Merge branches 'doc.2019.01.26a', 'fixes.2019.01.26a', 'sil.2019.01.26a',...

Merge branches 'doc.2019.01.26a', 'fixes.2019.01.26a', 'sil.2019.01.26a', 'spdx.2019.02.09a', 'srcu.2019.01.26a' and 'torture.2019.01.26a' into HEAD

doc.2019.01.26a:  Documentation updates.
fixes.2019.01.26a:  Miscellaneous fixes.
sil.2019.01.26a:  Removal of a few more spin_is_locked() instances.
spdx.2019.02.09a:  Add SPDX identifiers to RCU files
srcu.2019.01.26a:  SRCU updates.
torture.2019.01.26a: Torture-test updates.

Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html

@@ -485,13 +485,13 @@ section that the grace period must wait on.
 noted by <tt>rcu_node_context_switch()</tt> on the left.
 On the other hand, if the CPU takes a scheduler-clock interrupt
 while executing in usermode, a quiescent state will be noted by
-<tt>rcu_check_callbacks()</tt> on the right.
+<tt>rcu_sched_clock_irq()</tt> on the right.
 Either way, the passage through a quiescent state will be noted
 in a per-CPU variable.
 
 <p>The next time an <tt>RCU_SOFTIRQ</tt> handler executes on
 this CPU (for example, after the next scheduler-clock
-interrupt), <tt>__rcu_process_callbacks()</tt> will invoke
+interrupt), <tt>rcu_core()</tt> will invoke
 <tt>rcu_check_quiescent_state()</tt>, which will notice the
 recorded quiescent state, and invoke
 <tt>rcu_report_qs_rdp()</tt>.
@@ -651,7 +651,7 @@ to end.
 These callbacks are identified by <tt>rcu_advance_cbs()</tt>,
 which is usually invoked by <tt>__note_gp_changes()</tt>.
 As shown in the diagram below, this invocation can be triggered by
-the scheduling-clock interrupt (<tt>rcu_check_callbacks()</tt> on
+the scheduling-clock interrupt (<tt>rcu_sched_clock_irq()</tt> on
 the left) or by idle entry (<tt>rcu_cleanup_after_idle()</tt> on
 the right, but only for kernels build with
 <tt>CONFIG_RCU_FAST_NO_HZ=y</tt>).

Documentation/RCU/Design/Memory-Ordering/TreeRCU-callback-invocation.svg

@@ -349,7 +349,7 @@
        font-weight="bold"
        font-size="192"
        id="text202-7-5"
-       style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_check_callbacks()</text>
+       style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_sched_clock_irq()</text>
     <rect
        x="7069.6187"
        y="5087.4678"

Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg

@@ -3902,7 +3902,7 @@
          font-style="normal"
          y="-4418.6582"
          x="3745.7725"
-         xml:space="preserve">rcu_check_callbacks()</text>
+         xml:space="preserve">rcu_sched_clock_irq()</text>
     </g>
     <g
        transform="translate(-850.30204,55463.106)"
@@ -3924,7 +3924,7 @@
          font-style="normal"
          y="-4418.6582"
          x="3745.7725"
-         xml:space="preserve">rcu_process_callbacks()</text>
+         xml:space="preserve">rcu_core()</text>
       <text
          style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier"
          id="text202-7-5-3-27-0"
@@ -3933,7 +3933,7 @@
          font-style="normal"
          y="-4165.7954"
          x="3745.7725"
-         xml:space="preserve">rcu_check_quiescent_state())</text>
+         xml:space="preserve">rcu_check_quiescent_state()</text>
       <text
          style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier"
          id="text202-7-5-3-27-0-9"
@@ -4968,7 +4968,7 @@
        font-weight="bold"
        font-size="192"
        id="text202-7-5-19"
-       style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_check_callbacks()</text>
+       style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier">rcu_sched_clock_irq()</text>
     <rect
        x="5314.2671"
        y="82817.688"

Documentation/RCU/Design/Memory-Ordering/TreeRCU-qs.svg

@@ -775,7 +775,7 @@
          font-style="normal"
          y="-4418.6582"
          x="3745.7725"
-         xml:space="preserve">rcu_check_callbacks()</text>
+         xml:space="preserve">rcu_sched_clock_irq()</text>
     </g>
     <g
        transform="translate(399.7744,828.86448)"
@@ -797,7 +797,7 @@
          font-style="normal"
          y="-4418.6582"
          x="3745.7725"
-         xml:space="preserve">rcu_process_callbacks()</text>
+         xml:space="preserve">rcu_core()</text>
       <text
          style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier"
          id="text202-7-5-3-27-0"
@@ -806,7 +806,7 @@
          font-style="normal"
          y="-4165.7954"
          x="3745.7725"
-         xml:space="preserve">rcu_check_quiescent_state())</text>
+         xml:space="preserve">rcu_check_quiescent_state()</text>
       <text
          style="font-size:192px;font-style:normal;font-weight:bold;text-anchor:start;fill:#000000;stroke-width:0.025in;font-family:Courier"
          id="text202-7-5-3-27-0-9"

Documentation/RCU/torture.txt

@@ -10,173 +10,8 @@ status messages via printk(), which can be examined via the dmesg
 command (perhaps grepping for "torture").  The test is started
 when the module is loaded, and stops when the module is unloaded.
 
