Commit-ID: 1772947bd0126661866069157e95197e9c0020e9 Gitweb: http://git.kernel.org/tip/1772947bd0126661866069157e95197e9c0020e9 Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> AuthorDate: Tue, 12 Aug 2014 11:27:31 -0700 Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> CommitDate: Tue, 16 Sep 2014 10:08:03 -0700 rcu: Handle NOCB callbacks from irq-disabled idle code If an RCU callback is queued on a no-CBs CPU from idle code with irqs disabled, and if that CPU stays idle forever after, the callback will never be invoked. This commit therefore adds a check for this situation in ____call_rcu_nocb(), invoking the RCU core solely for the purpose of the ensuing return-to-idle transition. (If the CPU doesn't return to idle, the next scheduling-clock interrupt will fix things up.) Reported-by: Amit Shah <amit.shah@xxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Tested-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx> --- kernel/rcu/tree_plugin.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 4ad63d8..8b73518 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2129,6 +2129,17 @@ static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp, trace_rcu_callback(rdp->rsp->name, rhp, -atomic_long_read(&rdp->nocb_q_count_lazy), -atomic_long_read(&rdp->nocb_q_count)); + + /* + * If called from an extended quiescent state with interrupts + * disabled, invoke the RCU core in order to allow the idle-entry + * deferred-wakeup check to function. + */ + if (irqs_disabled_flags(flags) && + !rcu_is_watching() && + cpu_online(smp_processor_id())) + invoke_rcu_core(); + return true; } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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