locking, percpu counters: introduce separate lock classes

Impact: fix lockdep false positives

Classify percpu_counter instances similar to regular lock objects --
that is, per instantiation site.

The networking code has increased its use of percpu_counters, which
leads to false positives if they are treated as a single class.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 7 insertions, 17 deletions

diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index a866389..c7fe2e4 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -71,11 +71,11 @@ s64 __percpu_counter_sum(struct percpu_counter *fbc)
 }
 EXPORT_SYMBOL(__percpu_counter_sum);
 
-static struct lock_class_key percpu_counter_irqsafe;
-
-int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
+int __percpu_counter_init(struct percpu_counter *fbc, s64 amount,
+			  struct lock_class_key *key)
 {
 	spin_lock_init(&fbc->lock);
+	lockdep_set_class(&fbc->lock, key);
 	fbc->count = amount;
 	fbc->counters = alloc_percpu(s32);
 	if (!fbc->counters)
@@ -87,17 +87,7 @@ int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
 #endif
 	return 0;
 }
-EXPORT_SYMBOL(percpu_counter_init);
-
-int percpu_counter_init_irq(struct percpu_counter *fbc, s64 amount)
-{
-	int err;
-
-	err = percpu_counter_init(fbc, amount);
-	if (!err)
-		lockdep_set_class(&fbc->lock, &percpu_counter_irqsafe);
-	return err;
-}
+EXPORT_SYMBOL(__percpu_counter_init);
 
 void percpu_counter_destroy(struct percpu_counter *fbc)
 {
diff --git a/lib/proportions.c b/lib/proportions.c
index 4f387a6..7367f2b 100644
--- a/lib/proportions.c
+++ b/lib/proportions.c
@@ -83,11 +83,11 @@ int prop_descriptor_init(struct prop_descriptor *pd, int shift)
 	pd->index = 0;
 	pd->pg[0].shift = shift;
 	mutex_init(&pd->mutex);
-	err = percpu_counter_init_irq(&pd->pg[0].events, 0);
+	err = percpu_counter_init(&pd->pg[0].events, 0);
 	if (err)
 		goto out;
 
-	err = percpu_counter_init_irq(&pd->pg[1].events, 0);
+	err = percpu_counter_init(&pd->pg[1].events, 0);
 	if (err)
 		percpu_counter_destroy(&pd->pg[0].events);
 
@@ -191,7 +191,7 @@ int prop_local_init_percpu(struct prop_local_percpu *pl)
 	spin_lock_init(&pl->lock);
 	pl->shift = 0;
 	pl->period = 0;
-	return percpu_counter_init_irq(&pl->events, 0);
+	return percpu_counter_init(&pl->events, 0);
 }
 
 void prop_local_destroy_percpu(struct prop_local_percpu *pl)