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RCU commits for 4.6

GIT PULL Paul E. McKenney 2 participants 4 messages Mar 7, 2016 – Mar 8, 2016 RCU

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Paul E. McKenney

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#0 lore raw

Hello, Ingo,

Note that this series conflicts with some commits in Thomas Gleixner's hotplug series and in Daniel Wagner's swait series, both of which are in -tip. I have suggested conflict-resolution commits for Daniel's commits (25f0d48a4299 "Merge commit 'abedf8e2419fb873d919dd74de2e84b510259339' into wagi.2016.03.01a") and for Thomas's commits (dc96aeda643f "Merge commit '27d50c7eeb0f' into wagi.2016.03.01a"), which you might find useful. These merge commits pass rcutorture testing, 0day robot testing, and -next testing.

The changes in this series include:

1. Documentation updates, including RCU data structure design-level

	documentation.

	https://lkml.org/lkml/2016/2/24/26

2. Miscellaneous fixes.

	https://lkml.org/lkml/2016/2/24/34

3. Torture-test updates.

	https://lkml.org/lkml/2016/2/24/50

As noted earlier, all of these changes have been subjected to 0day Test robot and -next testing, and are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git for-mingo

for you to fetch changes up to 2863b4e3dd92a9d697dd66b219710e478e0a4531:

Merge branches 'doc.2015.02.23a', 'fixes.2015.02.23a' and 'torture.2015.02.23a' into HEAD (2016-02-23 20:05:19 -0800)

----------------------------------------------------------------
Boqun Feng (3):
sparse: Add __private to privatize members of structs
RCU: Privatize rcu_node::lock
irq: Privatize irq_common_data::state_use_accessors

Chen Gang (1):
rcu: Remove useless rcu_data_p when !PREEMPT_RCU

Paul E. McKenney (25):
rcutorture: Add checks for rcutorture writer starvation
rcutorture: Don't keep empty console.log.diags files
rcutorture: Check for self-detected stalls
documentation: Add real-time requirements from CPU-bound workloads
documentation: Fix control dependency and identical stores
documentation: Fix memory-barriers.txt section references
documentation: Add synchronize_rcu_mult() to the requirements
documentation: Remove obsolete reference to RCU-protected indexes
documentation: Subsequent writes ordered by rcu_dereference()
documentation: Distinguish between local and global transitivity
documentation: Add alternative release-acquire outcome
documentation: Add documentation for RCU's major data structures
documentation: Explain why rcu_read_lock() needs no barrier()
documentation: Transitivity is not cumulativity
documentation: Document illegality of call_rcu() from offline CPUs
documentation: Explain how RCU's combining tree fights contention
rcu: Assign false instead of 0 for ->core_needs_qs
rcu: Update rcu_report_qs_rsp() comment
rcu: Stop treating in-kernel CPU-bound workloads as errors
rcu: Set rdp->gpwrap when CPU is idle
rcutorture: Correct no-expedite console messages
rcu: Document unique-name limitation for DEFINE_STATIC_SRCU()
rcu: Catch up rcu_report_qs_rdp() comment with reality
rcu: Export rcu_gp_is_normal()
Merge branches 'doc.2015.02.23a', 'fixes.2015.02.23a' and 'torture.2015.02.23a' into HEAD

