From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932295AbbHDHz7 (ORCPT ); Tue, 4 Aug 2015 03:55:59 -0400 Received: from e06smtp14.uk.ibm.com ([195.75.94.110]:60976 "EHLO e06smtp14.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932236AbbHDHz4 (ORCPT ); Tue, 4 Aug 2015 03:55:56 -0400 X-Helo: d06dlp01.portsmouth.uk.ibm.com X-MailFrom: borntraeger@de.ibm.com X-RcptTo: linux-kernel@vger.kernel.org From: Christian Borntraeger To: Peter Zijlstra Cc: Andrey Konovalov , Ingo Molnar , Paul McKenney , linux-kernel@vger.kernel.org, Christian Borntraeger Subject: [PATCH] compiler.h: cast away attributes in WRITE_ONCE magic Date: Tue, 4 Aug 2015 09:55:48 +0200 Message-Id: <1438674948-38310-2-git-send-email-borntraeger@de.ibm.com> X-Mailer: git-send-email 2.3.8 In-Reply-To: <1438674948-38310-1-git-send-email-borntraeger@de.ibm.com> References: <1438674948-38310-1-git-send-email-borntraeger@de.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15080407-0017-0000-0000-000004F216FD Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org kernel build bot showed a warning triggered by commit 76695af20c01 ("locking, arch: use WRITE_ONCE()/READ_ONCE() in smp_store_release()/smp_load_acquire()"). Turns out that sparse does not like WRITE_ONCE accessing elements from the (sparse) rcu address space. fs/afs/inode.c:448:9: sparse: incorrect type in initializer (different address spaces) fs/afs/inode.c:448:9: expected struct afs_permits *__val fs/afs/inode.c:448:9: got void [noderef] * Solution is to force cast away the sparse attributes for the initializer of the union in WRITE_SAME. As this now gets too long, lets split the macro. Signed-off-by: Christian Borntraeger --- include/linux/compiler.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index e08a6ae..c836eb2 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -252,7 +252,12 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; }) #define WRITE_ONCE(x, val) \ - ({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; __write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; }) +({ \ + union { typeof(x) __val; char __c[1]; } __u = \ + { .__val = (__force typeof(x)) (val) }; \ + __write_once_size(&(x), __u.__c, sizeof(x)); \ + __u.__val; \ +}) /** * READ_ONCE_CTRL - Read a value heading a control dependency -- 2.3.8