Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756684Ab3JRQ5q (ORCPT ); Fri, 18 Oct 2013 12:57:46 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:63372 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753265Ab3JRQ5o (ORCPT ); Fri, 18 Oct 2013 12:57:44 -0400 MIME-Version: 1.0 In-Reply-To: <20131011131138.3bc5b2acf60df3a5d79d0d24@linux-foundation.org> References: <1381296747.2040.17.camel@joe-AO722> <20131011131138.3bc5b2acf60df3a5d79d0d24@linux-foundation.org> Date: Fri, 18 Oct 2013 09:57:43 -0700 Message-ID: Subject: Re: [RFC PATCH] device: Add kernel standard devm_k.alloc functions From: Kevin Hilman To: Andrew Morton Cc: Joe Perches , Tejun Heo , Greg KH , LKML , Sangjung Woo , Olof Johansson , Thierry Reding , Guenter Roeck , linux-arm-kernel Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3382 Lines: 101 On Fri, Oct 11, 2013 at 1:11 PM, Andrew Morton wrote: > On Tue, 08 Oct 2013 22:32:27 -0700 Joe Perches 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 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 --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/