From efb55222d31c8c2af8b4ba42bb56b0b0beedf98e Mon Sep 17 00:00:00 2001
From: Vladimir Oltean <olteanv@gmail.com>
Date: Fri, 30 Aug 2019 04:07:21 +0300
Subject: [PATCH] taprio: Fix kernel panic in taprio_destroy
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 matching list_add and list_del better to one another in the
order of operations. This way we can keep the deletion unconditional
and with lower complexity - O(1).
Cc: Leandro Dorileo <leandro.maciel.dorileo@intel.com>
Fixes: 7b9eba7ba0c1 ("net/sched: taprio: fix picos_per_byte miscalculation")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/sched/sch_taprio.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index e25d414ae12fd..8c85f61e98dda 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1249,6 +1249,10 @@ static int taprio_init(struct Qdisc *sch, struct nlattr *opt,
*/
q->clockid = -1;
+ spin_lock(&taprio_list_lock);
+ list_add(&q->taprio_list, &taprio_list);
+ spin_unlock(&taprio_list_lock);
+
if (sch->parent != TC_H_ROOT)
return -EOPNOTSUPP;
@@ -1266,10 +1270,6 @@ static int taprio_init(struct Qdisc *sch, struct nlattr *opt,
if (!opt)
return -EINVAL;
- spin_lock(&taprio_list_lock);
- list_add(&q->taprio_list, &taprio_list);
- spin_unlock(&taprio_list_lock);
-
for (i = 0; i < dev->num_tx_queues; i++) {
struct netdev_queue *dev_queue;
struct Qdisc *qdisc;
--
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