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

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Message-ID: <1281532297.2067.8.camel@cowboy>
Date:	Wed, 11 Aug 2010 09:11:37 -0400
From:	Davidlohr Bueso <dave@....org>
To:	Jiri Kosina <jkosina@...e.cz>
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, 2010-08-11 at 15:06 +0200, Jiri Kosina wrote:
> 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).
> 

Ok, makes sense. I was a bit doubtful about the unlikely(), thanks for
the review.

Davidlohr

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