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>

diff --git a/kernel/lglock.c b/kernel/lglock.c
index 6535a66..86ae2ae 100644 (file)
--- 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);