On 04/11/2016 03:23 PM, Eric Dumazet wrote:
On Mon, 2016-04-11 at 08:24 +0200, Lars Persson wrote:
A failure in validate_xmit_skb_list() triggered an unconditional call
to dev_requeue_skb with skb=NULL. This slowly grows the queue
discipline's qlen count until all traffic through the queue stops.
By introducing a NULL check in dev_requeue_skb it was also necessary
to make the __netif_schedule call conditional to avoid scheduling an
empty queue.
Fixes: 55a93b3ea780 ("qdisc: validate skb without holding lock")
Signed-off-by: Lars Persson <lar...@axis.com>
---
net/sched/sch_generic.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index f18c350..4e6a79c 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -47,10 +47,13 @@ EXPORT_SYMBOL(default_qdisc_ops);
static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
{
- q->gso_skb = skb;
- q->qstats.requeues++;
- q->q.qlen++; /* it's still part of the queue */
- __netif_schedule(q);
+ if (skb) {
+ q->gso_skb = skb;
+ q->qstats.requeues++;
+ q->q.qlen++; /* it's still part of the queue */
+ }
+ if (qdisc_qlen(q))
+ __netif_schedule(q);
return 0;
}
Please always CC patch author when fixing a bug.
Why adding the if (qdisc_qlen(q)) extra test ?
This seems unrelated to the bug fix, and probably should be part of a
second patch targeting net-next tree.
I though it would be prudent because the queue can be non-empty even for
the case of skb=NULL. So should it be there in this patch, another patch
or not at all ?
Also please add a likely() clause
if (likely(skb)) {
q->gso_skb = skb;
q->qstats.requeues++;
q->q.qlen++; /* it's still part of the queue */
__netif_schedule(q);
}
Will fix.
Thanks !
