From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Borntraeger Subject: [PATCH 2/2] compiler.h: Fix word size check for READ/WRITE_ONCE Date: Wed, 25 Mar 2015 14:15:36 +0100 Message-ID: <1427289336-22883-3-git-send-email-borntraeger@de.ibm.com> References: <1427289336-22883-1-git-send-email-borntraeger@de.ibm.com> Return-path: Received: from e06smtp13.uk.ibm.com ([195.75.94.109]:42413 "EHLO e06smtp13.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751912AbbCYNPn (ORCPT ); Wed, 25 Mar 2015 09:15:43 -0400 Received: from /spool/local by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 25 Mar 2015 13:15:41 -0000 In-Reply-To: <1427289336-22883-1-git-send-email-borntraeger@de.ibm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, torvalds@linux-foundation.org, paulmck@linux.vnet.ibm.com, linux-s390@vger.kernel.org, Russell King , Christian Borntraeger Turns out that my last rework for the word size check broke it: I originally had the size > wordsize check in __read_once_size/ /__write_once_size as empty extern function in a newly created file lib/access.c and marked it with a __compiletime_warning. Unfortunately this broke arm rpcdefconfig due to this line CFLAGS_font.o := -Dstatic= in arch/arm/boot/compressed/Makefile. This define made it impossible for the compiler to get rid of the unused __write_once_size and __read_once_size and the linker complained about the missing data_access_exceeds_word_size as the compressed boot thing did not include lib/access.o. So I wanted to be clever and changed data_access_exceeds_word_size to a static inline function. Turns out that this actually disabled the compiletime warning. Next try, have it as a weak function. This actually does enable the warning. It will create an empty data_access_exceeds_word_size function in each object file, though and it will trigger a warning for arm rpcdefconfig: CC arch/arm/boot/compressed/font.o include/linux/compiler.h: In function '__write_once_size': include/linux/compiler.h:231: warning: call to 'data_access_exceeds_word_size' declared with attribute warning: data access exceeds word size and won't be atomic include/linux/compiler.h: In function '__read_once_size': include/linux/compiler.h:214: warning: call to 'data_access_exceeds_word_size' declared with attribute warning: data access exceeds word size and won't be atomic Signed-off-by: Christian Borntraeger --- include/linux/compiler.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 1b45e4a..37943c4 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -192,13 +192,10 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); #include -static __always_inline void data_access_exceeds_word_size(void) #ifdef __compiletime_warning __compiletime_warning("data access exceeds word size and won't be atomic") #endif -; - -static __always_inline void data_access_exceeds_word_size(void) +__weak notrace void data_access_exceeds_word_size(void) { } -- 2.1.4