From ea319518ba3de282c13ae1cf4bf2215c5e03e67e Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 26 Dec 2008 15:08:55 +0100 Subject: [PATCH] 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 Signed-off-by: Ingo Molnar --- include/linux/percpu_counter.h | 14 ++++++++++---- lib/percpu_counter.c | 18 ++++-------------- lib/proportions.c | 6 +++--- mm/backing-dev.c | 2 +- 4 files changed, 18 insertions(+), 22 deletions(-) diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h index 9007ccd..96bdde3 100644 --- a/include/linux/percpu_counter.h +++ b/include/linux/percpu_counter.h @@ -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) { } 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) diff --git a/mm/backing-dev.c b/mm/backing-dev.c index f2e574d..f3b1258 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -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; } -- 2.7.4