Paul Gortmaker (1):
rcu: Make rcu/tiny_plugin.h explicitly non-modular

SeongJae Park (1):
documentation: Clarify compiler store-fusion example

Yang Shi (1):
rcu: Remove rcu_user_hooks_switch

 .../Design/Data-Structures/BigTreeClassicRCU.svg   |  474 +++++++
 .../Design/Data-Structures/BigTreeClassicRCUBH.svg |  499 +++++++
 .../Data-Structures/BigTreeClassicRCUBHdyntick.svg |  695 ++++++++++
 .../Data-Structures/BigTreePreemptRCUBHdyntick.svg |  741 +++++++++++
 .../BigTreePreemptRCUBHdyntickCB.svg               |  858 ++++++++++++
 .../Design/Data-Structures/Data-Structures.html    | 1395 ++++++++++++++++++++
 .../Design/Data-Structures/Data-Structures.htmlx   | 1295 ++++++++++++++++++
 .../Design/Data-Structures/HugeTreeClassicRCU.svg  |  939 +++++++++++++
 .../RCU/Design/Data-Structures/TreeLevel.svg       |  828 ++++++++++++
 .../RCU/Design/Data-Structures/TreeMapping.svg     |  305 +++++
 .../Design/Data-Structures/TreeMappingLevel.svg    |  380 ++++++
 .../RCU/Design/Data-Structures/blkd_task.svg       |  843 ++++++++++++
 .../RCU/Design/Data-Structures/nxtlist.svg         |  396 ++++++
 .../RCU/Design/Requirements/Requirements.html      |  225 +++-
 .../RCU/Design/Requirements/Requirements.htmlx     |  121 +-
 Documentation/memory-barriers.txt                  |  141 +-
 include/linux/compiler.h                           |   12 +-
 include/linux/irq.h                                |    6 +-
 include/linux/rcupdate.h                           |    2 -
 include/linux/srcu.h                               |   19 +-
 kernel/irq/internals.h                             |    4 +
 kernel/rcu/rcutorture.c                            |   14 +-
 kernel/rcu/tiny_plugin.h                           |   15 +-
 kernel/rcu/tree.c                                  |  143 +-
 kernel/rcu/tree.h                                  |   42 +-
 kernel/rcu/tree_plugin.h                           |   27 +-
 kernel/rcu/update.c                                |    1 +
 scripts/checkpatch.pl                              |    3 +-
 .../selftests/rcutorture/bin/parse-console.sh      |    6 +-
 29 files changed, 10233 insertions(+), 196 deletions(-)
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreeClassicRCU.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreeClassicRCUBH.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreeClassicRCUBHdyntick.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreePreemptRCUBHdyntick.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreePreemptRCUBHdyntickCB.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/Data-Structures.html
 create mode 100644 Documentation/RCU/Design/Data-Structures/Data-Structures.htmlx
 create mode 100644 Documentation/RCU/Design/Data-Structures/HugeTreeClassicRCU.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/TreeLevel.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/TreeMapping.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/TreeMappingLevel.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/blkd_task.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/nxtlist.svg
#1 lore raw
Quoted 115 lines · Paul E. McKenney

Hello, Ingo,

Note that this series conflicts with some commits in Thomas Gleixner's hotplug series and in Daniel Wagner's swait series, both of which are in -tip. I have suggested conflict-resolution commits for Daniel's commits (25f0d48a4299 "Merge commit 'abedf8e2419fb873d919dd74de2e84b510259339' into wagi.2016.03.01a") and for Thomas's commits (dc96aeda643f "Merge commit '27d50c7eeb0f' into wagi.2016.03.01a"), which you might find useful. These merge commits pass rcutorture testing, 0day robot testing, and -next testing.

The changes in this series include:

1. Documentation updates, including RCU data structure design-level

	documentation.

	https://lkml.org/lkml/2016/2/24/26

2. Miscellaneous fixes.

	https://lkml.org/lkml/2016/2/24/34

3. Torture-test updates.

	https://lkml.org/lkml/2016/2/24/50

As noted earlier, all of these changes have been subjected to 0day Test robot and -next testing, and are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git for-mingo

for you to fetch changes up to 2863b4e3dd92a9d697dd66b219710e478e0a4531:

Merge branches 'doc.2015.02.23a', 'fixes.2015.02.23a' and 'torture.2015.02.23a' into HEAD (2016-02-23 20:05:19 -0800)

----------------------------------------------------------------
Boqun Feng (3):
sparse: Add __private to privatize members of structs
RCU: Privatize rcu_node::lock
irq: Privatize irq_common_data::state_use_accessors

