each_worker_pool(pool, gcwq) {
-			pool->gcwq = gcwq;
+		for_each_std_worker_pool(pool, cpu) {
+			spin_lock_init(&pool->lock);
+			pool->cpu = cpu;
+			pool->flags |= POOL_DISASSOCIATED;
 			INIT_LIST_HEAD(&pool->worklist);
 			INIT_LIST_HEAD(&pool->idle_list);
+			hash_init(pool->busy_hash);
 
 			init_timer_deferrable(&pool->idle_timer);
 			pool->idle_timer.function = idle_worker_timeout;
 			pool->idle_timer.data = (unsigned long)pool;
 
-			setup_timer(&pool->mayday_timer, gcwq_mayday_timeout,
+			setup_timer(&pool->mayday_timer, pool_mayday_timeout,
 				    (unsigned long)pool);
 
 			mutex_init(&pool->assoc_mutex);
 			ida_init(&pool->worker_ida);
+
+			/* alloc pool ID */
+			BUG_ON(worker_pool_assign_id(pool));
 		}
 	}
 
 	/* create the initial worker */
-	for_each_online_gcwq_cpu(cpu) {
-		struct global_cwq *gcwq = get_gcwq(cpu);
+	for_each_online_wq_cpu(cpu) {
 		struct worker_pool *pool;
 
-		if (cpu != WORK_CPU_UNBOUND)
-			gcwq->flags &= ~GCWQ_DISASSOCIATED;
-
-		for_each_worker_pool(pool, gcwq) {
+		for_each_std_worker_pool(pool, cpu) {
 			struct worker *worker;
 
+			if (cpu != WORK_CPU_UNBOUND)
+				pool->flags &= ~POOL_DISASSOCIATED;
+
 			worker = create_worker(pool);
 			BUG_ON(!worker);
-			spin_lock_irq(&gcwq->lock);
+			spin_lock_irq(&pool->lock);
 			start_worker(worker);
-			spin_unlock_irq(&gcwq->lock);
+			spin_unlock_irq(&pool->lock);
 		}
 	}
 

kernel/workqueue_internal.h

+/*
+ * kernel/workqueue_internal.h
+ *
+ * Workqueue internal header file.  Only to be included by workqueue and
+ * core kernel subsystems.
+ */
+#ifndef _KERNEL_WORKQUEUE_INTERNAL_H
+#define _KERNEL_WORKQUEUE_INTERNAL_H
+
+#include <linux/workqueue.h>
+#include <linux/kthread.h>
+
+struct worker_pool;
+
+/*
+ * The poor guys doing the actual heavy lifting.  All on-duty workers are
+ * either serving the manager role, on idle list or on busy hash.  For
+ * details on the locking annotation (L, I, X...), refer to workqueue.c.
+ *
+ * Only to be used in workqueue and async.
+ */
+struct worker {
+	/* on idle list while idle, on busy hash table while busy */
+	union {
+		struct list_head	entry;	/* L: while idle */
+		struct hlist_node	hentry;	/* L: while busy */
+	};
+
+	struct work_struct	*current_work;	/* L: work being processed */
+	work_func_t		current_func;	/* L: current_work's fn */
+	struct pool_workqueue	*current_pwq; /* L: current_work's pwq */
+	struct list_head	scheduled;	/* L: scheduled works */
+	struct task_struct	*task;		/* I: worker task */
+	struct worker_pool	*pool;		/* I: the associated pool */
+	/* 64 bytes boundary on 64bit, 32 on 32bit */
+	unsigned long		last_active;	/* L: last active timestamp */
+	unsigned int		flags;		/* X: flags */
+	int			id;		/* I: worker id */
+
+	/* for rebinding worker to CPU */
+	struct work_struct	rebind_work;	/* L: for busy worker */
+
+	/* used only by rescuers to point to the target workqueue */
+	struct workqueue_struct	*rescue_wq;	/* I: the workqueue to rescue */
+};
+
+/**
+ * current_wq_worker - return struct worker if %current is a workqueue worker
+ */
+static inline struct worker *current_wq_worker(void)
+{
+	if (current->flags & PF_WQ_WORKER)
+		return kthread_data(current);
+	return NULL;
+}
+
+/*
+ * Scheduler hooks for concurrency managed workqueue.  Only to be used from
+ * sched.c and workqueue.c.
+ */
+void wq_worker_waking_up(struct task_struct *task, unsigned int cpu);
+struct task_struct *wq_worker_sleeping(struct task_struct *task,
+				       unsigned int cpu);
+
+#endif /* _KERNEL_WORKQUEUE_INTERNAL_H */

kernel/workqueue_sched.h

-/*
- * kernel/workqueue_sched.h
- *
- * Scheduler hooks for concurrency managed workqueue.  Only to be
- * included from sched.c and workqueue.c.
- */
-void wq_worker_waking_up(struct task_struct *task, unsigned int cpu);
-struct task_struct *wq_worker_sleeping(struct task_struct *task,
-				       unsigned int cpu);