linux-kernel - Re: [PATCH v2] driver core: let dev_set_drvdata return int instead of void as it can fail

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Message-ID: <BANLkTi=q8jfEaLByZVZPHHYp_5PTK-36cw@mail.gmail.com>
Date:	Wed, 20 Apr 2011 11:09:56 +0200
From:	Michał Mirosław <mirqus@...il.com>
To:	Greg KH <greg@...ah.com>
Cc:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>, Greg KH <gregkh@...e.de>,
	linux-kernel@...r.kernel.org, kernel@...gutronix.de,
	Viresh Kumar <viresh.kumar@...com>,
	linux-arm-kernel@...ts.infradead.org, shiraz.hashim@...com
Subject: Re: [PATCH v2] driver core: let dev_set_drvdata return int instead of
 void as it can fail

2011/4/20 Greg KH <greg@...ah.com>:
> On Mon, Apr 11, 2011 at 08:42:58PM +0200, Uwe Kleine-König wrote:
>> Before commit
>>
>>       b402843 (Driver core: move dev_get/set_drvdata to drivers/base/dd.c)
>>
>> calling dev_set_drvdata with dev=NULL was an unchecked error. After some
>> discussion about what to return in this case removing the check (and so
>> producing a null pointer exception) seems fine.
> I'm confused by this thread, care to resend all of these in a series
> against the latest linux-next tree?

I'd argue that dev_set_drvdata() should never fail. All current
drivers depend on this, and if dev_set_drvdata() fails, user will get
an OOPS a short while after the device finishes initializing (or maybe
even before that if callbacks are involved).
Allowing dev_set_drvdata() to fail will need putting a lot of
boilerplate code into drivers for no real gain.

Please consider reverting commit
b4028437876866aba4747a655ede00f892089e14 instead of "fixing" issues it
generates.

Best Regards,
Michał Mirosław
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