percpu_counter: change return value and add comments

The percpu_counter_*_positive() API in UP case doesn't check if return value is positive. Add comments to explain why we don't. Also if count < 0, returns 0 instead of 1 for *read_positive(). [[email protected]: tweak comment] Signed-off-by: Shaohua Li <[email protected]> Acked-by: Eric Dumazet <[email protected]> Cc: Tejun Heo <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
goeke · May 25, 2011 · c84598b · c84598b
1 parent 3c8f370
commit c84598b
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
@@ -75,7 +75,7 @@ static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
 	barrier();		/* Prevent reloads of fbc->count */
 	if (ret >= 0)
 		return ret;
-	return 1;
+	return 0;
 }
 
 static inline int percpu_counter_initialized(struct percpu_counter *fbc)
@@ -133,6 +133,10 @@ static inline s64 percpu_counter_read(struct percpu_counter *fbc)
 	return fbc->count;
 }
 
+/*
+ * percpu_counter is intended to track positive numbers. In the UP case the
+ * number should never be negative.
+ */
 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
 {
 	return fbc->count;