Commit ea319518 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 00ef9f73

include/linux/percpu_counter.h

+10 −4
Original line number Diff line number Diff line
@@ -30,8 +30,16 @@ struct percpu_counter { 
#define FBC_BATCH	(NR_CPUS*4)

#endif



int percpu_counter_init(struct percpu_counter *fbc, s64 amount);

int percpu_counter_init_irq(struct percpu_counter *fbc, s64 amount);

int __percpu_counter_init(struct percpu_counter *fbc, s64 amount,

			  struct lock_class_key *key);



#define percpu_counter_init(fbc, value)					\

	({								\

		static struct lock_class_key __key;			\

									\

		__percpu_counter_init(fbc, value, &__key);		\

	})



void percpu_counter_destroy(struct percpu_counter *fbc);

void percpu_counter_set(struct percpu_counter *fbc, s64 amount);

void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
@@ -85,8 +93,6 @@ static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount) 
	return 0;

}



#define percpu_counter_init_irq percpu_counter_init



static inline void percpu_counter_destroy(struct percpu_counter *fbc)

{

}

lib/percpu_counter.c

+4 −14
Original line number Diff line number Diff line
@@ -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)

{

lib/proportions.c

+3 −3
Original line number Diff line number Diff line
@@ -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)

mm/backing-dev.c

+1 −1
Original line number Diff line number Diff line
@@ -220,7 +220,7 @@ int bdi_init(struct backing_dev_info *bdi) 
	bdi->max_prop_frac = PROP_FRAC_BASE;



	for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {

		err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);

		err = percpu_counter_init(&bdi->bdi_stat[i], 0);

		if (err)

			goto err;

	}

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