@@ -947,10 +947,12 @@ static void __tasklet_schedule_common(struct tasklet_struct *t,
* is locked before adding it to the list.
*/
if (test_bit(TASKLET_STATE_SCHED, &t->state)) {
+#if defined(CONFIG_SMP)
if (test_and_set_bit(TASKLET_STATE_CHAINED, &t->state)) {
tasklet_unlock(t);
return;
}
+#endif
t->next = NULL;
*head->tail = t;
head->tail = &(t->next);
@@ -1044,7 +1046,11 @@ static void tasklet_action_common(struct softirq_action *a,
again:
t->func(t->data);
+#if !defined(CONFIG_SMP)
+ while (!tasklet_tryunlock(t)) {
+#else
while (cmpxchg(&t->state, TASKLET_STATEF_RC, 0) != TASKLET_STATEF_RC) {
+#endif
/*
* If it got disabled meanwhile, bail out:
*/
4.19 stable-rt commit 62d0a2a30cd0 (tasklet: Address a race resulting in double-enqueue) addresses a problem that can result in a tasklet being enqueued on two cpus at the same time by combining the RUN flag with a new CHAINED flag, and relies on the combination to be present in order to zero it out, which can never happen on !SMP because the RUN flag is SMP-only. So make sure the above commit is only applied for the SMP case. Signed-off-by: Tom Zanussi <zanussi@kernel.org> --- kernel/softirq.c | 6 ++++++ 1 file changed, 6 insertions(+)