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authorMarcel Ziswiler <marcel.ziswiler@toradex.com>2019-03-28 16:27:49 +0100
committerMarcel Ziswiler <marcel.ziswiler@toradex.com>2019-03-28 16:27:49 +0100
commitd899927728beca8357a5b4120b690cb3c1d80844 (patch)
treeccb170439cc8638d71f6120ae08a6faded46db98 /kernel/rcu/tree.c
parent8d60367808c45e33c0a9127621f4e5fc34914f6b (diff)
parent0a8ab17689e628c84a666195bfc6ab85d11cf057 (diff)
Diffstat (limited to 'kernel/rcu/tree.c')
-rw-r--r--kernel/rcu/tree.c20
1 files changed, 14 insertions, 6 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index d1a02877a42c..d0b113de3316 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1718,15 +1718,23 @@ static int rcu_future_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
}
/*
- * Awaken the grace-period kthread for the specified flavor of RCU.
- * Don't do a self-awaken, and don't bother awakening when there is
- * nothing for the grace-period kthread to do (as in several CPUs
- * raced to awaken, and we lost), and finally don't try to awaken
- * a kthread that has not yet been created.
+ * Awaken the grace-period kthread. Don't do a self-awaken (unless in
+ * an interrupt or softirq handler), and don't bother awakening when there
+ * is nothing for the grace-period kthread to do (as in several CPUs raced
+ * to awaken, and we lost), and finally don't try to awaken a kthread that
+ * has not yet been created. If all those checks are passed, track some
+ * debug information and awaken.
+ *
+ * So why do the self-wakeup when in an interrupt or softirq handler
+ * in the grace-period kthread's context? Because the kthread might have
+ * been interrupted just as it was going to sleep, and just after the final
+ * pre-sleep check of the awaken condition. In this case, a wakeup really
+ * is required, and is therefore supplied.
*/
static void rcu_gp_kthread_wake(struct rcu_state *rsp)
{
- if (current == rsp->gp_kthread ||
+ if ((current == rsp->gp_kthread &&
+ !in_interrupt() && !in_serving_softirq()) ||
!READ_ONCE(rsp->gp_flags) ||
!rsp->gp_kthread)
return;