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From: Tejun Heo <tj@kernel.org>
To: Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH] scheduler: convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()s
Date: Mon, 18 Mar 2013 12:22:34 -0700
Message-ID: <20130318192234.GD3042@htj.dyndns.org> (raw)

try_to_wake_up_local() should only be invoked to wake up another task
in the same runqueue and BUG_ON()s are used to enforce the rule.
Missing try_to_wake_up_local() can stall workqueue execution but such
stalls are likely to be finite either by another work item being
queued or the one blocked getting unblocked.  There's no reason to
trigger BUG while holding rq lock crashing the whole system.

Convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()s.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/sched/core.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7f12624..a2eda4d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1498,8 +1498,10 @@ static void try_to_wake_up_local(struct task_struct *p)
 {
 	struct rq *rq = task_rq(p);
 
-	BUG_ON(rq != this_rq());
-	BUG_ON(p == current);
+	if (WARN_ON_ONCE(rq != this_rq()) ||
+	    WARN_ON_ONCE(p == current))
+		return;
+
 	lockdep_assert_held(&rq->lock);
 
 	if (!raw_spin_trylock(&p->pi_lock)) {

             reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-18 19:22 Tejun Heo [this message]
2013-03-18 19:32 ` Steven Rostedt
2013-03-19 10:14 ` Peter Zijlstra
2013-03-19 11:29   ` Steven Rostedt
2013-03-21 18:14 ` [tip:sched/urgent] sched: Convert BUG_ON() s " tip-bot for Tejun Heo

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