linux-kernel - [PATCH 09/16] ftrace: Fix ftrace hash record update with notrace

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Message-Id: <20111221123807.707783878@goodmis.org>
Date:	Wed, 21 Dec 2011 07:36:33 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	linux-kernel@...r.kernel.org
Cc:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH 09/16] ftrace: Fix ftrace hash record update with notrace

From: Steven Rostedt <srostedt@...hat.com>

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@...dmis.org>
---
 kernel/trace/ftrace.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index dcd3a81..a383d6c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1381,7 +1381,7 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
 		 * If the notrace hash has no items,
 		 * then there's nothing to do.
 		 */
-		if (hash && !hash->count)
+		if (!hash || !hash->count)
 			return;
 	}

-- 
1.7.7.3

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