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 a8663890a88c..c7fe2e4e8ed1 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 4f387a643d72..7367f2b727d0 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)