Chen Gang (1):
rcu: Remove useless rcu_data_p when !PREEMPT_RCU

Paul E. McKenney (25):
rcutorture: Add checks for rcutorture writer starvation
rcutorture: Don't keep empty console.log.diags files
rcutorture: Check for self-detected stalls
documentation: Add real-time requirements from CPU-bound workloads
documentation: Fix control dependency and identical stores
documentation: Fix memory-barriers.txt section references
documentation: Add synchronize_rcu_mult() to the requirements
documentation: Remove obsolete reference to RCU-protected indexes
documentation: Subsequent writes ordered by rcu_dereference()
documentation: Distinguish between local and global transitivity
documentation: Add alternative release-acquire outcome
documentation: Add documentation for RCU's major data structures
documentation: Explain why rcu_read_lock() needs no barrier()
documentation: Transitivity is not cumulativity
documentation: Document illegality of call_rcu() from offline CPUs
documentation: Explain how RCU's combining tree fights contention
rcu: Assign false instead of 0 for ->core_needs_qs
rcu: Update rcu_report_qs_rsp() comment
rcu: Stop treating in-kernel CPU-bound workloads as errors
rcu: Set rdp->gpwrap when CPU is idle
rcutorture: Correct no-expedite console messages
rcu: Document unique-name limitation for DEFINE_STATIC_SRCU()
rcu: Catch up rcu_report_qs_rdp() comment with reality
rcu: Export rcu_gp_is_normal()
Merge branches 'doc.2015.02.23a', 'fixes.2015.02.23a' and 'torture.2015.02.23a' into HEAD

Paul Gortmaker (1):
rcu: Make rcu/tiny_plugin.h explicitly non-modular

SeongJae Park (1):
documentation: Clarify compiler store-fusion example

Yang Shi (1):
rcu: Remove rcu_user_hooks_switch

 .../Design/Data-Structures/BigTreeClassicRCU.svg   |  474 +++++++
 .../Design/Data-Structures/BigTreeClassicRCUBH.svg |  499 +++++++
 .../Data-Structures/BigTreeClassicRCUBHdyntick.svg |  695 ++++++++++
 .../Data-Structures/BigTreePreemptRCUBHdyntick.svg |  741 +++++++++++
 .../BigTreePreemptRCUBHdyntickCB.svg               |  858 ++++++++++++
 .../Design/Data-Structures/Data-Structures.html    | 1395 ++++++++++++++++++++
 .../Design/Data-Structures/Data-Structures.htmlx   | 1295 ++++++++++++++++++
 .../Design/Data-Structures/HugeTreeClassicRCU.svg  |  939 +++++++++++++
 .../RCU/Design/Data-Structures/TreeLevel.svg       |  828 ++++++++++++
 .../RCU/Design/Data-Structures/TreeMapping.svg     |  305 +++++
 .../Design/Data-Structures/TreeMappingLevel.svg    |  380 ++++++
 .../RCU/Design/Data-Structures/blkd_task.svg       |  843 ++++++++++++
 .../RCU/Design/Data-Structures/nxtlist.svg         |  396 ++++++
 .../RCU/Design/Requirements/Requirements.html      |  225 +++-
 .../RCU/Design/Requirements/Requirements.htmlx     |  121 +-
 Documentation/memory-barriers.txt                  |  141 +-
 include/linux/compiler.h                           |   12 +-
 include/linux/irq.h                                |    6 +-
 include/linux/rcupdate.h                           |    2 -
 include/linux/srcu.h                               |   19 +-
 kernel/irq/internals.h                             |    4 +
 kernel/rcu/rcutorture.c                            |   14 +-
 kernel/rcu/tiny_plugin.h                           |   15 +-
 kernel/rcu/tree.c                                  |  143 +-
 kernel/rcu/tree.h                                  |   42 +-
 kernel/rcu/tree_plugin.h                           |   27 +-
 kernel/rcu/update.c                                |    1 +
 scripts/checkpatch.pl                              |    3 +-
 .../selftests/rcutorture/bin/parse-console.sh      |    6 +-
 29 files changed, 10233 insertions(+), 196 deletions(-)
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreeClassicRCU.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreeClassicRCUBH.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreeClassicRCUBHdyntick.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreePreemptRCUBHdyntick.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreePreemptRCUBHdyntickCB.svg
Quoted 8 lines
 create mode 100644 Documentation/RCU/Design/Data-Structures/Data-Structures.html
 create mode 100644 Documentation/RCU/Design/Data-Structures/Data-Structures.htmlx
 create mode 100644 Documentation/RCU/Design/Data-Structures/HugeTreeClassicRCU.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/TreeLevel.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/TreeMapping.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/TreeMappingLevel.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/blkd_task.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/nxtlist.svg

Pulled, thanks a lot Paul!

