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>

include/linux/percpu_counter.h

diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
index e8fa2da..2da92e8 100644
--- a/include/linux/percpu_counter.h
+++ b/include/linux/percpu_counter.h
@@ -32,6 +32,7 @@
 
 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_set(struct percpu_counter *fbc, s64 amount)
+{
+	fbc->count = amount;
+}
+
 #define __percpu_counter_add(fbc, amount, batch) \
 	percpu_counter_add(fbc, amount)
 

lib/percpu_counter.c

diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index f7ac68c..c9708db9 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -14,6 +14,20 @@
 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;