From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Horman Subject: [PATCH v3 1/2] sched: Add cond_resched_rcu_lock() helper Date: Wed, 1 May 2013 17:57:52 +0900 Message-ID: <1367398673-1253-2-git-send-email-horms@verge.net.au> References: <1367398673-1253-1-git-send-email-horms@verge.net.au> 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 To: Eric Dumazet , Julian Anastasov , Ingo Molnar , Peter Zijlstra , "Paul E. McKenney" Return-path: In-Reply-To: <1367398673-1253-1-git-send-email-horms@verge.net.au> Sender: lvs-devel-owner@vger.kernel.org List-Id: netdev.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 --- v3 * Remove if (need_resched()), it is no longer needed with the guard added in v2. v2 * Guard the call to cond_resched() with #ifndef CONFIG_PREEMPT_RCU --- include/linux/sched.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/include/linux/sched.h b/include/linux/sched.h index e692a02..79cfe6d 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2787,3 +2787,12 @@ static inline unsigned long rlimit_max(unsigned int limit) } #endif + +static void inline cond_resched_rcu_lock(void) +{ + rcu_read_unlock(); +#ifndef CONFIG_PREEMPT_RCU + cond_resched(); +#endif + rcu_read_lock(); +} -- 1.8.2.1