So I've done the conflict resolutions with tmp:smp/hotplug and tip:sched/core myself, and came up with a mostly identical resolution, except this difference with your resolution in wagi.2016.03.01a:

kernel/rcu/tree.c +1 -1
@@ -2046,8 +2046,8 @@ static void rcu_gp_cleanup(struct rcu_st
 		/* smp_mb() provided by prior unlock-lock pair. */
 		nocb += rcu_future_gp_cleanup(rsp, rnp);
 		sq = rcu_nocb_gp_get(rnp);
-		raw_spin_unlock_irq_rcu_node(rnp);
 		rcu_nocb_gp_cleanup(sq);
+		raw_spin_unlock_irq_rcu_node(rnp);
 		cond_resched_rcu_qs();
 		WRITE_ONCE(rsp->gp_activity, jiffies);
 		rcu_gp_slow(rsp, gp_cleanup_delay);

but your resolution is better, rcu_nocb_gp_cleanup() can (and should) be done outside of the rcu_node lock.

So we have the same resolution now, which is good! ;-)

Thanks,

Ingo

author
#2 lore raw
Quoted 146 lines · Ingo Molnar
Quoted 115 lines · Paul E. McKenney

Hello, Ingo,

Note that this series conflicts with some commits in Thomas Gleixner's hotplug series and in Daniel Wagner's swait series, both of which are in -tip. I have suggested conflict-resolution commits for Daniel's commits (25f0d48a4299 "Merge commit 'abedf8e2419fb873d919dd74de2e84b510259339' into wagi.2016.03.01a") and for Thomas's commits (dc96aeda643f "Merge commit '27d50c7eeb0f' into wagi.2016.03.01a"), which you might find useful. These merge commits pass rcutorture testing, 0day robot testing, and -next testing.

The changes in this series include:

1. Documentation updates, including RCU data structure design-level

	documentation.

	https://lkml.org/lkml/2016/2/24/26

2. Miscellaneous fixes.

	https://lkml.org/lkml/2016/2/24/34

3. Torture-test updates.

	https://lkml.org/lkml/2016/2/24/50

As noted earlier, all of these changes have been subjected to 0day Test robot and -next testing, and are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git for-mingo

for you to fetch changes up to 2863b4e3dd92a9d697dd66b219710e478e0a4531:

Merge branches 'doc.2015.02.23a', 'fixes.2015.02.23a' and 'torture.2015.02.23a' into HEAD (2016-02-23 20:05:19 -0800)

----------------------------------------------------------------
Boqun Feng (3):
sparse: Add __private to privatize members of structs
RCU: Privatize rcu_node::lock
irq: Privatize irq_common_data::state_use_accessors

Chen Gang (1):
rcu: Remove useless rcu_data_p when !PREEMPT_RCU

Paul E. McKenney (25):
rcutorture: Add checks for rcutorture writer starvation
rcutorture: Don't keep empty console.log.diags files
rcutorture: Check for self-detected stalls
documentation: Add real-time requirements from CPU-bound workloads
documentation: Fix control dependency and identical stores
documentation: Fix memory-barriers.txt section references
documentation: Add synchronize_rcu_mult() to the requirements
documentation: Remove obsolete reference to RCU-protected indexes
documentation: Subsequent writes ordered by rcu_dereference()
documentation: Distinguish between local and global transitivity
documentation: Add alternative release-acquire outcome
documentation: Add documentation for RCU's major data structures
documentation: Explain why rcu_read_lock() needs no barrier()
documentation: Transitivity is not cumulativity
documentation: Document illegality of call_rcu() from offline CPUs
documentation: Explain how RCU's combining tree fights contention
rcu: Assign false instead of 0 for ->core_needs_qs
rcu: Update rcu_report_qs_rsp() comment
rcu: Stop treating in-kernel CPU-bound workloads as errors
rcu: Set rdp->gpwrap when CPU is idle
rcutorture: Correct no-expedite console messages
rcu: Document unique-name limitation for DEFINE_STATIC_SRCU()
rcu: Catch up rcu_report_qs_rdp() comment with reality
rcu: Export rcu_gp_is_normal()
Merge branches 'doc.2015.02.23a', 'fixes.2015.02.23a' and 'torture.2015.02.23a' into HEAD