-
-MODULE PARAMETERS
-
-This module has the following parameters:
-
-fqs_duration	Duration (in microseconds) of artificially induced bursts
-		of force_quiescent_state() invocations.  In RCU
-		implementations having force_quiescent_state(), these
-		bursts help force races between forcing a given grace
-		period and that grace period ending on its own.
-
-fqs_holdoff	Holdoff time (in microseconds) between consecutive calls
-		to force_quiescent_state() within a burst.
-
-fqs_stutter	Wait time (in seconds) between consecutive bursts
-		of calls to force_quiescent_state().
-
-gp_normal	Make the fake writers use normal synchronous grace-period
-		primitives.
-
-gp_exp		Make the fake writers use expedited synchronous grace-period
-		primitives.  If both gp_normal and gp_exp are set, or
-		if neither gp_normal nor gp_exp are set, then randomly
-		choose the primitive so that about 50% are normal and
-		50% expedited.  By default, neither are set, which
-		gives best overall test coverage.
-
-irqreader	Says to invoke RCU readers from irq level.  This is currently
-		done via timers.  Defaults to "1" for variants of RCU that
-		permit this.  (Or, more accurately, variants of RCU that do
-		-not- permit this know to ignore this variable.)
-
-n_barrier_cbs	If this is nonzero, RCU barrier testing will be conducted,
-		in which case n_barrier_cbs specifies the number of
-		RCU callbacks (and corresponding kthreads) to use for
-		this testing.  The value cannot be negative.  If you
-		specify this to be non-zero when torture_type indicates a
-		synchronous RCU implementation (one for which a member of
-		the synchronize_rcu() rather than the call_rcu() family is
-		used -- see the documentation for torture_type below), an
-		error will be reported and no testing will be carried out.
-
-nfakewriters	This is the number of RCU fake writer threads to run.  Fake
-		writer threads repeatedly use the synchronous "wait for
-		current readers" function of the interface selected by
-		torture_type, with a delay between calls to allow for various
-		different numbers of writers running in parallel.
-		nfakewriters defaults to 4, which provides enough parallelism
-		to trigger special cases caused by multiple writers, such as
-		the synchronize_srcu() early return optimization.
-
-nreaders	This is the number of RCU reading threads supported.
-		The default is twice the number of CPUs.  Why twice?
-		To properly exercise RCU implementations with preemptible
-		read-side critical sections.
-
-onoff_interval
-		The number of seconds between each attempt to execute a
-		randomly selected CPU-hotplug operation.  Defaults to
-		zero, which disables CPU hotplugging.  In HOTPLUG_CPU=n
-		kernels, rcutorture will silently refuse to do any
-		CPU-hotplug operations regardless of what value is
-		specified for onoff_interval.
-
-onoff_holdoff	The number of seconds to wait until starting CPU-hotplug
-		operations.  This would normally only be used when
-		rcutorture was built into the kernel and started
-		automatically at boot time, in which case it is useful
-		in order to avoid confusing boot-time code with CPUs
-		coming and going.
-
-shuffle_interval
-		The number of seconds to keep the test threads affinitied
-		to a particular subset of the CPUs, defaults to 3 seconds.
-		Used in conjunction with test_no_idle_hz.
-
-shutdown_secs	The number of seconds to run the test before terminating
-		the test and powering off the system.  The default is
-		zero, which disables test termination and system shutdown.
-		This capability is useful for automated testing.
-
-stall_cpu	The number of seconds that a CPU should be stalled while
-		within both an rcu_read_lock() and a preempt_disable().
-		This stall happens only once per rcutorture run.
-		If you need multiple stalls, use modprobe and rmmod to
-		repeatedly run rcutorture.  The default for stall_cpu
-		is zero, which prevents rcutorture from stalling a CPU.
-
-		Note that attempts to rmmod rcutorture while the stall
-		is ongoing will hang, so be careful what value you
-		choose for this module parameter!  In addition, too-large
-		values for stall_cpu might well induce failures and
-		warnings in other parts of the kernel.  You have been
-		warned!
-
-stall_cpu_holdoff
-		The number of seconds to wait after rcutorture starts
-		before stalling a CPU.  Defaults to 10 seconds.
-
-stat_interval	The number of seconds between output of torture
-		statistics (via printk()).  Regardless of the interval,
-		statistics are printed when the module is unloaded.
-		Setting the interval to zero causes the statistics to
-		be printed -only- when the module is unloaded, and this
-		is the default.
-
-stutter		The length of time to run the test before pausing for this
-		same period of time.  Defaults to "stutter=5", so as
-		to run and pause for (roughly) five-second intervals.
-		Specifying "stutter=0" causes the test to run continuously
-		without pausing, which is the old default behavior.
-
-test_boost	Whether or not to test the ability of RCU to do priority
-		boosting.  Defaults to "test_boost=1", which performs
-		RCU priority-inversion testing only if the selected
-		RCU implementation supports priority boosting.  Specifying
-		"test_boost=0" never performs RCU priority-inversion
-		testing.  Specifying "test_boost=2" performs RCU
-		priority-inversion testing even if the selected RCU
-		implementation does not support RCU priority boosting,
-		which can be used to test rcutorture's ability to
-		carry out RCU priority-inversion testing.
-
-test_boost_interval
-		The number of seconds in an RCU priority-inversion test
-		cycle.	Defaults to "test_boost_interval=7".  It is
-		usually wise for this value to be relatively prime to
-		the value selected for "stutter".
-
-test_boost_duration
-		The number of seconds to do RCU priority-inversion testing
-		within any given "test_boost_interval".  Defaults to
-		"test_boost_duration=4".
-
-test_no_idle_hz	Whether or not to test the ability of RCU to operate in
-		a kernel that disables the scheduling-clock interrupt to
-		idle CPUs.  Boolean parameter, "1" to test, "0" otherwise.
-		Defaults to omitting this test.
-
-torture_type	The type of RCU to test, with string values as follows:
-
-		"rcu":  rcu_read_lock(), rcu_read_unlock() and call_rcu(),
-			along with expedited, synchronous, and polling
-			variants.
-
-		"rcu_bh": rcu_read_lock_bh(), rcu_read_unlock_bh(), and
-			call_rcu_bh(), along with expedited and synchronous
-			variants.
-
-		"rcu_busted": This tests an intentionally incorrect version
-			of RCU in order to help test rcutorture itself.
-
-		"srcu": srcu_read_lock(), srcu_read_unlock() and
-			call_srcu(), along with expedited and
-			synchronous variants.
-
-		"sched": preempt_disable(), preempt_enable(), and
-			call_rcu_sched(), along with expedited,
-			synchronous, and polling variants.
-
-		"tasks": voluntary context switch and call_rcu_tasks(),
-			along with expedited and synchronous variants.
-
-		Defaults to "rcu".
-
-verbose		Enable debug printk()s.  Default is disabled.
-
+Module parameters are prefixed by "rcutorture." in
+Documentation/admin-guide/kernel-parameters.txt.
 
