[patch-rt] hotplug, hrtimer: Migrate expired/deferred timers during cpu offline

From: Mike Galbraith
Date: Fri Aug 11 2017 - 03:55:38 EST


The below fixes the list debug explosion up.

If we do not migrate expired/deferred timers during cpu offline, ->cb_entry
will be corrupted by online initialization of base->expired, leading to a
loud list debug complaint should someone call __remove_hrtimer() thereafter.

Signed-off-by: Mike Galvraith <efault@xxxxxx>
---
kernel/time/hrtimer.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1802,6 +1802,19 @@ static void migrate_hrtimer_list(struct
*/
enqueue_hrtimer(timer, new_base);
}
+
+ /*
+ * Finally, migrate any expired timers deferred by RT.
+ */
+ while (!list_empty(&old_base->expired)) {
+ struct list_head *entry = old_base->expired.next;
+
+ timer = container_of(entry, struct hrtimer, cb_entry);
+ /* XXX: hm, perhaps defer again instead of enqueueing. */
+ __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
+ timer->base = new_base;
+ enqueue_hrtimer(timer, new_base);
+ }
}

int hrtimers_dead_cpu(unsigned int scpu)