Re: [RFC][PATCH 03/16] sched: Wrap rq::lock access

Julien Desfossez
2019-03-18T15:42:12Z

The case where we try to acquire the lock on 2 runqueues belonging to 2
different cores requires the rq_lockp wrapper as well otherwise we
frequently deadlock in there.

This fixes the crash reported in
1552577311-8218-1-git-send-email-jdesfossez@digitalocean.com

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 76fee56..71bb71f 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2078,7 +2078,7 @@ static inline void double_rq_lock(struct rq *rq1, struct rq *rq2)
raw_spin_lock(rq_lockp(rq1));
__acquire(rq2->lock); /* Fake it out ;) */
} else {
- if (rq1 < rq2) {
+ if (rq_lockp(rq1) < rq_lockp(rq2)) {
raw_spin_lock(rq_lockp(rq1));
raw_spin_lock_nested(rq_lockp(rq2), SINGLE_DEPTH_NESTING);
} else {
--
2.7.4