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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: 7b9eba7ba0 ("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>
alistair/sunxi64-5.4-dsi
Vladimir Oltean 2019-08-30 04:07:21 +03:00 committed by David S. Miller
parent 5f81d54555
commit efb55222d3
1 changed files with 4 additions and 4 deletions
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8
net/sched/sch_taprio.c
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@ -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;