From: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
When setting up an in-the-future "advanced" grace period, the code needs
to wake up the relevant grace-period kthread, which it currently does
unconditionally. However, this results in needless wakeups in the case
where the advanced grace period is being set up by the grace-period
kthread itself, which is a non-uncommon situation. This commit therefore
checks to see if the running thread is the grace-period kthread, and
avoids doing the irq_work_queue()-mediated wakeup in that case.
Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <j...@joshtriplett.org>
---
kernel/rcutree.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 9184056..c6a064a 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1576,10 +1576,12 @@ rcu_start_gp_advanced(struct rcu_state *rsp, struct
rcu_node *rnp,
/*
* We can't do wakeups while holding the rnp->lock, as that
- * could cause possible deadlocks with the rq->lock. Deter
- * the wakeup to interrupt context.
+ * could cause possible deadlocks with the rq->lock. Defer
+ * the wakeup to interrupt context. And don't bother waking
+ * up the running kthread.
*/
- irq_work_queue(&rsp->wakeup_work);
+ if (current != rsp->gp_kthread)
+ irq_work_queue(&rsp->wakeup_work);
}
/*
--
1.8.1.5
--
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