linux-kernel - Re: [PATCH] drivers: virtio: Use PTR

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Message-ID: <87620ecvds.fsf@rustcorp.com.au>
Date:	Tue, 26 Mar 2013 20:53:27 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Andru Gheorghiu <gheorghiuandru@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Michael S. Tsirkin" <mst@...hat.com>,
	virtualization@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
Subject: Re: [PATCH] drivers: virtio: Use PTR_RET function

Andru Gheorghiu <gheorghiuandru@...il.com> writes:
> PTR_RET does return. It's perfectly equivalent to using IS_ERR and the
> returning PTR_ERR. The implementation is here [1].

Um, I read the implementation, thanks.

> The reason for using it is this: if you have a function that does
> something why not call it instead of reproducing it's behavior by
> explicitly writing what it does.

Because clarity matters, and this function makes callers less clear.
It's the most breathtakingly bad name since BUILD_BUG_ON_ZERO().

Why not change PTR_ERR to return 0 if !IS_ERR()?  Noone breaks, gcc
probably produces the same code, and noone needs to learn your weird
new kernel meme.

In fact, as gcc will produce the same code for "if (PTR_ERR(p))" as it
does for "if (IS_ERR(p))", you get to be one of the very, very few
people who have ever *reduced* the complexity of a kernel interface.

Cheers,
Rusty.
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