Paul Gortmaker (1):
rcu: Make rcu/tiny_plugin.h explicitly non-modular

SeongJae Park (1):
documentation: Clarify compiler store-fusion example

Yang Shi (1):
rcu: Remove rcu_user_hooks_switch

 .../Design/Data-Structures/BigTreeClassicRCU.svg   |  474 +++++++
 .../Design/Data-Structures/BigTreeClassicRCUBH.svg |  499 +++++++
 .../Data-Structures/BigTreeClassicRCUBHdyntick.svg |  695 ++++++++++
 .../Data-Structures/BigTreePreemptRCUBHdyntick.svg |  741 +++++++++++
 .../BigTreePreemptRCUBHdyntickCB.svg               |  858 ++++++++++++
 .../Design/Data-Structures/Data-Structures.html    | 1395 ++++++++++++++++++++
 .../Design/Data-Structures/Data-Structures.htmlx   | 1295 ++++++++++++++++++
 .../Design/Data-Structures/HugeTreeClassicRCU.svg  |  939 +++++++++++++
 .../RCU/Design/Data-Structures/TreeLevel.svg       |  828 ++++++++++++
 .../RCU/Design/Data-Structures/TreeMapping.svg     |  305 +++++
 .../Design/Data-Structures/TreeMappingLevel.svg    |  380 ++++++
 .../RCU/Design/Data-Structures/blkd_task.svg       |  843 ++++++++++++
 .../RCU/Design/Data-Structures/nxtlist.svg         |  396 ++++++
 .../RCU/Design/Requirements/Requirements.html      |  225 +++-
 .../RCU/Design/Requirements/Requirements.htmlx     |  121 +-
 Documentation/memory-barriers.txt                  |  141 +-
 include/linux/compiler.h                           |   12 +-
 include/linux/irq.h                                |    6 +-
 include/linux/rcupdate.h                           |    2 -
 include/linux/srcu.h                               |   19 +-
 kernel/irq/internals.h                             |    4 +
 kernel/rcu/rcutorture.c                            |   14 +-
 kernel/rcu/tiny_plugin.h                           |   15 +-
 kernel/rcu/tree.c                                  |  143 +-
 kernel/rcu/tree.h                                  |   42 +-
 kernel/rcu/tree_plugin.h                           |   27 +-
 kernel/rcu/update.c                                |    1 +
 scripts/checkpatch.pl                              |    3 +-
 .../selftests/rcutorture/bin/parse-console.sh      |    6 +-
 29 files changed, 10233 insertions(+), 196 deletions(-)
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreeClassicRCU.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreeClassicRCUBH.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreeClassicRCUBHdyntick.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreePreemptRCUBHdyntick.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/BigTreePreemptRCUBHdyntickCB.svg
Quoted 8 lines
 create mode 100644 Documentation/RCU/Design/Data-Structures/Data-Structures.html
 create mode 100644 Documentation/RCU/Design/Data-Structures/Data-Structures.htmlx
 create mode 100644 Documentation/RCU/Design/Data-Structures/HugeTreeClassicRCU.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/TreeLevel.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/TreeMapping.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/TreeMappingLevel.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/blkd_task.svg
 create mode 100644 Documentation/RCU/Design/Data-Structures/nxtlist.svg

Pulled, thanks a lot Paul!

So I've done the conflict resolutions with tmp:smp/hotplug and tip:sched/core myself, and came up with a mostly identical resolution, except this difference with your resolution in wagi.2016.03.01a:

kernel/rcu/tree.c +1 -1
@@ -2046,8 +2046,8 @@ static void rcu_gp_cleanup(struct rcu_st
 		/* smp_mb() provided by prior unlock-lock pair. */
 		nocb += rcu_future_gp_cleanup(rsp, rnp);
 		sq = rcu_nocb_gp_get(rnp);
-		raw_spin_unlock_irq_rcu_node(rnp);
 		rcu_nocb_gp_cleanup(sq);
+		raw_spin_unlock_irq_rcu_node(rnp);
 		cond_resched_rcu_qs();
 		WRITE_ONCE(rsp->gp_activity, jiffies);
 		rcu_gp_slow(rsp, gp_cleanup_delay);
Quoted 4 lines

but your resolution is better, rcu_nocb_gp_cleanup() can (and should) be done outside of the rcu_node lock.