 OUTPUT
 

MAINTAINERS

@@ -10791,6 +10791,12 @@ F:	drivers/power/supply/bq27xxx_battery_i2c.c
 F:	drivers/power/supply/isp1704_charger.c
 F:	drivers/power/supply/rx51_battery.c
 
+NOLIBC HEADER FILE
+M:	Willy Tarreau <w@1wt.eu>
+S:	Maintained
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/nolibc.git
+F:	tools/include/nolibc/
+
 NTB AMD DRIVER
 M:	Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
 L:	linux-ntb@googlegroups.com

include/asm-generic/bug.h

@@ -211,9 +211,6 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 /*
  * WARN_ON_SMP() is for cases that the warning is either
  * meaningless for !SMP or may even cause failures.
- * This is usually used for cases that we have
- * WARN_ON(!spin_is_locked(&lock)) checks, as spin_is_locked()
- * returns 0 for uniprocessor settings.
  * It can also be used with values that are only defined
  * on SMP:
  *

include/linux/rcu_node_tree.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * RCU node combining tree definitions.  These are used to compute
  * global attributes while avoiding common-case global contention.  A key
@@ -11,23 +12,9 @@
  * because the size of the TREE SRCU srcu_struct structure depends
  * on these definitions.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2017
  *
- * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Author: Paul E. McKenney <paulmck@linux.ibm.com>
  */
 
 #ifndef __LINUX_RCU_NODE_TREE_H

include/linux/rcu_segcblist.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * RCU segmented callback lists
  *
@@ -5,23 +6,9 @@
  * because the size of the TREE SRCU srcu_struct structure depends
  * on these definitions.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2017
  *
- * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.net.ibm.com>
  */
 
 #ifndef __INCLUDE_LINUX_RCU_SEGCBLIST_H

include/linux/rcu_sync.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * RCU-based infrastructure for lightweight reader-writer locking
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (c) 2015, Red Hat, Inc.
  *
  * Author: Oleg Nesterov <oleg@redhat.com>

include/linux/rcupdate.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Read-Copy Update mechanism for mutual exclusion
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2001
  *
  * Author: Dipankar Sarma <dipankar@in.ibm.com>
  *
- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
+ * Based on the original work by Paul McKenney <paulmck@vnet.ibm.com>
  * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
  * Papers:
  * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
@@ -89,7 +76,7 @@ static inline int rcu_preempt_depth(void)
 /* Internal to kernel */
 void rcu_init(void);
 extern int rcu_scheduler_active __read_mostly;
-void rcu_check_callbacks(int user);
+void rcu_sched_clock_irq(int user);
 void rcu_report_dead(unsigned int cpu);
 void rcutree_migrate_callbacks(int cpu);
 
@@ -309,16 +296,16 @@ static inline void rcu_preempt_sleep_check(void) { }
  */
 
 #ifdef __CHECKER__
-#define rcu_dereference_sparse(p, space) \
+#define rcu_check_sparse(p, space) \
 	((void)(((typeof(*p) space *)p) == p))
 #else /* #ifdef __CHECKER__ */
-#define rcu_dereference_sparse(p, space)
+#define rcu_check_sparse(p, space)
 #endif /* #else #ifdef __CHECKER__ */
 
 #define __rcu_access_pointer(p, space) \
 ({ \
 	typeof(*p) *_________p1 = (typeof(*p) *__force)READ_ONCE(p); \
-	rcu_dereference_sparse(p, space); \
+	rcu_check_sparse(p, space); \
 	((typeof(*p) __force __kernel *)(_________p1)); \
 })
 #define __rcu_dereference_check(p, c, space) \
@@ -326,13 +313,13 @@ static inline void rcu_preempt_sleep_check(void) { }
 	/* Dependency order vs. p above. */ \
 	typeof(*p) *________p1 = (typeof(*p) *__force)READ_ONCE(p); \
 	RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_check() usage"); \
-	rcu_dereference_sparse(p, space); \
+	rcu_check_sparse(p, space); \
 	((typeof(*p) __force __kernel *)(________p1)); \
 })
 #define __rcu_dereference_protected(p, c, space) \
 ({ \
 	RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_protected() usage"); \
-	rcu_dereference_sparse(p, space); \
+	rcu_check_sparse(p, space); \
 	((typeof(*p) __force __kernel *)(p)); \
 })
 #define rcu_dereference_raw(p) \
@@ -382,6 +369,7 @@ static inline void rcu_preempt_sleep_check(void) { }
 #define rcu_assign_pointer(p, v)					      \
 ({									      \
 	uintptr_t _r_a_p__v = (uintptr_t)(v);				      \
+	rcu_check_sparse(p, __rcu);				      \
 									      \
 	if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL)	      \
 		WRITE_ONCE((p), (typeof(p))(_r_a_p__v));		      \
@@ -785,7 +773,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
  */
 #define RCU_INIT_POINTER(p, v) \
 	do { \
-		rcu_dereference_sparse(p, __rcu); \
+		rcu_check_sparse(p, __rcu); \
 		WRITE_ONCE(p, RCU_INITIALIZER(v)); \
 	} while (0)
 
@@ -859,7 +847,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
 
 /* Has the specified rcu_head structure been handed to call_rcu()? */
 
-/*
+/**
  * rcu_head_init - Initialize rcu_head for rcu_head_after_call_rcu()
  * @rhp: The rcu_head structure to initialize.
  *
@@ -874,10 +862,10 @@ static inline void rcu_head_init(struct rcu_head *rhp)
 	rhp->func = (rcu_callback_t)~0L;
 }
 
