[PATCH 3.2 181/185] ftrace: Fix ftrace hash record update with notrace

Ben Hutchings
2013-12-29T02:08:44Z

From: Steven Rostedt <srostedt@redhat.com>

commit c842e975520f8ab09e293cc92f51a1f396251fd5 upstream.

When disabling the "notrace" records, that means we want to trace them.
If the notrace_hash is zero, it means that we want to trace all
records. But to disable a zero notrace_hash means nothing.

The check for the notrace_hash count was incorrect with:

if (hash && !hash->count)
return

With the correct comment above it that states that we do nothing
if the notrace_hash has zero count. But !hash also means that
the notrace hash has zero count. I think this was done to
protect against dereferencing NULL. But if !hash is true, then
we go through the following loop without doing a single thing.

Fix it to:

if (!hash || !hash->count)
return;

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
kernel/trace/ftrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1358,7 +1358,7 @@ static void __ftrace_hash_rec_update(str
* If the notrace hash has no items,
* then there's nothing to do.
*/
- if (hash && !hash->count)
+ if (!hash || !hash->count)
return;
}