linux-kernel - [tip:core/locking] lglock: Update lockdep annotations to report recursive local locks

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Message-ID: <tip-c4be9cb4f19cbd534a6c4c334cd48d8bb483e17a@git.kernel.org>
Date:	Fri, 12 Jul 2013 06:29:29 -0700
From:	tip-bot for Michel Lespinasse <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	rusty@...tcorp.com.au, peterz@...radead.org,
	srivatsa.bhat@...ux.vnet.ibm.com, akpm@...ux-foundation.org,
	rostedt@...dmis.org, paulmck@...ibm.com, ak@...ux.intel.com,
	tglx@...utronix.de, oleg@...hat.com, walken@...gle.com,
	laijs@...fujitsu.com
Subject: [tip:core/locking] lglock:
  Update lockdep annotations to report recursive local locks

Commit-ID:  c4be9cb4f19cbd534a6c4c334cd48d8bb483e17a
Gitweb:     http://git.kernel.org/tip/c4be9cb4f19cbd534a6c4c334cd48d8bb483e17a
Author:     Michel Lespinasse <walken@...gle.com>
AuthorDate: Mon, 8 Jul 2013 14:23:51 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 12 Jul 2013 13:51:19 +0200

lglock: Update lockdep annotations to report recursive local locks

Oleg Nesterov recently noticed that the lockdep annotations in lglock.c
are not sufficient to detect some obvious deadlocks, such as
lg_local_lock(LOCK) + lg_local_lock(LOCK) or spin_lock(X) +
lg_local_lock(Y) vs lg_local_lock(Y) + spin_lock(X).

Both issues are easily fixed by indicating to lockdep that lglock's local
locks are not recursive.  We shouldn't use the rwlock acquire/release
functions here, as lglock doesn't share the same semantics.  Instead we
can base our lockdep annotations on the lock_acquire_shared (for local
lglock) and lock_acquire_exclusive (for global lglock) helpers.

I am not proposing new lglock specific helpers as I don't see the point of
the existing second level of helpers :)

Noticed-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Michel Lespinasse <walken@...gle.com>
Cc: Lai Jiangshan <laijs@...fujitsu.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: "Paul E. McKenney" <paulmck@...ibm.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/20130708212352.1769031C15E@corp2gmr1-1.hot.corp.google.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/lglock.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/lglock.c b/kernel/lglock.c
index 6535a66..86ae2ae 100644
--- a/kernel/lglock.c
+++ b/kernel/lglock.c
@@ -21,7 +21,7 @@ void lg_local_lock(struct lglock *lg)
 	arch_spinlock_t *lock;
 
 	preempt_disable();
-	rwlock_acquire_read(&lg->lock_dep_map, 0, 0, _RET_IP_);
+	lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
 	lock = this_cpu_ptr(lg->lock);
 	arch_spin_lock(lock);
 }
@@ -31,7 +31,7 @@ void lg_local_unlock(struct lglock *lg)
 {
 	arch_spinlock_t *lock;
 
-	rwlock_release(&lg->lock_dep_map, 1, _RET_IP_);
+	lock_release(&lg->lock_dep_map, 1, _RET_IP_);
 	lock = this_cpu_ptr(lg->lock);
 	arch_spin_unlock(lock);
 	preempt_enable();
@@ -43,7 +43,7 @@ void lg_local_lock_cpu(struct lglock *lg, int cpu)
 	arch_spinlock_t *lock;
 
 	preempt_disable();
-	rwlock_acquire_read(&lg->lock_dep_map, 0, 0, _RET_IP_);
+	lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
 	lock = per_cpu_ptr(lg->lock, cpu);
 	arch_spin_lock(lock);
 }
@@ -53,7 +53,7 @@ void lg_local_unlock_cpu(struct lglock *lg, int cpu)
 {
 	arch_spinlock_t *lock;
 
-	rwlock_release(&lg->lock_dep_map, 1, _RET_IP_);
+	lock_release(&lg->lock_dep_map, 1, _RET_IP_);
 	lock = per_cpu_ptr(lg->lock, cpu);
 	arch_spin_unlock(lock);
 	preempt_enable();
@@ -65,7 +65,7 @@ void lg_global_lock(struct lglock *lg)
 	int i;
 
 	preempt_disable();
-	rwlock_acquire(&lg->lock_dep_map, 0, 0, _RET_IP_);
+	lock_acquire_exclusive(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
 	for_each_possible_cpu(i) {
 		arch_spinlock_t *lock;
 		lock = per_cpu_ptr(lg->lock, i);
@@ -78,7 +78,7 @@ void lg_global_unlock(struct lglock *lg)
 {
 	int i;
 
-	rwlock_release(&lg->lock_dep_map, 1, _RET_IP_);
+	lock_release(&lg->lock_dep_map, 1, _RET_IP_);
 	for_each_possible_cpu(i) {
 		arch_spinlock_t *lock;
 		lock = per_cpu_ptr(lg->lock, i);
--
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