On Fri, Oct 11, 2013 at 1:11 PM, Andrew Morton
<a...@linux-foundation.org> wrote:
> On Tue, 08 Oct 2013 22:32:27 -0700 Joe Perches <j...@perches.com> wrote:
>
>> Currently, devm_ managed memory only supports kzalloc.
>>
>> Convert the devm_kzalloc implementation to devm_kmalloc
>> and remove the complete memset to 0 but still set the
>> initial struct devres header and whatever padding before
>> data to 0.
>>
>> Add the other normal alloc variants as static inlines with
>> __GFP_ZERO added to the gfp flag where appropriate:
>>
>> devm_kzalloc
>> devm_kcalloc
>> devm_kmalloc_array
>>
>> Add gfp.h to device.h for the newly added static inlines.
>>
>> ...
>>
>> --- a/drivers/base/devres.c
>> +++ b/drivers/base/devres.c
>> @@ -91,7 +91,8 @@ static __always_inline struct devres *
>> alloc_dr(dr_release_t release,
>> if (unlikely(!dr))
>> return NULL;
>>
>> - memset(dr, 0, tot_size);
>> + memset(dr, 0, offsetof(struct devres, data));
>
> Well, this does make some assumptions about devres layout. It would
> have been cleaner to do
>
> memset(&dr.node, 0, sizeof(dr.node));
>
> but whatever.
>
> I made some changelog changes.
>
> I agree that including devm_kmalloc_array() might be going a bit far
> (it's the lack of devm_kmalloc which matters most). But
> devm_kmalloc_array() is inlined and is hence basically cost-free until
> someone actually uses it.
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.
Kevin
[1]
>From 16489e16c8efdda791e96bd591e455e7c7739f98 Mon Sep 17 00:00:00 2001
From: Kevin Hilman <khil...@linaro.org>
Date: Fri, 18 Oct 2013 09:41:39 -0700
Subject: [PATCH] devres: restore zeroing behavior of devres_alloc()
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.
Signed-off-by: Kevin Hilman <khil...@linaro.org>
---
drivers/base/devres.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index 37e67a2..e3fe8be 100644
--- 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;
--
1.8.3
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