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Subject[PATCH 0.5/3] percpu_counter: make percpu_counters_lock irq-safe
percpu_counter is scheduled to grow @gfp support to allow atomic
initialization. This patch makes percpu_counters_lock irq-safe so
that it can be safely used from atomic contexts.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
lib/percpu_counter.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -115,6 +115,8 @@ EXPORT_SYMBOL(__percpu_counter_sum);
int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp,
struct lock_class_key *key)
{
+ unsigned long flags __maybe_unused;
+
raw_spin_lock_init(&fbc->lock);
lockdep_set_class(&fbc->lock, key);
fbc->count = amount;
@@ -126,9 +128,9 @@ int __percpu_counter_init(struct percpu_

#ifdef CONFIG_HOTPLUG_CPU
INIT_LIST_HEAD(&fbc->list);
- spin_lock(&percpu_counters_lock);
+ spin_lock_irqsave(&percpu_counters_lock, flags);
list_add(&fbc->list, &percpu_counters);
- spin_unlock(&percpu_counters_lock);
+ spin_unlock_irqrestore(&percpu_counters_lock, flags);
#endif
return 0;
}
@@ -136,15 +138,17 @@ EXPORT_SYMBOL(__percpu_counter_init);

void percpu_counter_destroy(struct percpu_counter *fbc)
{
+ unsigned long flags __maybe_unused;
+
if (!fbc->counters)
return;

debug_percpu_counter_deactivate(fbc);

#ifdef CONFIG_HOTPLUG_CPU
- spin_lock(&percpu_counters_lock);
+ spin_lock_irqsave(&percpu_counters_lock, flags);
list_del(&fbc->list);
- spin_unlock(&percpu_counters_lock);
+ spin_unlock_irqrestore(&percpu_counters_lock, flags);
#endif
free_percpu(fbc->counters);
fbc->counters = NULL;
@@ -173,7 +177,7 @@ static int percpu_counter_hotcpu_callbac
return NOTIFY_OK;

cpu = (unsigned long)hcpu;
- spin_lock(&percpu_counters_lock);
+ spin_lock_irq(&percpu_counters_lock);
list_for_each_entry(fbc, &percpu_counters, list) {
s32 *pcount;
unsigned long flags;
@@ -184,7 +188,7 @@ static int percpu_counter_hotcpu_callbac
*pcount = 0;
raw_spin_unlock_irqrestore(&fbc->lock, flags);
}
- spin_unlock(&percpu_counters_lock);
+ spin_unlock_irq(&percpu_counters_lock);
#endif
return NOTIFY_OK;
}

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