linux-kernel - Re: [PATCH] regulator: core: Move regulator release to avoid deadlock

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Message-ID: <20121031120117.GB27099@opensource.wolfsonmicro.com>
Date:	Wed, 31 Oct 2012 12:01:17 +0000
From:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
To:	Laxman Dewangan <ldewangan@...dia.com>
Cc:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	"lrg@...com" <lrg@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"patches@...nsource.wolfsonmicro.com" 
	<patches@...nsource.wolfsonmicro.com>
Subject: Re: [PATCH] regulator: core: Move regulator release to avoid
	deadlock

On Wed, Oct 31, 2012 at 04:03:59PM +0530, Laxman Dewangan wrote:
> On Monday 29 October 2012 09:44 PM, Mark Brown wrote:
>> * PGP Signed by an unknown key
>>
>> On Mon, Oct 29, 2012 at 09:33:33AM +0000, Charles Keepax wrote:
>>> regulator_put function was called whilst holding the
>>> regulator_list_mutex, which is also locked from regulator_put. This
>>> causes deadlock when failing to register a regulator.
>> Applied, thanks.
>
> This patch create the crash in following case:
> - If there is of rail supply and supply does not found. In this case it  
> goes to scrub and rdev->supply at this point shows NULL but when call  
> the function device_unregister(&rdev->dev), the rdev->supply becomes  
> random pointer.

Yeah that is a problem, sorry for missing this.

>
> What happen if we do the device_unregister() outside the mutex lock?

It would look reasonable to me, but I think it is going to make
more sense for someone with more experience than myself to have a
closer look at what can be done.
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