lib: percpu_count_sum()

Provide an accurate version of percpu_counter_read.

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>
diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index b0d80ea..3b0ed80 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -52,7 +52,7 @@
  * Add up all the per-cpu counts, return the result.  This is a more accurate
  * but much slower version of percpu_counter_read_positive()
  */
-s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
+s64 __percpu_counter_sum(struct percpu_counter *fbc)
 {
 	s64 ret;
 	int cpu;
@@ -64,9 +64,9 @@
 		ret += *pcount;
 	}
 	spin_unlock(&fbc->lock);
-	return ret < 0 ? 0 : ret;
+	return ret;
 }
-EXPORT_SYMBOL(percpu_counter_sum_positive);
+EXPORT_SYMBOL(__percpu_counter_sum);
 
 void percpu_counter_init(struct percpu_counter *fbc, s64 amount)
 {