linux-kernel - Re: [PATCH] ftrace: Remove a superfluous check

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Date:	Thu, 29 Mar 2012 19:11:40 +0200
From:	Borislav Petkov <bp@...64.org>
To:	John Kacur <jkacur@...hat.com>
Cc:	Borislav Petkov <bp@...64.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ftrace: Remove a superfluous check

On Thu, Mar 29, 2012 at 07:03:23PM +0200, John Kacur wrote:
> If you're going to do this, then you can drop the label too.

Jahaa... thanks.

Here's an updated patch:

--
>From 135c25a609739bbdf1c33e62119517b47f0e1d07 Mon Sep 17 00:00:00 2001
From: Borislav Petkov <borislav.petkov@....com>
Date: Thu, 29 Mar 2012 18:41:15 +0200
Subject: [PATCH] ftrace: Remove a superfluous check

register_ftrace_function() checks ftrace_disabled and calls
__register_ftrace_function which does it again.

Drop the first check and add the unlikely hint to the second one. Also,
drop the label as John correctly notices.

No functional change.

Cc: John Kacur <jkacur@...hat.com>
Signed-off-by: Borislav Petkov <borislav.petkov@....com>
---
 kernel/trace/ftrace.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 867bd1dd2dd0..0df8f8088ffe 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -311,7 +311,7 @@ static int remove_ftrace_list_ops(struct ftrace_ops **list,
 
 static int __register_ftrace_function(struct ftrace_ops *ops)
 {
-	if (ftrace_disabled)
+	if (unlikely(ftrace_disabled))
 		return -ENODEV;
 
 	if (FTRACE_WARN_ON(ops == &global_ops))
@@ -4304,16 +4304,12 @@ int register_ftrace_function(struct ftrace_ops *ops)
 
 	mutex_lock(&ftrace_lock);
 
-	if (unlikely(ftrace_disabled))
-		goto out_unlock;
-
 	ret = __register_ftrace_function(ops);
 	if (!ret)
 		ret = ftrace_startup(ops, 0);
 
-
- out_unlock:
 	mutex_unlock(&ftrace_lock);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(register_ftrace_function);
-- 
1.7.9.3.362.g71319



-- 
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
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