Messages in this thread Patch in this message | | | Date | Fri, 18 Oct 2013 09:57:43 -0700 | Subject | Re: [RFC PATCH] device: Add kernel standard devm_k.alloc functions | From | Kevin Hilman <> |
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On Fri, Oct 11, 2013 at 1:11 PM, Andrew Morton <akpm@linux-foundation.org> wrote: > On Tue, 08 Oct 2013 22:32:27 -0700 Joe Perches <joe@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 <khilman@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 <khilman@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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