This is a note to let you know that I've just added the patch titled
net: sched: do not requeue a NULL skb
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-sched-do-not-requeue-a-null-skb.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon May 16 11:21:32 PDT 2016
From: Lars Persson <lars.persson@xxxxxxxx>
Date: Tue, 12 Apr 2016 08:45:52 +0200
Subject: net: sched: do not requeue a NULL skb
From: Lars Persson <lars.persson@xxxxxxxx>
[ Upstream commit 3dcd493fbebfd631913df6e2773cc295d3bf7d22 ]
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.
We take the optimistic approach and continue running the queue after a
failure since it is unknown if later packets also will fail in the
validate path.
Fixes: 55a93b3ea780 ("qdisc: validate skb without holding lock")
Signed-off-by: Lars Persson <larper@xxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/sch_generic.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -159,12 +159,15 @@ int sch_direct_xmit(struct sk_buff *skb,
if (validate)
skb = validate_xmit_skb_list(skb, dev);
- if (skb) {
+ if (likely(skb)) {
HARD_TX_LOCK(dev, txq, smp_processor_id());
if (!netif_xmit_frozen_or_stopped(txq))
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);
Patches currently in stable-queue which might be from lars.persson@xxxxxxxx are
queue-4.4/net-sched-do-not-requeue-a-null-skb.patch
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