[PATCH net 1/3] taprio: Fix kernel panic in taprio_destroy

[Vladimir Oltean]

taprio_init may fail earlier than this line:

        list_add(&q->taprio_list, &taprio_list);

i.e. due to the net device not being multi queue.

Attempting to remove q from the global taprio_list when it is not part
of it will result in a kernel panic.

Fix it by iterating through the list and removing it only if found.

Signed-off-by: Vladimir Oltean <olte...@gmail.com>
---
 net/sched/sch_taprio.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 540bde009ea5..f1eea8c68011 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1199,12 +1199,17 @@ static int taprio_change(struct Qdisc *sch, struct 
nlattr *opt,
 
 static void taprio_destroy(struct Qdisc *sch)
 {
-       struct taprio_sched *q = qdisc_priv(sch);
+       struct taprio_sched *p, *q = qdisc_priv(sch);
        struct net_device *dev = qdisc_dev(sch);
+       struct list_head *pos, *tmp;
        unsigned int i;
 
        spin_lock(&taprio_list_lock);
-       list_del(&q->taprio_list);
+       list_for_each_safe(pos, tmp, &taprio_list) {
+               p = list_entry(pos, struct taprio_sched, taprio_list);
+               if (p == q)
+                       list_del(&q->taprio_list);
+       }
        spin_unlock(&taprio_list_lock);
 
        hrtimer_cancel(&q->advance_timer);
-- 
2.17.1