linux-kernel - Re: [PATCH] jbd: Remove redundant NULL check upon kfree()

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Date:	Wed, 11 Aug 2010 15:06:36 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Davidlohr Bueso <dave@....org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] jbd: Remove redundant NULL check upon kfree()

On Wed, 11 Aug 2010, Davidlohr Bueso wrote:

> jbd: Remove redundant NULL check upon kfree().
> 
> Signed-off-by: Davidlohr Bueso <dave@....org>
> ---
>  fs/jbd/transaction.c |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c
> index 5ae71e7..5e98130 100644
> --- a/fs/jbd/transaction.c
> +++ b/fs/jbd/transaction.c
> @@ -232,8 +232,7 @@ repeat_locked:
>  
>  	lock_map_acquire(&handle->h_lockdep_map);
>  out:
> -	if (unlikely(new_transaction))		/* It's usually NULL */
> -		kfree(new_transaction);
> +	kfree(new_transaction);

This doesn't seem entirely redundant, as it is optimized (via the 
unlikely() hint) for the opposite case than what kfree() is optimized for 
(kfree() assumes that the pointer is likely non-NULL, while the code above 
assumes that the pointer si likely NULL).

-- 
Jiri Kosina
SUSE Labs, Novell Inc.

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