-/*
+/**
  * rcu_head_after_call_rcu - Has this rcu_head been passed to call_rcu()?
  * @rhp: The rcu_head structure to test.
- * @func: The function passed to call_rcu() along with @rhp.
+ * @f: The function passed to call_rcu() along with @rhp.
  *
  * Returns @true if the @rhp has been passed to call_rcu() with @func,
  * and @false otherwise.  Emits a warning in any other case, including

include/linux/rcutiny.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2008
  *
- * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Author: Paul E. McKenney <paulmck@linux.ibm.com>
  *
  * For detailed explanation of Read-Copy Update mechanism see -
  *		Documentation/RCU

include/linux/rcutree.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Read-Copy Update mechanism for mutual exclusion (tree-based version)
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2008
  *
  * Author: Dipankar Sarma <dipankar@in.ibm.com>
- *	   Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical algorithm
+ *	   Paul E. McKenney <paulmck@linux.ibm.com> Hierarchical algorithm
  *
- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
+ * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
  * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
  *
  * For detailed explanation of Read-Copy Update mechanism see -

include/linux/srcu.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Sleepable Read-Copy Update mechanism for mutual exclusion
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (C) IBM Corporation, 2006
  * Copyright (C) Fujitsu, 2012
  *
- * Author: Paul McKenney <paulmck@us.ibm.com>
+ * Author: Paul McKenney <paulmck@linux.ibm.com>
  *	   Lai Jiangshan <laijs@cn.fujitsu.com>
  *
  * For detailed explanation of Read-Copy Update mechanism see -
@@ -223,6 +210,7 @@ srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp)
 static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx)
 	__releases(ssp)
 {
+	WARN_ON_ONCE(idx & ~0x1);
 	rcu_lock_release(&(ssp)->dep_map);
 	__srcu_read_unlock(ssp, idx);
 }

include/linux/srcutiny.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Sleepable Read-Copy Update mechanism for mutual exclusion,
  *	tiny variant.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (C) IBM Corporation, 2017
  *
- * Author: Paul McKenney <paulmck@us.ibm.com>
+ * Author: Paul McKenney <paulmck@linux.ibm.com>
  */
 
 #ifndef _LINUX_SRCU_TINY_H

include/linux/srcutree.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Sleepable Read-Copy Update mechanism for mutual exclusion,
  *	tree variant.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (C) IBM Corporation, 2017
  *
- * Author: Paul McKenney <paulmck@us.ibm.com>
+ * Author: Paul McKenney <paulmck@linux.ibm.com>
  */
 
 #ifndef _LINUX_SRCU_TREE_H
@@ -45,7 +32,8 @@ struct srcu_data {
 	unsigned long srcu_gp_seq_needed;	/* Furthest future GP needed. */
 	unsigned long srcu_gp_seq_needed_exp;	/* Furthest future exp GP. */
 	bool srcu_cblist_invoking;		/* Invoking these CBs? */
-	struct delayed_work work;		/* Context for CB invoking. */
+	struct timer_list delay_work;		/* Delay for CB invoking */
+	struct work_struct work;		/* Context for CB invoking. */
 	struct rcu_head srcu_barrier_head;	/* For srcu_barrier() use. */
 	struct srcu_node *mynode;		/* Leaf srcu_node. */
 	unsigned long grpmask;			/* Mask for leaf srcu_node */

include/linux/torture.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Common functions for in-kernel torture tests.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2014
  *
- * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Author: Paul E. McKenney <paulmck@linux.ibm.com>
  */
 
 #ifndef __LINUX_TORTURE_H
@@ -50,11 +37,12 @@
 	do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! %s\n", torture_type, s); } while (0)
 
 /* Definitions for online/offline exerciser. */
+typedef void torture_ofl_func(void);
 bool torture_offline(int cpu, long *n_onl_attempts, long *n_onl_successes,
 		     unsigned long *sum_offl, int *min_onl, int *max_onl);
 bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
 		    unsigned long *sum_onl, int *min_onl, int *max_onl);
-int torture_onoff_init(long ooholdoff, long oointerval);
+int torture_onoff_init(long ooholdoff, long oointerval, torture_ofl_func *f);
 void torture_onoff_stats(void);
 bool torture_onoff_failures(void);
 

kernel/locking/locktorture.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Module-based torture test facility for locking
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (C) IBM Corporation, 2014
  *
- * Authors: Paul E. McKenney <paulmck@us.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
  *          Davidlohr Bueso <dave@stgolabs.net>
  *	Based on kernel/rcu/torture.c.
  */
@@ -45,7 +32,7 @@
 #include <linux/torture.h>
 
 MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
 
 torture_param(int, nwriters_stress, -1,
 	     "Number of write-locking stress-test threads");
@@ -970,7 +957,7 @@ static int __init lock_torture_init(void)
 	/* Prepare torture context. */
 	if (onoff_interval > 0) {
 		firsterr = torture_onoff_init(onoff_holdoff * HZ,
-					      onoff_interval * HZ);
+					      onoff_interval * HZ, NULL);
 		if (firsterr)
 			goto unwind;
 	}

kernel/rcu/rcu.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Read-Copy Update definitions shared among RCU implementations.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2011
  *
- * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Author: Paul E. McKenney <paulmck@linux.ibm.com>
  */
 
 #ifndef __LINUX_RCU_H
@@ -30,7 +17,7 @@
 #define RCU_TRACE(stmt)
 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 
-/* Offset to allow for unmatched rcu_irq_{enter,exit}(). */
+/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */
 #define DYNTICK_IRQ_NONIDLE	((LONG_MAX / 2) + 1)
 
 

kernel/rcu/rcu_segcblist.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * RCU segmented callback lists, function definitions
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2017
  *
- * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
  */
 
 #include <linux/types.h>

kernel/rcu/rcu_segcblist.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * RCU segmented callback lists, internal-to-rcu header file
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2017
  *
- * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
  */
 
 #include <linux/rcu_segcblist.h>

kernel/rcu/rcuperf.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Read-Copy Update module-based performance-test facility
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (C) IBM Corporation, 2015
  *
- * Authors: Paul E. McKenney <paulmck@us.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
  */
 
 #define pr_fmt(fmt) fmt
@@ -54,7 +41,7 @@
 #include "rcu.h"
 
 MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
 
 #define PERF_FLAG "-perf:"
 #define PERFOUT_STRING(s) \
@@ -83,13 +70,19 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
  * Various other use cases may of course be specified.
  */
 
