lkml.org 
[lkml]   [2014]   [Sep]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH tip/core/rcu 11/15] rcu: Break more call_rcu() deadlock involving scheduler and perf
On Thu, Aug 28, 2014 at 11:26:30AM -0700, Paul E. McKenney wrote:

> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index b6acb9340192..a1af86099a67 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -2121,16 +2121,23 @@ static void __call_rcu_nocb_enqueue(struct rcu_data *rdp,
> trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
> TPS("WakeEmpty"));
> } else {
> - rdp->nocb_defer_wakeup = true;
> + rdp->nocb_defer_wakeup = RCU_NOGP_WAKE;
> trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
> TPS("WakeEmptyIsDeferred"));
> }
> rdp->qlen_last_fqs_check = 0;
> } else if (len > rdp->qlen_last_fqs_check + qhimark) {
> /* ... or if many callbacks queued. */
> - wake_nocb_leader(rdp, true);
> + if (!irqs_disabled_flags(flags)) {
> + wake_nocb_leader(rdp, true);
> + trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
> + TPS("WakeOvf"));
> + } else {
> + rdp->nocb_defer_wakeup = RCU_NOGP_WAKE_FORCE;
> + trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
> + TPS("WakeOvfIsDeferred"));
> + }
> rdp->qlen_last_fqs_check = LONG_MAX / 2;
> - trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, TPS("WakeOvf"));
> } else {
> trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu, TPS("WakeNot"));
> }

Is it possible for the RCU_NOCP_WAKE write to overwrite a WAKE_FORCE ?
If not, why not? (Would make a good comment thereabouts).


\
 
 \ /
  Last update: 2014-09-01 13:41    [W:0.167 / U:0.348 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site