From: Paul E. McKenney Date: Wed, 12 Nov 2014 17:57:51 +0000 (-0800) Subject: rcu: Note quiescent state when CPU goes offline X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=3ba4d0e09bf965297e97adf195e0ea246cfe5c74;p=linux-beck.git rcu: Note quiescent state when CPU goes offline The rcu_cleanup_dead_cpu() function (called after a CPU has gone completely offline) has not reported a quiescent state because there was probably at least one synchronize_rcu() between the time the CPU went offline and the CPU_DEAD notifier, and this would have detected the CPU's offline state via quiescent-state forcing. However, the plan is for CPUs to take themselves offline, at which point it makes sense for them to report their own quiescent state. This commit makes this change in preparation for the new CPU-hotplug setup. Signed-off-by: Paul E. McKenney --- diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 5a0a4c969d38..24d3c67f7be7 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2297,7 +2297,7 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) rnp->qsmaskinit &= ~rdp->grpmask; if (rnp->qsmaskinit == 0 && !rcu_preempt_has_tasks(rnp)) rcu_cleanup_dead_rnp(rnp); - raw_spin_unlock_irqrestore(&rnp->lock, flags); + rcu_report_qs_rnp(rdp->grpmask, rsp, rnp, flags); /* Rlses rnp->lock. */ WARN_ONCE(rdp->qlen != 0 || rdp->nxtlist != NULL, "rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, nxtlist=%p\n", cpu, rdp->qlen, rdp->nxtlist);