From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760120Ab3D3CxT (ORCPT ); Mon, 29 Apr 2013 22:53:19 -0400 Received: from kirsty.vergenet.net ([202.4.237.240]:47749 "EHLO kirsty.vergenet.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760570Ab3D3CxG (ORCPT ); Mon, 29 Apr 2013 22:53:06 -0400 From: Simon Horman To: Eric Dumazet , Julian Anastasov , Ingo Molnar , Peter Zijlstra , "Paul E. McKenney" Cc: lvs-devel@vger.kernel.org, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, linux-kernel@vger.kernel.org, Pablo Neira Ayuso , Dipankar Sarma , Simon Horman Subject: [PATCH v2 1/2] sched: Add cond_resched_rcu_lock() helper Date: Tue, 30 Apr 2013 11:52:57 +0900 Message-Id: <1367290378-29224-2-git-send-email-horms@verge.net.au> X-Mailer: git-send-email 1.8.2.1 In-Reply-To: <1367290378-29224-1-git-send-email-horms@verge.net.au> References: <1367290378-29224-1-git-send-email-horms@verge.net.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is intended for use in loops which read data protected by RCU and may have a large number of iterations. Such an example is dumping the list of connections known to IPVS: ip_vs_conn_array() and ip_vs_conn_seq_next(). The call to cond_resched() is guarded by #ifndef CONFIG_PREEMPT_RCU as in the case of CONFIG_PREEMPT_RCU _rcu_read_unlock() will check to see if the RCU core needs to be informed, so there is no need to invoke cond_resched() in that case. Thanks to Paul E. McKenney for explaining this. cond_resched_rcu_lock() suggested by Eric Dumazet. ifndef guard suggested by Paul E. McKenney and Julian Anastasov. Cc: Eric Dumazet Cc: Paul E. McKenney Cc: Julian Anastasov Acked-by: Ingo Molnar Signed-off-by: Simon Horman --- v2 * Add guard the call to cond_resched() --- include/linux/sched.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/include/linux/sched.h b/include/linux/sched.h index e692a02..66da71c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2787,3 +2787,14 @@ static inline unsigned long rlimit_max(unsigned int limit) } #endif + +static void inline cond_resched_rcu_lock(void) +{ + if (need_resched()) { + rcu_read_unlock(); +#ifndef CONFIG_PREEMPT_RCU + cond_resched(); +#endif + rcu_read_lock(); + } +} -- 1.8.2.1