* [PATCH net] net: sched: do not requeue a NULL skb
@ 2016-04-06 13:10 Lars Persson
2016-04-06 17:14 ` Cong Wang
0 siblings, 1 reply; 2+ messages in thread
From: Lars Persson @ 2016-04-06 13:10 UTC (permalink / raw)
To: netdev; +Cc: jhs, linux-kernel, Lars Persson
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.
Fixes: 55a93b3ea780 ("qdisc: validate skb without holding lock")
Signed-off-by: Lars Persson <larper@axis.com>
---
net/sched/sch_generic.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index f18c350..1031536 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -165,6 +165,9 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
skb = dev_hard_start_xmit(skb, dev, txq, &ret);
HARD_TX_UNLOCK(dev, txq);
+ } else {
+ spin_lock(root_lock);
+ return qdisc_qlen(q);
}
spin_lock(root_lock);
--
2.1.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] net: sched: do not requeue a NULL skb
2016-04-06 13:10 [PATCH net] net: sched: do not requeue a NULL skb Lars Persson
@ 2016-04-06 17:14 ` Cong Wang
0 siblings, 0 replies; 2+ messages in thread
From: Cong Wang @ 2016-04-06 17:14 UTC (permalink / raw)
To: Lars Persson
Cc: Linux Kernel Network Developers, Jamal Hadi Salim, LKML,
Lars Persson
On Wed, Apr 6, 2016 at 6:10 AM, Lars Persson <lars.persson@axis.com> 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.
>
Sounds reasonable.
> Fixes: 55a93b3ea780 ("qdisc: validate skb without holding lock")
> Signed-off-by: Lars Persson <larper@axis.com>
> ---
> net/sched/sch_generic.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
> index f18c350..1031536 100644
> --- a/net/sched/sch_generic.c
> +++ b/net/sched/sch_generic.c
> @@ -165,6 +165,9 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
> skb = dev_hard_start_xmit(skb, dev, txq, &ret);
>
> HARD_TX_UNLOCK(dev, txq);
> + } else {
> + spin_lock(root_lock);
> + return qdisc_qlen(q);
I think we should return 0 for this failure case so that qdisc_restart()
will stop. How about teaching dev_requeue_skb() to skip skb==NULL
case?
^ permalink raw reply [flat|nested] 2+ messages in thread
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