lib: percpu_counter_set

Provide a method to set a percpu counter to a specified value.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 20 insertions, 0 deletions

diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
index e8fa2da13ba6..2da92e8ce3dd 100644
--- a/include/linux/percpu_counter.h
+++ b/include/linux/percpu_counter.h
@@ -32,6 +32,7 @@ struct percpu_counter {
 
 void percpu_counter_init(struct percpu_counter *fbc, s64 amount);
 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);
 s64 percpu_counter_sum(struct percpu_counter *fbc);
 
@@ -75,6 +76,11 @@ static inline void percpu_counter_destroy(struct percpu_counter *fbc)
 {
 }
 
+static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
+{
+        fbc->count = amount;
+}
+
 #define __percpu_counter_add(fbc, amount, batch) \
         percpu_counter_add(fbc, amount)
 
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index f7ac68c4c375..c9708db9b8d3 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -14,6 +14,20 @@ static LIST_HEAD(percpu_counters);
 static DEFINE_MUTEX(percpu_counters_lock);
 #endif
 
+void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
+{
+        int cpu;
+
+        spin_lock(&fbc->lock);
+        for_each_possible_cpu(cpu) {
+                s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
+                *pcount = 0;
+        }
+        fbc->count = amount;
+        spin_unlock(&fbc->lock);
+}
+EXPORT_SYMBOL(percpu_counter_set);
+
 void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
 {
         s64 count;