linux-kernel - Re: [PATCH 5/5] driver core: let dev_set_drvdata return int instead of void as it can fail

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Message-ID: <BANLkTik29+u0A-uuQG3KtjQxNO_KpBMShg@mail.gmail.com>
Date:	Wed, 6 Apr 2011 13:41:01 +0200
From:	Michał Mirosław <mirqus@...il.com>
To:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
Cc:	Greg KH <gregkh@...e.de>, linux-arm-kernel@...ts.infradead.org,
	shiraz.hashim@...com, linux-kernel@...r.kernel.org,
	kernel@...gutronix.de
Subject: Re: [PATCH 5/5] driver core: let dev_set_drvdata return int instead
 of void as it can fail

2011/4/6 Uwe Kleine-König <u.kleine-koenig@...gutronix.de>:
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> ---
> Hello,
>
> I wasn't sure what to return when dev_set_drvdata is called with
> dev=NULL.  I choosed 0, but -EINVAL would be OK for me, too. What do you
> think?

This code was introduced by:

commit b4028437876866aba4747a655ede00f892089e14
Author: Greg Kroah-Hartman <gregkh@...e.de>
Date:   Mon May 11 14:16:57 2009 -0700

    Driver core: move dev_get/set_drvdata to drivers/base/dd.c

Before this patch, driver writers could assume that dev_set_drvdata()
never fails. And, dev==NULL would cause an imediate NULL dereference
(equivalent to BUG_ON(!dev), BTW). And, if dev_set_drvdata() fails
(silently as it is now) it's going to BUG later anyway.

I think it's best to revert that commit instead of fixing this up.

Best Regards,
Michał Mirosław
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