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net: skb_fclone_busy() needs to detect orphaned skb

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Some drivers are unable to perform TX completions in a bound time.
They instead call skb_orphan()

Problem is skb_fclone_busy() has to detect this case, otherwise
we block TCP retransmits and can freeze unlucky tcp sessions on
mostly idle hosts.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 1f3279ae0c ("tcp: avoid retransmits of TCP packets hanging in host queues")
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2014-10-30 10:32:34 -07:00 committed by David S. Miller
parent 14051f0452
commit 39bb5e6286
3 changed files with 8 additions and 4 deletions
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8
include/linux/skbuff.h
View file

@ -799,15 +799,19 @@ struct sk_buff_fclones {
* @skb: buffer
*
* Returns true is skb is a fast clone, and its clone is not freed.
* Some drivers call skb_orphan() in their ndo_start_xmit(),
* so we also check that this didnt happen.
*/
static inline bool skb_fclone_busy(const struct sk_buff *skb)
static inline bool skb_fclone_busy(const struct sock *sk,
const struct sk_buff *skb)
{
const struct sk_buff_fclones *fclones;
fclones = container_of(skb, struct sk_buff_fclones, skb1);
return skb->fclone == SKB_FCLONE_ORIG &&
fclones->skb2.fclone == SKB_FCLONE_CLONE;
fclones->skb2.fclone == SKB_FCLONE_CLONE &&
fclones->skb2.sk == sk;
}
static inline struct sk_buff *alloc_skb_fclone(unsigned int size,

2
net/ipv4/tcp_output.c
View file

@ -2126,7 +2126,7 @@ bool tcp_schedule_loss_probe(struct sock *sk)
static bool skb_still_in_host_queue(const struct sock *sk,
const struct sk_buff *skb)
{
if (unlikely(skb_fclone_busy(skb))) {
if (unlikely(skb_fclone_busy(sk, skb))) {
NET_INC_STATS_BH(sock_net(sk),
LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES);
return true;

2
net/xfrm/xfrm_policy.c
View file

@ -1962,7 +1962,7 @@ static int xdst_queue_output(struct sock *sk, struct sk_buff *skb)
struct xfrm_policy *pol = xdst->pols[0];
struct xfrm_policy_queue *pq = &pol->polq;
if (unlikely(skb_fclone_busy(skb))) {
if (unlikely(skb_fclone_busy(sk, skb))) {
kfree_skb(skb);
return 0;
}