So we have the same resolution now, which is good! ;-)

Glad we were close!

Just for purposes of satisfying curiosity, I am running rcutorture on your version. ;-)

Thanx, Paul

author
#3 lore raw
Quoted 2 lines · Paul E. McKenney
Quoted 1 line · Ingo Molnar

* Paul E. McKenney <[email protected]> wrote:

[ . . . ]

Quoted 22 lines
Quoted 22 lines

Pulled, thanks a lot Paul!

So I've done the conflict resolutions with tmp:smp/hotplug and tip:sched/core myself, and came up with a mostly identical resolution, except this difference with your resolution in wagi.2016.03.01a:

kernel/rcu/tree.c +1 -1
@@ -2046,8 +2046,8 @@ static void rcu_gp_cleanup(struct rcu_st
 		/* smp_mb() provided by prior unlock-lock pair. */
 		nocb += rcu_future_gp_cleanup(rsp, rnp);
 		sq = rcu_nocb_gp_get(rnp);
-		raw_spin_unlock_irq_rcu_node(rnp);
 		rcu_nocb_gp_cleanup(sq);
+		raw_spin_unlock_irq_rcu_node(rnp);
 		cond_resched_rcu_qs();
 		WRITE_ONCE(rsp->gp_activity, jiffies);
 		rcu_gp_slow(rsp, gp_cleanup_delay);

but your resolution is better, rcu_nocb_gp_cleanup() can (and should) be done outside of the rcu_node lock.

Quoted 6 lines
Quoted 1 line

So we have the same resolution now, which is good! ;-)

Glad we were close!

Just for purposes of satisfying curiosity, I am running rcutorture on your version. ;-)

And for whatever it is worth, in one of the sixteen rcutorture scenarios lockdep complained as shown below.

On the other hand, your version quite possibly makes a lost-wakeup bug happen more frequently. If my current quest to create a torture test specific to this bug fails, I will revisit your patch. So despite the lockdep splat, it is quite possible that I will be thanking you for it at some point. ;-)

