[PATCH 3.16.y-ckt 135/254] net: skb_fclone_busy() needs to detect orphaned skb

[Luis Henriques]

3.16.7-ckt2 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@xxxxxxxxxx>

commit 39bb5e62867de82b269b07df900165029b928359 upstream.

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@xxxxxxxxxx>
Fixes: 1f3279ae0c13 ("tcp: avoid retransmits of TCP packets hanging in host queues")
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[ luis: backport to 3.16 provided by Eric Dumzet ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 net/ipv4/tcp_output.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 4e4932b5079b..a8794367cd20 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2082,7 +2082,8 @@ static bool skb_still_in_host_queue(const struct sock *sk,
 	const struct sk_buff *fclone = skb + 1;
 
 	if (unlikely(skb->fclone == SKB_FCLONE_ORIG &&
-		     fclone->fclone == SKB_FCLONE_CLONE)) {
+		     fclone->fclone == SKB_FCLONE_CLONE &&
+		     fclone->sk == sk)) {
 		NET_INC_STATS_BH(sock_net(sk),
 				 LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES);
 		return true;
-- 
2.1.0

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