linux-kernel - Re: [RFC PATCH] device: Add kernel standard devm

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Message-ID: <CAGa+x87cDqigMAGb+7+46Ea1dRMWDi1O_84JZsmOKRb=1dSfTQ@mail.gmail.com>
Date:	Fri, 18 Oct 2013 10:11:27 -0700
From:	Kevin Hilman <khilman@...aro.org>
To:	Joe Perches <joe@...ches.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Sangjung Woo <sangjung.woo@...sung.com>,
	Olof Johansson <olof@...om.net>,
	Thierry Reding <thierry.reding@...il.com>,
	Guenter Roeck <linux@...ck-us.net>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC PATCH] device: Add kernel standard devm_k.alloc functions

On Fri, Oct 18, 2013 at 10:06 AM, Joe Perches <joe@...ches.com> wrote:
> On Fri, 2013-10-18 at 09:57 -0700, Kevin Hilman wrote:
> []
>> A handful of boot panics on ARM platforms were bisected to point at
>> the version of this commit that's in linux-next (commit
>> 64c862a839a8db2c02bbaa88b923d13e1208919d).  Reverting this commit
>> makes things happy again.
>>
>> Upon further digging, it seems that users of devres_alloc() are
>> relying on the previous behavior of having the memory zero'd which is
>> no longer the case after $SUBJECT patch.  The change below on top of
>> -next makes these ARM boards happy again.
> []
>> commit 64c862a8 (devres: add kernel standard devm_k.alloc functions) changed
>> the default behavior of alloc_dr() to no longer zero the allocated
>> memory.  However,
>> only the devm.k.alloc() function were modified to pass in __GFP_ZERO
>> which leaves
>> any users of devres_alloc() or __devres_alloc() with potentially wrong
>> assumptions
>> about memory being zero'd upon allocation.
>>
>> To fix, add __GFP_ZERO to devres_alloc() calls to preserve previous
>> behavior of zero'ing memory upon allocation.
> []
>> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> []
>> @@ -136,7 +136,7 @@ void * devres_alloc(dr_release_t release, size_t
>> size, gfp_t gfp)
>>  {
>>   struct devres *dr;
>>
>> - dr = alloc_dr(release, size, gfp);
>> + dr = alloc_dr(release, size, gfp | __GFP_ZERO);
>>   if (unlikely(!dr))
>>   return NULL;
>>   return dr->data;
>
> Wouldn't the __devres_alloc need that too?

Yeah,  I had mentioned __devres_alloc() in the changelog, but missed
it in the actual patch. :(
Anyways, I had quickly sent an updated patch, but our mails must've
crossed paths.

Kevin
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