percpu_counter: change return value and add comments

Shaohua Li · torvalds · commit c84598bbfa75 · 2011-05-25T08:39:54.000-07:00
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 &lt;
0, returns 0 instead of 1 for *read_positive().

[akpm@linux-foundation.org: tweak comment]
Signed-off-by: Shaohua Li &lt;shaohua.li@intel.com&gt;
Acked-by: Eric Dumazet &lt;eric.dumazet@gmail.com&gt;
Cc: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
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;

Original file line number	Diff line number	Diff line change
`@@ -75,7 +75,7 @@ static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)`
`75`	`75`	`barrier(); /* Prevent reloads of fbc->count */`
`76`	`76`	`if (ret >= 0)`
`77`	`77`	`return ret;`
`78`		`- return 1;`
	`78`	`+ return 0;`
`79`	`79`	`}`
`80`	`80`
`81`	`81`	`static inline int percpu_counter_initialized(struct percpu_counter *fbc)`
`@@ -133,6 +133,10 @@ static inline s64 percpu_counter_read(struct percpu_counter *fbc)`
`133`	`133`	`return fbc->count;`
`134`	`134`	`}`
`135`	`135`
	`136`	`+/*`
	`137`	`+ * percpu_counter is intended to track positive numbers. In the UP case the`
	`138`	`+ * number should never be negative.`
	`139`	`+ */`
`136`	`140`	`static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)`
`137`	`141`	`{`
`138`	`142`	`return fbc->count;`