linux-kernel - Re: [PATCH net] packet: bail out of packet

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Date:	Sun, 11 Jan 2015 14:34:04 -0500
From:	Christoph Jaeger <cj@...ux.com>
To:	Joe Perches <joe@...ches.com>
Cc:	Alan <alan@...ux.intel.com>, davem@...emloft.net,
	willemb@...gle.com, edumazet@...gle.com, dborkman@...hat.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] packet: bail out of packet_snd() if L2 header
 creation fails

On Sun, Jan 11, 2015 at 10:52:25AM -0800, Joe Perches wrote:
> On Sun, 2015-01-11 at 13:01 -0500, Christoph Jaeger wrote:
> > Due to a misplaced parenthesis, the expression
> > 
> >   (unlikely(offset) < 0),
> > 
> > which expands to
> > 
> >   (__builtin_expect(!!(offset), 0) < 0),
> 
> Here's another one:
> 
> drivers/platform/goldfish/goldfish_pipe.c:285:	if (unlikely(bufflen) == 0)

Well, the conditional statement works as intended. Of course, the branch
prediction doesn't.

Coccinelle should be able to check for this kind of likely()/unlikely() usage,
shouldn't it?

~Christoph
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