+#ifdef MODULE
+# define RCUPERF_SHUTDOWN 0
+#else
+# define RCUPERF_SHUTDOWN 1
+#endif
+
 torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
 torture_param(int, gp_async_max, 1000, "Max # outstanding waits per reader");
 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
 torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
 torture_param(int, nreaders, -1, "Number of RCU reader threads");
 torture_param(int, nwriters, -1, "Number of RCU updater threads");
-torture_param(bool, shutdown, !IS_ENABLED(MODULE),
+torture_param(bool, shutdown, RCUPERF_SHUTDOWN,
 	      "Shutdown at end of performance tests.");
 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
 torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");

kernel/rcu/rcutorture.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Read-Copy Update module-based torture test facility
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (C) IBM Corporation, 2005, 2006
  *
- * Authors: Paul E. McKenney <paulmck@us.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
  *	  Josh Triplett <josh@joshtriplett.org>
  *
  * See also:  Documentation/RCU/torture.txt
@@ -61,7 +48,7 @@
 #include "rcu.h"
 
 MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
 
 
 /* Bits for ->extendables field, extendables param, and related definitions. */
@@ -1630,21 +1617,34 @@ static bool rcu_fwd_emergency_stop;
 #define MIN_FWD_CB_LAUNDERS	3	/* This many CB invocations to count. */
 #define MIN_FWD_CBS_LAUNDERED	100	/* Number of counted CBs. */
 #define FWD_CBS_HIST_DIV	10	/* Histogram buckets/second. */
-static long n_launders_hist[2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV)];
+struct rcu_launder_hist {
+	long n_launders;
+	unsigned long launder_gp_seq;
+};
+#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
+static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
+static unsigned long rcu_launder_gp_seq_start;
 
 static void rcu_torture_fwd_cb_hist(void)
 {
+	unsigned long gps;
+	unsigned long gps_old;
 	int i;
 	int j;
 
 	for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
-		if (n_launders_hist[i] > 0)
+		if (n_launders_hist[i].n_launders > 0)
 			break;
 	pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
 		 __func__, jiffies - rcu_fwd_startat);
-	for (j = 0; j <= i; j++)
-		pr_cont(" %ds/%d: %ld",
-			j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j]);
+	gps_old = rcu_launder_gp_seq_start;
+	for (j = 0; j <= i; j++) {
+		gps = n_launders_hist[j].launder_gp_seq;
+		pr_cont(" %ds/%d: %ld:%ld",
+			j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders,
+			rcutorture_seq_diff(gps, gps_old));
+		gps_old = gps;
+	}
 	pr_cont("\n");
 }
 
@@ -1666,7 +1666,8 @@ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
 	i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
 	if (i >= ARRAY_SIZE(n_launders_hist))
 		i = ARRAY_SIZE(n_launders_hist) - 1;
-	n_launders_hist[i]++;
+	n_launders_hist[i].n_launders++;
+	n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
 	spin_unlock_irqrestore(&rcu_fwd_lock, flags);
 }
 
@@ -1786,9 +1787,10 @@ static void rcu_torture_fwd_prog_cr(void)
 	n_max_cbs = 0;
 	n_max_gps = 0;
 	for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
-		n_launders_hist[i] = 0;
+		n_launders_hist[i].n_launders = 0;
 	cver = READ_ONCE(rcu_torture_current_version);
 	gps = cur_ops->get_gp_seq();
+	rcu_launder_gp_seq_start = gps;
 	while (time_before(jiffies, stopat) &&
 	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
 		rfcp = READ_ONCE(rcu_fwd_cb_head);
@@ -2228,6 +2230,14 @@ static void rcu_test_debug_objects(void)
 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
 }
 
+static void rcutorture_sync(void)
+{
+	static unsigned long n;
+
+	if (cur_ops->sync && !(++n & 0xfff))
+		cur_ops->sync();
+}
+
 static int __init
 rcu_torture_init(void)
 {
@@ -2389,7 +2399,8 @@ rcu_torture_init(void)
 	firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
 	if (firsterr)
 		goto unwind;
-	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval);
+	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
+				      rcutorture_sync);
 	if (firsterr)
 		goto unwind;
 	firsterr = rcu_torture_stall_init();

kernel/rcu/srcutiny.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Sleepable Read-Copy Update mechanism for mutual exclusion,
  *	tiny version for non-preemptible single-CPU use.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (C) IBM Corporation, 2017
  *
- * Author: Paul McKenney <paulmck@us.ibm.com>
+ * Author: Paul McKenney <paulmck@linux.ibm.com>
  */
 
 #include <linux/export.h>

kernel/rcu/srcutree.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Sleepable Read-Copy Update mechanism for mutual exclusion.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (C) IBM Corporation, 2006
  * Copyright (C) Fujitsu, 2012
  *
- * Author: Paul McKenney <paulmck@us.ibm.com>
+ * Author: Paul McKenney <paulmck@linux.ibm.com>
  *	   Lai Jiangshan <laijs@cn.fujitsu.com>
  *
  * For detailed explanation of Read-Copy Update mechanism see -
@@ -58,6 +45,7 @@ static bool __read_mostly srcu_init_done;
 static void srcu_invoke_callbacks(struct work_struct *work);
 static void srcu_reschedule(struct srcu_struct *ssp, unsigned long delay);
 static void process_srcu(struct work_struct *work);
+static void srcu_delay_timer(struct timer_list *t);
 
