5.4-stable review patch. If anyone has any objections, please let me know.
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From: Yun Lu luyun@kylinos.cn
commit c1ba3c0cbdb5e53a8ec5d708e99cd4c497028a13 upstream.
Due to the changes in commit 581073f626e3 ("af_packet: do not call packet_read_pending() from tpacket_destruct_skb()"), every time tpacket_destruct_skb() is executed, the skb_completion is marked as completed. When wait_for_completion_interruptible_timeout() returns completed, the pending_refcnt has not yet been reduced to zero. Therefore, when ph is NULL, the wait function may need to be called multiple times until packet_read_pending() finally returns zero.
We should call sock_sndtimeo() only once, otherwise the SO_SNDTIMEO constraint could be way off.
Fixes: 581073f626e3 ("af_packet: do not call packet_read_pending() from tpacket_destruct_skb()") Cc: stable@kernel.org Suggested-by: Eric Dumazet edumazet@google.com Signed-off-by: Yun Lu luyun@kylinos.cn Reviewed-by: Eric Dumazet edumazet@google.com Reviewed-by: Willem de Bruijn willemb@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/packet/af_packet.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2713,7 +2713,7 @@ static int tpacket_snd(struct packet_soc int len_sum = 0; int status = TP_STATUS_AVAILABLE; int hlen, tlen, copylen = 0; - long timeo = 0; + long timeo;
mutex_lock(&po->pg_vec_lock);
@@ -2767,6 +2767,7 @@ static int tpacket_snd(struct packet_soc if ((size_max > dev->mtu + reserve + VLAN_HLEN) && !po->has_vnet_hdr) size_max = dev->mtu + reserve + VLAN_HLEN;
+ timeo = sock_sndtimeo(&po->sk, msg->msg_flags & MSG_DONTWAIT); reinit_completion(&po->skb_completion);
do { @@ -2774,7 +2775,6 @@ static int tpacket_snd(struct packet_soc TP_STATUS_SEND_REQUEST); if (unlikely(ph == NULL)) { if (need_wait && skb) { - timeo = sock_sndtimeo(&po->sk, msg->msg_flags & MSG_DONTWAIT); timeo = wait_for_completion_interruptible_timeout(&po->skb_completion, timeo); if (timeo <= 0) { err = !timeo ? -ETIMEDOUT : -ERESTARTSYS;