Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Ingo Molnar:
 "The main changes are:

   - Documentation updates, including fixes to the design-level
     requirements documentation and a fixed version of the design-level
     data-structure documentation.  These fixes include removing
     cartoons and getting rid of the html/htmlx duplication.

   - Further improvements to the new-age expedited grace periods.

   - Miscellaneous fixes.

   - Torture-test changes, including a new rcuperf module for measuring
     RCU grace-period performance and scalability, which is useful for
     the expedited-grace-period changes"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (56 commits)
  rcutorture: Add boot-time adjustment of leaf fanout
  rcutorture: Add irqs-disabled test for call_rcu()
  rcutorture: Dump trace buffer upon shutdown
  rcutorture: Don't rebuild identical kernel
  rcutorture: Add OS-jitter capability
  documentation: Add documentation for RCU's major data structures
  rcutorture: Convert test duration to seconds early
  torture: Kill qemu, not parent process
  torture: Clarify refusal to run more than one torture test
  rcutorture: Consider FROZEN hotplug notifier transitions
  rcutorture: Remove redundant initialization to zero
  rcuperf: Do not wake up shutdown wait queue if "shutdown" is false.
  rcutorture: Add largish-system rcuperf scenario
  rcutorture: Avoid RCU CPU stall warning and RT throttling
  rcutorture: Add rcuperf holdoff boot parameter to reduce interference
  rcutorture: Make scripts analyze rcuperf trace data, if present
  rcutorture: Make rcuperf collect expedited event-trace data
  rcutorture: Print measure of batching efficiency
  rcutorture: Set rcuperf writer kthreads to real-time priority
  rcutorture: Bind rcuperf reader/writer kthreads to CPUs
  ...

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+       text-anchor="middle"
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+       id="text56">6:7  </text>
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Documentation/RCU/trace.txt

@@ -237,17 +237,17 @@ o	"ktl" is the low-order 16 bits (in hexadecimal) of the count of
 
 The output of "cat rcu/rcu_preempt/rcuexp" looks as follows:
 
-s=21872 wd0=0 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872
+s=21872 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872
 
 These fields are as follows:
 
 o	"s" is the sequence number, with an odd number indicating that
 	an expedited grace period is in progress.
 
-o	"wd0", "wd1", "wd2", and "wd3" are the number of times that an
-	attempt to start an expedited grace period found that someone
-	else had completed an expedited grace period that satisfies the
-	attempted request.  "Our work is done."
+o	"wd1", "wd2", and "wd3" are the number of times that an attempt
+	to start an expedited grace period found that someone else had
+	completed an expedited grace period that satisfies the attempted
+	request.  "Our work is done."
 
 o	"n" is number of times that a concurrent CPU-hotplug operation
 	forced a fallback to a normal grace period.

Documentation/RCU/whatisRCU.txt

@@ -681,22 +681,30 @@ Although RCU can be used in many different ways, a very common use of
 RCU is analogous to reader-writer locking.  The following unified
 diff shows how closely related RCU and reader-writer locking can be.
 
+	@@ -5,5 +5,5 @@ struct el {
+	 	int data;
+	 	/* Other data fields */
+	 };
+	-rwlock_t listmutex;
+	+spinlock_t listmutex;
+	 struct el head;
+
 	@@ -13,15 +14,15 @@
 		struct list_head *lp;
 		struct el *p;
 
-	-	read_lock();
+	-	read_lock(&listmutex);
 	-	list_for_each_entry(p, head, lp) {
 	+	rcu_read_lock();
 	+	list_for_each_entry_rcu(p, head, lp) {
 			if (p->key == key) {
 				*result = p->data;
-	-			read_unlock();
+	-			read_unlock(&listmutex);
 	+			rcu_read_unlock();
 				return 1;
 			}
 		}
-	-	read_unlock();
+	-	read_unlock(&listmutex);
 	+	rcu_read_unlock();
 		return 0;
 	 }
@@ -732,7 +740,7 @@ Or, for those who prefer a side-by-side listing:
  5   int data;                          5   int data;
  6   /* Other data fields */            6   /* Other data fields */
  7 };                                   7 };
- 8 spinlock_t listmutex;                8 spinlock_t listmutex;
+ 8 rwlock_t listmutex;                  8 spinlock_t listmutex;
  9 struct el head;                      9 struct el head;
 
  1 int search(long key, int *result)    1 int search(long key, int *result)
@@ -740,15 +748,15 @@ Or, for those who prefer a side-by-side listing:
  3   struct list_head *lp;              3   struct list_head *lp;
  4   struct el *p;                      4   struct el *p;
  5                                      5
- 6   read_lock();                       6   rcu_read_lock();
+ 6   read_lock(&listmutex);             6   rcu_read_lock();
  7   list_for_each_entry(p, head, lp) { 7   list_for_each_entry_rcu(p, head, lp) {
  8     if (p->key == key) {             8     if (p->key == key) {
  9       *result = p->data;             9       *result = p->data;
-10       read_unlock();                10       rcu_read_unlock();
+10       read_unlock(&listmutex);      10       rcu_read_unlock();
 11       return 1;                     11       return 1;
 12     }                               12     }
 13   }                                 13   }
-14   read_unlock();                    14   rcu_read_unlock();
+14   read_unlock(&listmutex);          14   rcu_read_unlock();
 15   return 0;                         15   return 0;
 16 }                                   16 }
 

include/linux/rcutree.h

@@ -87,6 +87,8 @@ unsigned long rcu_batches_started_sched(void);
 unsigned long rcu_batches_completed(void);
 unsigned long rcu_batches_completed_bh(void);
 unsigned long rcu_batches_completed_sched(void);
+unsigned long rcu_exp_batches_completed(void);
+unsigned long rcu_exp_batches_completed_sched(void);
 void show_rcu_gp_kthreads(void);
 
 void rcu_force_quiescent_state(void);

tools/testing/selftests/rcutorture/configs/rcu/TREE04.boot

-rcutorture.torture_type=rcu_bh
+rcutorture.torture_type=rcu_bh rcutree.rcu_fanout_leaf=4

tools/testing/selftests/rcutorture/configs/rcuperf/CFLIST

+TREE

tools/testing/selftests/rcutorture/configs/rcuperf/CFcommon

+CONFIG_RCU_PERF_TEST=y
+CONFIG_PRINTK_TIME=y