 /* Wrappers for lock acquisition and release, see raw_spin_lock_rcu_node(). */
 #define spin_lock_rcu_node(p)					\
@@ -156,7 +144,8 @@ static void init_srcu_struct_nodes(struct srcu_struct *ssp, bool is_static)
 			snp->grphi = cpu;
 		}
 		sdp->cpu = cpu;
-		INIT_DELAYED_WORK(&sdp->work, srcu_invoke_callbacks);
+		INIT_WORK(&sdp->work, srcu_invoke_callbacks);
+		timer_setup(&sdp->delay_work, srcu_delay_timer, 0);
 		sdp->ssp = ssp;
 		sdp->grpmask = 1 << (cpu - sdp->mynode->grplo);
 		if (is_static)
@@ -386,13 +375,19 @@ void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced)
 	} else {
 		flush_delayed_work(&ssp->work);
 	}
-	for_each_possible_cpu(cpu)
+	for_each_possible_cpu(cpu) {
+		struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu);
+
 		if (quiesced) {
-			if (WARN_ON(delayed_work_pending(&per_cpu_ptr(ssp->sda, cpu)->work)))
+			if (WARN_ON(timer_pending(&sdp->delay_work)))
+				return; /* Just leak it! */
+			if (WARN_ON(work_pending(&sdp->work)))
 				return; /* Just leak it! */
 		} else {
-			flush_delayed_work(&per_cpu_ptr(ssp->sda, cpu)->work);
+			del_timer_sync(&sdp->delay_work);
+			flush_work(&sdp->work);
 		}
+	}
 	if (WARN_ON(rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) != SRCU_STATE_IDLE) ||
 	    WARN_ON(srcu_readers_active(ssp))) {
 		pr_info("%s: Active srcu_struct %p state: %d\n",
@@ -463,39 +458,23 @@ static void srcu_gp_start(struct srcu_struct *ssp)
 	WARN_ON_ONCE(state != SRCU_STATE_SCAN1);
 }
 
-/*
- * Track online CPUs to guide callback workqueue placement.
- */
-DEFINE_PER_CPU(bool, srcu_online);
 
-void srcu_online_cpu(unsigned int cpu)
+static void srcu_delay_timer(struct timer_list *t)
 {
-	WRITE_ONCE(per_cpu(srcu_online, cpu), true);
-}
+	struct srcu_data *sdp = container_of(t, struct srcu_data, delay_work);
 
-void srcu_offline_cpu(unsigned int cpu)
-{
-	WRITE_ONCE(per_cpu(srcu_online, cpu), false);
+	queue_work_on(sdp->cpu, rcu_gp_wq, &sdp->work);
 }
 
-/*
- * Place the workqueue handler on the specified CPU if online, otherwise
- * just run it whereever.  This is useful for placing workqueue handlers
- * that are to invoke the specified CPU's callbacks.
- */
-static bool srcu_queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
-				       struct delayed_work *dwork,
+static void srcu_queue_delayed_work_on(struct srcu_data *sdp,
 				       unsigned long delay)
 {
-	bool ret;
+	if (!delay) {
+		queue_work_on(sdp->cpu, rcu_gp_wq, &sdp->work);
+		return;
+	}
 
-	preempt_disable();
-	if (READ_ONCE(per_cpu(srcu_online, cpu)))
-		ret = queue_delayed_work_on(cpu, wq, dwork, delay);
-	else
-		ret = queue_delayed_work(wq, dwork, delay);
-	preempt_enable();
-	return ret;
+	timer_reduce(&sdp->delay_work, jiffies + delay);
 }
 
 /*
@@ -504,7 +483,7 @@ static bool srcu_queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
  */
 static void srcu_schedule_cbs_sdp(struct srcu_data *sdp, unsigned long delay)
 {
-	srcu_queue_delayed_work_on(sdp->cpu, rcu_gp_wq, &sdp->work, delay);
+	srcu_queue_delayed_work_on(sdp, delay);
 }
 
 /*
@@ -1186,7 +1165,8 @@ static void srcu_invoke_callbacks(struct work_struct *work)
 	struct srcu_data *sdp;
 	struct srcu_struct *ssp;
 
-	sdp = container_of(work, struct srcu_data, work.work);
+	sdp = container_of(work, struct srcu_data, work);
+
 	ssp = sdp->ssp;
 	rcu_cblist_init(&ready_cbs);
 	spin_lock_irq_rcu_node(sdp);

kernel/rcu/sync.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * RCU-based infrastructure for lightweight reader-writer locking
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (c) 2015, Red Hat, Inc.
  *
  * Author: Oleg Nesterov <oleg@redhat.com>

kernel/rcu/tiny.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2008
  *
- * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Author: Paul E. McKenney <paulmck@linux.ibm.com>
  *
  * For detailed explanation of Read-Copy Update mechanism see -
  *		Documentation/RCU
@@ -76,7 +63,7 @@ void rcu_qs(void)
  * be called from hardirq context.  It is normally called from the
  * scheduling-clock interrupt.
  */
-void rcu_check_callbacks(int user)
+void rcu_sched_clock_irq(int user)
 {
 	if (user) {
 		rcu_qs();

kernel/rcu/tree.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Read-Copy Update mechanism for mutual exclusion
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2008
  *
  * Authors: Dipankar Sarma <dipankar@in.ibm.com>
  *	    Manfred Spraul <manfred@colorfullife.com>
- *	    Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical version
+ *	    Paul E. McKenney <paulmck@linux.ibm.com> Hierarchical version
  *
- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
+ * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
  * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
  *
  * For detailed explanation of Read-Copy Update mechanism see -
@@ -725,7 +712,6 @@ static __always_inline void rcu_nmi_exit_common(bool irq)
 
 /**
  * rcu_nmi_exit - inform RCU of exit from NMI context
- * @irq: Is this call from rcu_irq_exit?
  *
  * If you add or remove a call to rcu_nmi_exit(), be sure to test
  * with CONFIG_RCU_EQS_DEBUG=y.
@@ -1139,7 +1125,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
 	}
 
 	/*
-	 * NO_HZ_FULL CPUs can run in-kernel without rcu_check_callbacks!
+	 * NO_HZ_FULL CPUs can run in-kernel without rcu_sched_clock_irq!
 	 * The above code handles this, but only for straight cond_resched().
 	 * And some in-kernel loops check need_resched() before calling
 	 * cond_resched(), which defeats the above code for CPUs that are
@@ -2532,14 +2518,14 @@ static void rcu_do_batch(struct rcu_data *rdp)
 }
 
