From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933141Ab2FVPfn (ORCPT ); Fri, 22 Jun 2012 11:35:43 -0400 Received: from e9.ny.us.ibm.com ([32.97.182.139]:55041 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933087Ab2FVPfk (ORCPT ); Fri, 22 Jun 2012 11:35:40 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 08/17] rcu: Remove return value from rcu_assign_pointer() Date: Fri, 22 Jun 2012 08:35:03 -0700 Message-Id: <1340379312-6684-8-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.8 In-Reply-To: <1340379312-6684-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20120622153501.GA6626@linux.vnet.ibm.com> <1340379312-6684-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12062215-7182-0000-0000-000001D2BD6C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" The return value from rcu_assign_pointer() is not used, and using it would be quite ugly, for example: q = rcu_assign_pointer(global_p, p); To prevent this sort of ugliness from spreading, this commit wraps rcu_assign_pointer() in a do-while loop. Reported-by: Mathieu Desnoyers Reported-by: Josh Triplett Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- include/linux/rcupdate.h | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 267dc77..a58f382 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -514,10 +514,10 @@ static inline void rcu_preempt_sleep_check(void) (_________p1); \ }) #define __rcu_assign_pointer(p, v, space) \ - ({ \ + do { \ smp_wmb(); \ (p) = (typeof(*v) __force space *)(v); \ - }) + } while (0) /** @@ -852,7 +852,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) * * Assigns the specified value to the specified RCU-protected * pointer, ensuring that any concurrent RCU readers will see - * any prior initialization. Returns the value assigned. + * any prior initialization. * * Inserts memory barriers on architectures that require them * (which is most of them), and also prevents the compiler from -- 1.7.8