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Commit c4be9cb4 authored by Michel Lespinasse's avatar Michel Lespinasse Committed by Ingo Molnar
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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: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarMichel Lespinasse <walken@google.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130708212352.1769031C15E@corp2gmr1-1.hot.corp.google.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent a51805ef

kernel/lglock.c

+6 −6
Original line number Diff line number Diff line
@@ -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);