 /*
- * Check to see if this CPU is in a non-context-switch quiescent state
- * (user mode or idle loop for rcu, non-softirq execution for rcu_bh).
- * Also schedule RCU core processing.
- *
- * This function must be called from hardirq context.  It is normally
- * invoked from the scheduling-clock interrupt.
+ * This function is invoked from each scheduling-clock interrupt,
+ * and checks to see if this CPU is in a non-context-switch quiescent
+ * state, for example, user mode or idle loop.  It also schedules RCU
+ * core processing.  If the current grace period has gone on too long,
+ * it will ask the scheduler to manufacture a context switch for the sole
+ * purpose of providing a providing the needed quiescent state.
  */
-void rcu_check_callbacks(int user)
+void rcu_sched_clock_irq(int user)
 {
 	trace_rcu_utilization(TPS("Start scheduler-tick"));
 	raw_cpu_inc(rcu_data.ticks_this_gp);
@@ -2552,7 +2538,7 @@ void rcu_check_callbacks(int user)
 		}
 		__this_cpu_write(rcu_data.rcu_urgent_qs, false);
 	}
-	rcu_flavor_check_callbacks(user);
+	rcu_flavor_sched_clock_irq(user);
 	if (rcu_pending())
 		invoke_rcu_core();
 
@@ -2742,12 +2728,8 @@ void rcu_fwd_progress_check(unsigned long j)
 }
 EXPORT_SYMBOL_GPL(rcu_fwd_progress_check);
 
-/*
- * This does the RCU core processing work for the specified rcu_data
- * structures.  This may be called only from the CPU to whom the rdp
- * belongs.
- */
-static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
+/* Perform RCU core processing work for the current CPU.  */
+static __latent_entropy void rcu_core(struct softirq_action *unused)
 {
 	unsigned long flags;
 	struct rcu_data *rdp = raw_cpu_ptr(&rcu_data);
@@ -3408,8 +3390,6 @@ int rcutree_online_cpu(unsigned int cpu)
 	raw_spin_lock_irqsave_rcu_node(rnp, flags);
 	rnp->ffmask |= rdp->grpmask;
 	raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
-	if (IS_ENABLED(CONFIG_TREE_SRCU))
-		srcu_online_cpu(cpu);
 	if (rcu_scheduler_active == RCU_SCHEDULER_INACTIVE)
 		return 0; /* Too early in boot for scheduler work. */
 	sync_sched_exp_online_cleanup(cpu);
@@ -3434,8 +3414,6 @@ int rcutree_offline_cpu(unsigned int cpu)
 	raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
 
 	rcutree_affinity_setting(cpu, cpu);
-	if (IS_ENABLED(CONFIG_TREE_SRCU))
-		srcu_offline_cpu(cpu);
 	return 0;
 }
 
@@ -3856,7 +3834,7 @@ void __init rcu_init(void)
 	rcu_init_one();
 	if (dump_tree)
 		rcu_dump_rcu_node_tree();
-	open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+	open_softirq(RCU_SOFTIRQ, rcu_core);
 
 	/*
 	 * We don't need protection against CPU-hotplug here because

kernel/rcu/tree.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Read-Copy Update mechanism for mutual exclusion (tree-based version)
  * Internal non-public definitions.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2008
  *
  * Author: Ingo Molnar <mingo@elte.hu>
- *	   Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ *	   Paul E. McKenney <paulmck@linux.ibm.com>
  */
 
 #include <linux/cache.h>
@@ -417,7 +404,7 @@ static void rcu_print_detail_task_stall(void);
 static int rcu_print_task_stall(struct rcu_node *rnp);
 static int rcu_print_task_exp_stall(struct rcu_node *rnp);
 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
-static void rcu_flavor_check_callbacks(int user);
+static void rcu_flavor_sched_clock_irq(int user);
 void call_rcu(struct rcu_head *head, rcu_callback_t func);
 static void dump_blkd_tasks(struct rcu_node *rnp, int ncheck);
 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
@@ -458,11 +445,3 @@ static void rcu_bind_gp_kthread(void);
 static bool rcu_nohz_full_cpu(void);
 static void rcu_dynticks_task_enter(void);
 static void rcu_dynticks_task_exit(void);
-
-#ifdef CONFIG_SRCU
-void srcu_online_cpu(unsigned int cpu);
-void srcu_offline_cpu(unsigned int cpu);
-#else /* #ifdef CONFIG_SRCU */
-void srcu_online_cpu(unsigned int cpu) { }
-void srcu_offline_cpu(unsigned int cpu) { }
-#endif /* #else #ifdef CONFIG_SRCU */

kernel/rcu/tree_exp.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * RCU expedited grace periods
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2016
  *
- * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
  */
 
 #include <linux/lockdep.h>
@@ -448,7 +435,6 @@ static void sync_rcu_exp_select_cpus(void)
 			continue;
 		}
 		INIT_WORK(&rnp->rew.rew_work, sync_rcu_exp_select_node_cpus);
-		preempt_disable();
 		cpu = find_next_bit(&rnp->ffmask, BITS_PER_LONG, -1);
 		/* If all offline, queue the work on an unbound CPU. */
 		if (unlikely(cpu > rnp->grphi - rnp->grplo))
@@ -456,7 +442,6 @@ static void sync_rcu_exp_select_cpus(void)
 		else
 			cpu += rnp->grplo;
 		queue_work_on(cpu, rcu_par_gp_wq, &rnp->rew.rew_work);
-		preempt_enable();
 		rnp->exp_need_flush = true;
 	}
 

kernel/rcu/tree_plugin.h

+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Read-Copy Update mechanism for mutual exclusion (tree-based version)
  * Internal non-public definitions that provide either classic
  * or preemptible semantics.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright Red Hat, 2009
  * Copyright IBM Corporation, 2009
  *
  * Author: Ingo Molnar <mingo@elte.hu>
- *	   Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ *	   Paul E. McKenney <paulmck@linux.ibm.com>
  */
 
 #include <linux/delay.h>
@@ -297,7 +284,7 @@ static void rcu_qs(void)
 				       __this_cpu_read(rcu_data.gp_seq),
 				       TPS("cpuqs"));
 		__this_cpu_write(rcu_data.cpu_no_qs.b.norm, false);
-		barrier(); /* Coordinate with rcu_flavor_check_callbacks(). */
+		barrier(); /* Coordinate with rcu_flavor_sched_clock_irq(). */
 		current->rcu_read_unlock_special.b.need_qs = false;
 	}
 }
@@ -778,13 +765,13 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
 }
 
