From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755416AbbHLMet (ORCPT ); Wed, 12 Aug 2015 08:34:49 -0400 Received: from terminus.zytor.com ([198.137.202.10]:42588 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751652AbbHLMeq (ORCPT ); Wed, 12 Aug 2015 08:34:46 -0400 Date: Wed, 12 Aug 2015 05:34:08 -0700 From: tip-bot for Christian Borntraeger Message-ID: Cc: tglx@linutronix.de, andreyknvl@google.com, hpa@zytor.com, borntraeger@de.ibm.com, peterz@infradead.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, mingo@kernel.org, paulmck@linux.vnet.ibm.com Reply-To: paulmck@linux.vnet.ibm.com, mingo@kernel.org, hpa@zytor.com, borntraeger@de.ibm.com, torvalds@linux-foundation.org, peterz@infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, andreyknvl@google.com In-Reply-To: <1438674948-38310-2-git-send-email-borntraeger@de.ibm.com> References: <1438674948-38310-2-git-send-email-borntraeger@de.ibm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] locking, compiler.h: Cast away attributes in the WRITE_ONCE() magic Git-Commit-ID: ba33034fffc1189d95301bd865f1c799256e72a2 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: ba33034fffc1189d95301bd865f1c799256e72a2 Gitweb: http://git.kernel.org/tip/ba33034fffc1189d95301bd865f1c799256e72a2 Author: Christian Borntraeger AuthorDate: Tue, 4 Aug 2015 09:55:48 +0200 Committer: Ingo Molnar CommitDate: Wed, 12 Aug 2015 11:58:58 +0200 locking, compiler.h: Cast away attributes in the WRITE_ONCE() magic The kernel build bot showed a new warning triggered by commit: 76695af20c01 ("locking, arch: use WRITE_ONCE()/READ_ONCE() in smp_store_release()/smp_load_acquire()") because 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_ONCE(). (And as this now gets too long, also split the macro into multiple lines.) Signed-off-by: Christian Borntraeger Signed-off-by: Peter Zijlstra (Intel) Cc: Andrey Konovalov Cc: Linus Torvalds Cc: Paul McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1438674948-38310-2-git-send-email-borntraeger@de.ibm.com Signed-off-by: Ingo Molnar --- 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