[RFC] device: Add kernel standard devm_k.alloc functions

Commit Message

Kevin Hilman Oct. 18, 2013, 5:04 p.m. UTC

> 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.

Oops, it should've fixed __devres_alloc() also.  Updated patch below.

Kevin

From a1962ed4a999fb630a48f75a5ecaf84401d5dbfc Mon Sep 17 00:00:00 2001
From: Kevin Hilman <[e-mail]>
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 <[e-mail]>
---
 drivers/base/devres.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

  set_node_dbginfo(&dr->node, name, size);
@@ -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;

Comments

Greg KH Oct. 18, 2013, 10:57 p.m. UTC | #1

On Fri, Oct 18, 2013 at 10:04:11AM -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.
> 
> Oops, it should've fixed __devres_alloc() also.  Updated patch below.

Can you send this in a format that I can apply it in?  It was whitespace
damaged.

thanks,

greg k-h

Patch

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index 37e67a2..545c4de 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -111,7 +111,7 @@  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;