 /*
- * Check for a quiescent state from the current CPU.  When a task blocks,
- * the task is recorded in the corresponding CPU's rcu_node structure,
- * which is checked elsewhere.
- *
- * Caller must disable hard irqs.
+ * Check for a quiescent state from the current CPU, including voluntary
+ * context switches for Tasks RCU.  When a task blocks, the task is
+ * recorded in the corresponding CPU's rcu_node structure, which is checked
+ * elsewhere, hence this function need only check for quiescent states
+ * related to the current CPU, not to those related to tasks.
  */
-static void rcu_flavor_check_callbacks(int user)
+static void rcu_flavor_sched_clock_irq(int user)
 {
 	struct task_struct *t = current;
 
@@ -1030,14 +1017,10 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
 }
 
 /*
- * Check to see if this CPU is in a non-context-switch quiescent state
- * (user mode or idle loop for rcu, non-softirq execution for rcu_bh).
- * Also schedule RCU core processing.
- *
- * This function must be called from hardirq context.  It is normally
- * invoked from the scheduling-clock interrupt.
+ * Check to see if this CPU is in a non-context-switch quiescent state,
+ * namely user mode and idle loop.
  */
-static void rcu_flavor_check_callbacks(int user)
+static void rcu_flavor_sched_clock_irq(int user)
 {
 	if (user || rcu_is_cpu_rrupt_from_idle()) {
 

kernel/rcu/update.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Read-Copy Update mechanism for mutual exclusion
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright IBM Corporation, 2001
  *
  * Authors: Dipankar Sarma <dipankar@in.ibm.com>
  *	    Manfred Spraul <manfred@colorfullife.com>
  *
- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
+ * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
  * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
  * Papers:
  * http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf

kernel/time/timer.c

@@ -1632,7 +1632,7 @@ void update_process_times(int user_tick)
 	/* Note: this timer irq context must be accounted for as well. */
 	account_process_tick(p, user_tick);
 	run_local_timers();
-	rcu_check_callbacks(user_tick);
+	rcu_sched_clock_irq(user_tick);
 #ifdef CONFIG_IRQ_WORK
 	if (in_irq())
 		irq_work_tick();

kernel/torture.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Common functions for in-kernel torture tests.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (C) IBM Corporation, 2014
  *
- * Author: Paul E. McKenney <paulmck@us.ibm.com>
+ * Author: Paul E. McKenney <paulmck@linux.ibm.com>
  *	Based on kernel/rcu/torture.c.
  */
 
@@ -53,7 +40,7 @@
 #include "rcu/rcu.h"
 
 MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
 
 static char *torture_type;
 static int verbose;
@@ -75,6 +62,7 @@ static DEFINE_MUTEX(fullstop_mutex);
 static struct task_struct *onoff_task;
 static long onoff_holdoff;
 static long onoff_interval;
+static torture_ofl_func *onoff_f;
 static long n_offline_attempts;
 static long n_offline_successes;
 static unsigned long sum_offline;
@@ -118,6 +106,8 @@ bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
 			pr_alert("%s" TORTURE_FLAG
 				 "torture_onoff task: offlined %d\n",
 				 torture_type, cpu);
+		if (onoff_f)
+			onoff_f();
 		(*n_offl_successes)++;
 		delta = jiffies - starttime;
 		*sum_offl += delta;
@@ -243,11 +233,12 @@ torture_onoff(void *arg)
 /*
  * Initiate online-offline handling.
  */
-int torture_onoff_init(long ooholdoff, long oointerval)
+int torture_onoff_init(long ooholdoff, long oointerval, torture_ofl_func *f)
 {
 #ifdef CONFIG_HOTPLUG_CPU
 	onoff_holdoff = ooholdoff;
 	onoff_interval = oointerval;
+	onoff_f = f;
 	if (onoff_interval <= 0)
 		return 0;
 	return torture_create_kthread(torture_onoff, NULL, onoff_task);

tools/testing/selftests/rcutorture/bin/mkinitrd.sh

@@ -40,17 +40,24 @@ mkdir $T
 cat > $T/init << '__EOF___'
 #!/bin/sh
 # Run in userspace a few milliseconds every second.  This helps to
-# exercise the NO_HZ_FULL portions of RCU.
+# exercise the NO_HZ_FULL portions of RCU.  The 192 instances of "a" was
+# empirically shown to give a nice multi-millisecond burst of user-mode
+# execution on a 2GHz CPU, as desired.  Modern CPUs will vary from a
+# couple of milliseconds up to perhaps 100 milliseconds, which is an
+# acceptable range.
+#
+# Why not calibrate an exact delay?  Because within this initrd, we
+# are restricted to Bourne-shell builtins, which as far as I know do not
+# provide any means of obtaining a fine-grained timestamp.
+
+a4="a a a a"
+a16="$a4 $a4 $a4 $a4"
+a64="$a16 $a16 $a16 $a16"
+a192="$a64 $a64 $a64"
 while :
 do
 	q=
-	for i in \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
+	for i in $a192
 	do
 		q="$q $i"
 	done
@@ -124,8 +131,8 @@ if echo -e "#if __x86_64__||__i386__||__i486__||__i586__||__i686__" \
    | grep -q '^yes'; then
 	# architecture supported by nolibc
         ${CROSS_COMPILE}gcc -fno-asynchronous-unwind-tables -fno-ident \
-		-nostdlib -include ../bin/nolibc.h -lgcc -s -static -Os \
-		-o init init.c
+		-nostdlib -include ../../../../include/nolibc/nolibc.h \
+		-lgcc -s -static -Os -o init init.c
 else
 	${CROSS_COMPILE}gcc -s -static -Os -o init init.c
 fi

virt/kvm/kvm_main.c

@@ -4083,7 +4083,7 @@ static int kvm_suspend(void)
 static void kvm_resume(void)
 {
 	if (kvm_usage_count) {
-		WARN_ON(raw_spin_is_locked(&kvm_count_lock));
+		lockdep_assert_held(&kvm_count_lock);
 		hardware_enable_nolock(NULL);
 	}
 }