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>

1 files changed, 10 insertions, 6 deletions

diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index 7dd33577b905..3fde78275cd1 100644
--- 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,
                           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_counter *fbc, s64 amount,
 
 #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_callback(struct notifier_block *nb,
                 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_callback(struct notifier_block *nb,
                 *pcount = 0;
                 raw_spin_unlock_irqrestore(&fbc->lock, flags);
         }
-        spin_unlock(&percpu_counters_lock);
+        spin_unlock_irq(&percpu_counters_lock);
 #endif
         return NOTIFY_OK;
 }