linux/kernel/lglock.c
Michel Lespinasse c4be9cb4f1 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@redhat.com>
Signed-off-by: Michel 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130708212352.1769031C15E@corp2gmr1-1.hot.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-07-12 13:51:19 +02:00

90 lines
1.9 KiB
C

/* See include/linux/lglock.h for description */
#include <linux/module.h>
#include <linux/lglock.h>
#include <linux/cpu.h>
#include <linux/string.h>
/*
* Note there is no uninit, so lglocks cannot be defined in
* modules (but it's fine to use them from there)
* Could be added though, just undo lg_lock_init
*/
void lg_lock_init(struct lglock *lg, char *name)
{
LOCKDEP_INIT_MAP(&lg->lock_dep_map, name, &lg->lock_key, 0);
}
EXPORT_SYMBOL(lg_lock_init);
void lg_local_lock(struct lglock *lg)
{
arch_spinlock_t *lock;
preempt_disable();
lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
lock = this_cpu_ptr(lg->lock);
arch_spin_lock(lock);
}
EXPORT_SYMBOL(lg_local_lock);
void lg_local_unlock(struct lglock *lg)
{
arch_spinlock_t *lock;
lock_release(&lg->lock_dep_map, 1, _RET_IP_);
lock = this_cpu_ptr(lg->lock);
arch_spin_unlock(lock);
preempt_enable();
}
EXPORT_SYMBOL(lg_local_unlock);
void lg_local_lock_cpu(struct lglock *lg, int cpu)
{
arch_spinlock_t *lock;
preempt_disable();
lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
lock = per_cpu_ptr(lg->lock, cpu);
arch_spin_lock(lock);
}
EXPORT_SYMBOL(lg_local_lock_cpu);
void lg_local_unlock_cpu(struct lglock *lg, int cpu)
{
arch_spinlock_t *lock;
lock_release(&lg->lock_dep_map, 1, _RET_IP_);
lock = per_cpu_ptr(lg->lock, cpu);
arch_spin_unlock(lock);
preempt_enable();
}
EXPORT_SYMBOL(lg_local_unlock_cpu);
void lg_global_lock(struct lglock *lg)
{
int i;
preempt_disable();
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);
arch_spin_lock(lock);
}
}
EXPORT_SYMBOL(lg_global_lock);
void lg_global_unlock(struct lglock *lg)
{
int i;
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);
arch_spin_unlock(lock);
}
preempt_enable();
}
EXPORT_SYMBOL(lg_global_unlock);