Re: [PATCH net 1/3] taprio: Fix kernel panic in taprio_destroy
From: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Date: 2019-08-28 16:31:06
Hi, Vladimir Oltean [off-list ref] writes:
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.
Good catch.
quoted hunk ↗ jump to hunk
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 <olteanv@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); + }
Personally, I would do things differently, I am thinking: adding the taprio instance earlier to the list in taprio_init(), and keeping taprio_destroy() the way it is now. But take this more as a suggestion :-) Cheers, -- Vinicius