Return-path: Received: from ra.tuxdriver.com ([70.61.120.52]:4595 "EHLO ra.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755261AbYBGTjN (ORCPT ); Thu, 7 Feb 2008 14:39:13 -0500 Date: Thu, 7 Feb 2008 14:08:42 -0500 From: "John W. Linville" To: Andrew Morton Cc: Russell King - ARM Linux , deller@gmx.de, jt@hpl.hp.com, rjw@sisk.pl, linux-wireless@vger.kernel.org, linux-arm-kernel@lists.arm.linux.org.uk Subject: Re: [PATCH] WAVELAN - compile-time check for struct sizes Message-ID: <20080207190842.GC3025@tuxdriver.com> (sfid-20080207_193917_578298_BAD63706) References: <200801131516.34567.deller@gmx.de> <20080202224515.20a09553.akpm@linux-foundation.org> <200802062150.23930.deller@gmx.de> <20080206130448.564f18bb.akpm@linux-foundation.org> <20080206214747.GG32245@flint.arm.linux.org.uk> <20080206135950.d48ffa36.akpm@linux-foundation.org> <20080207155152.GA3025@tuxdriver.com> <20080207104912.c719deed.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20080207104912.c719deed.akpm@linux-foundation.org> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thu, Feb 07, 2008 at 10:49:12AM -0800, Andrew Morton wrote: > On Thu, 7 Feb 2008 10:51:52 -0500 "John W. Linville" wrote: > > > On Wed, Feb 06, 2008 at 01:59:50PM -0800, Andrew Morton wrote: > > > On Wed, 6 Feb 2008 21:47:47 +0000 > > > Russell King - ARM Linux wrote: > > > > > > I assume that it's the second BUILD_BUG_ON() which is triggering? > > > > > > yup. > > > > > > > Given that: > > > > > > > > #define MMW_SIZE 37 > > > > > > > > is not a multiple of sizeof(unsigned long) this is hardly surprising. > > > > > > > > If structures are used to define a layout of something and must not > > > > contain compiler padding, it must be packed. Given these structures > > > > contain just unsigned char, there's no concerns about >8bit loads > > > > becoming less efficient. > > > > Does a patch like this suffice? I haven't checked whether such a > > patch implies that the BUILD_BUG_ON()'s become unnecessary... > > With your patch applied and arm allmodconfig, this > > BUILD_BUG_ON(sizeof(ha_t) != HA_SIZE); > > triggers > > Without your patch applied, these two > > BUILD_BUG_ON(sizeof(mmw_t) != MMW_SIZE); > BUILD_BUG_ON(sizeof(ha_t) != HA_SIZE); > > are triggering. The ha_t one triggers either way? Hmmm... Russell suggested that the ha_t and psa_t packed attributes were unnecessary, so I'll include the reduced version just in case the above is a typo. --- From: John W. Linville Subject: [PATCH] wavelan: mark hardware interfacing structures as packed Signed-off-by: John W. Linville --- drivers/net/wireless/wavelan.h | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/wavelan.h b/drivers/net/wireless/wavelan.h index 27172cd..fde4613 100644 --- a/drivers/net/wireless/wavelan.h +++ b/drivers/net/wireless/wavelan.h @@ -292,7 +292,7 @@ struct mmw_t #define MMW_EXT_ANT_INTERNAL 0x00 /* Internal antenna */ #define MMW_EXT_ANT_EXTERNAL 0x03 /* External antenna */ #define MMW_EXT_ANT_IQ_TEST 0x1C /* IQ test pattern (set to 0) */ -}; +} __attribute__ ((packed));; #define MMW_SIZE 37 @@ -347,7 +347,7 @@ struct mmr_t unsigned char mmr_unused4[1]; /* unused */ unsigned char mmr_fee_data_l; /* Read data from EEPROM (low) */ unsigned char mmr_fee_data_h; /* Read data from EEPROM (high) */ -}; +} __attribute__ ((packed)); #define MMR_SIZE 36 -- 1.5.3.3 -- John W. Linville linville@tuxdriver.com