From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755047Ab1HOPx6 (ORCPT ); Mon, 15 Aug 2011 11:53:58 -0400 Received: from mail-vw0-f46.google.com ([209.85.212.46]:46598 "EHLO mail-vw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754879Ab1HOPxz (ORCPT ); Mon, 15 Aug 2011 11:53:55 -0400 From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Andrew Morton , Anton Blanchard , Avi Kivity , Ingo Molnar , Lai Jiangshan , "Paul E . McKenney" , Paul Menage , Peter Zijlstra , Stephen Hemminger , Thomas Gleixner , Tim Pepper Subject: [PATCH 22/32] rcu: Restart tick if we enqueue a callback in a nohz/cpuset CPU Date: Mon, 15 Aug 2011 17:52:19 +0200 Message-Id: <1313423549-27093-23-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1313423549-27093-1-git-send-email-fweisbec@gmail.com> References: <1313423549-27093-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If we enqueue an rcu callback, we need the CPU tick to stay alive until we take care of those by completing the appropriate grace period. Thus, when we call_rcu(), send a self IPI that checks rcu_needs_cpu() so that we restore a periodic tick behaviour that can take care of everything. Signed-off-by: Frederic Weisbecker Cc: Andrew Morton Cc: Anton Blanchard Cc: Avi Kivity Cc: Ingo Molnar Cc: Lai Jiangshan Cc: Paul E . McKenney Cc: Paul Menage Cc: Peter Zijlstra Cc: Stephen Hemminger Cc: Thomas Gleixner Cc: Tim Pepper --- kernel/rcutree.c | 8 ++++++++ 1 files changed, 8 insertions(+), 0 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index d496c70..b5643ce2 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -51,6 +51,7 @@ #include #include #include +#include #include "rcutree.h" @@ -1546,6 +1547,13 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), rdp->nxttail[RCU_NEXT_TAIL] = &head->next; rdp->qlen++; + /* Restart the timer if needed to handle the callbacks */ + if (tick_nohz_adaptive_mode()) { + /* Make updates on nxtlist visible to self IPI */ + barrier(); + smp_cpuset_update_nohz(smp_processor_id()); + } + /* If interrupts were disabled, don't dive into RCU core. */ if (irqs_disabled_flags(flags)) { local_irq_restore(flags); -- 1.7.5.4