linux-kernel - Re: [PATCH] af_unix: Don't set err in unix_stream_read

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Date:	Sat, 13 Feb 2016 00:18:49 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Rainer Weikusat <rweikusat@...ileactivedefense.com>,
	"davem@...emloft.net" <davem@...emloft.net>
Cc:	hannes@...essinduktion.org, edumazet@...gle.com,
	dhowells@...hat.com, ying.xue@...driver.com,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>,
	Joseph Salisbury <joseph.salisbury@...onical.com>
Subject: Re: [PATCH] af_unix: Don't set err in unix_stream_read_generic
 unless there was an error

On Fri, 2016-02-05 at 22:30 +0000, Rainer Weikusat wrote:
> The present unix_stream_read_generic contains various code sequences of
> the form
> 
> err = -EDISASTER;
> if ()
> 	goto out;
[...]

I wish people would stop writing code like this.  At one time it may
have been a useful micro-optimisation, avoiding an extra branch in the
successful case, but gcc now appears to do that itself.  So it makes
the code less clear and runs the risk of introducing this sort of bug,
for no obvious benefit.

Ben.

-- 
Ben Hutchings
Sturgeon's Law: Ninety percent of everything is crap.
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