Thanx, Paul

------------------------------------------------------------------------

[    0.546319] =================================
[    0.547000] [ INFO: inconsistent lock state ]
[    0.547000] 4.5.0-rc6+ #1 Not tainted
[    0.547000] ---------------------------------
[    0.547000] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
[    0.547000] swapper/0/0 [HC0[0]:SC1[1]:HE0:SE0] takes:
[    0.547000]  (rcu_node_2){+.?...}, at: [<ffffffff810bd9e4>] rcu_process_callbacks+0xf4/0x860
[    0.547000] {SOFTIRQ-ON-W} state was registered at:
[    0.547000]   [<ffffffff810a22c6>] mark_held_locks+0x66/0x90
[    0.547000]   [<ffffffff810a23e4>] trace_hardirqs_on_caller+0xf4/0x1c0
[    0.547000]   [<ffffffff810a24bd>] trace_hardirqs_on+0xd/0x10
[    0.547000]   [<ffffffff8197e987>] _raw_spin_unlock_irq+0x27/0x50
[    0.547000]   [<ffffffff8109cd36>] swake_up_all+0xb6/0xd0
[    0.547000]   [<ffffffff810bd375>] rcu_gp_kthread+0x835/0xaf0
[    0.547000]   [<ffffffff8107b04f>] kthread+0xdf/0x100
[    0.547000]   [<ffffffff8197f4ff>] ret_from_fork+0x3f/0x70
[    0.547000] irq event stamp: 34721
[    0.547000] hardirqs last  enabled at (34720): [<ffffffff810baf33>] note_gp_changes+0x43/0xa0
[    0.547000] hardirqs last disabled at (34721): [<ffffffff8197e767>] _raw_spin_lock_irqsave+0x17/0x60
[    0.547000] softirqs last  enabled at (34712): [<ffffffff8105d84c>] _local_bh_enable+0x1c/0x50
[    0.547000] softirqs last disabled at (34713): [<ffffffff8105edb5>] irq_exit+0xa5/0xb0
[    0.547000] 
[    0.547000] other info that might help us debug this:
[    0.547000]  Possible unsafe locking scenario:
[    0.547000] 
[    0.547000]        CPU0
[    0.547000]        ----
[    0.547000]   lock(rcu_node_2);
[    0.547000]   <Interrupt>
[    0.547000]     lock(rcu_node_2);
[    0.547000] 
[    0.547000]  *** DEADLOCK ***
[    0.547000] 
[    0.547000] no locks held by swapper/0/0.
[    0.547000] 
[    0.547000] stack backtrace:
[    0.547000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.5.0-rc6+ #1
[    0.547000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[    0.547000]  0000000000000000 ffff88001fc03cc0 ffffffff813730ee ffffffff81e1d500
[    0.547000]  ffffffff83874a20 ffff88001fc03d10 ffffffff8113cf77 0000000000000001
[    0.547000]  ffffffff00000000 ffff880000000000 0000000000000006 ffffffff81e1d500
[    0.547000] Call Trace:
[    0.547000]  <IRQ>  [<ffffffff813730ee>] dump_stack+0x67/0x99
[    0.547000]  [<ffffffff8113cf77>] print_usage_bug+0x1f2/0x203
[    0.547000]  [<ffffffff810a1840>] ? check_usage_backwards+0x120/0x120
[    0.547000]  [<ffffffff810a21d2>] mark_lock+0x212/0x2a0
[    0.547000]  [<ffffffff810a2b17>] __lock_acquire+0x397/0x1b50
[    0.547000]  [<ffffffff8108ebce>] ? update_blocked_averages+0x3e/0x4a0
[    0.547000]  [<ffffffff8197e945>] ? _raw_spin_unlock_irqrestore+0x55/0x70
[    0.547000]  [<ffffffff810a2394>] ? trace_hardirqs_on_caller+0xa4/0x1c0
[    0.547000]  [<ffffffff8109625a>] ? rebalance_domains+0x10a/0x3b0
[    0.547000]  [<ffffffff810a4ae5>] lock_acquire+0xc5/0x1e0
[    0.547000]  [<ffffffff810bd9e4>] ? rcu_process_callbacks+0xf4/0x860
[    0.547000]  [<ffffffff8197e791>] _raw_spin_lock_irqsave+0x41/0x60
[    0.547000]  [<ffffffff810bd9e4>] ? rcu_process_callbacks+0xf4/0x860
[    0.547000]  [<ffffffff810bd9e4>] rcu_process_callbacks+0xf4/0x860
[    0.547000]  [<ffffffff810966c8>] ? run_rebalance_domains+0x1c8/0x1f0
[    0.547000]  [<ffffffff8105e7b9>] __do_softirq+0x139/0x490
[    0.547000]  [<ffffffff8105edb5>] irq_exit+0xa5/0xb0
[    0.547000]  [<ffffffff8103d2cd>] smp_apic_timer_interrupt+0x3d/0x50
[    0.547000]  [<ffffffff8197ff29>] apic_timer_interrupt+0x89/0x90
[    0.547000]  <EOI>  [<ffffffff8100e738>] ? default_idle+0x18/0x1a0
[    0.547000]  [<ffffffff8100e736>] ? default_idle+0x16/0x1a0
[    0.547000]  [<ffffffff8100f11a>] arch_cpu_idle+0xa/0x10
[    0.547000]  [<ffffffff8109d035>] default_idle_call+0x25/0x40
[    0.547000]  [<ffffffff8109d2e8>] cpu_startup_entry+0x298/0x3c0
[    0.547000]  [<ffffffff8197768f>] rest_init+0x12f/0x140
[    0.547000]  [<ffffffff81977560>] ? csum_partial_copy_generic+0x170/0x170
[    0.547000]  [<ffffffff81f6ffd5>] start_kernel+0x435/0x442
[    0.547000]  [<ffffffff81f6f98e>] ? set_init_arg+0x55/0x55
[    0.547000]  [<ffffffff81f6f5ad>] x86_64_start_reservations+0x2a/0x2c
[    0.547000]  [<ffffffff81f6f699>] x86_64_start_kernel+0xea/0xed