From fbf33a2802f71dba06faa948af805884ff16a2ab Mon Sep 17 00:00:00 2001 From: "Kretschmer, Mathias" Date: Fri, 8 May 2015 15:44:37 +0200 Subject: [PATCH] af_packet / TX_RING not fully non-blocking (w/ MSG_DONTWAIT). This patch fixes an issue where the send(MSG_DONTWAIT) call on a TX_RING is not fully non-blocking in cases where the device's sndBuf is full. We pass nonblock=true to sock_alloc_send_skb() and return any possibly occuring error code (most likely EGAIN) to the caller. As the fast-path stays as it is, we keep the unlikely() around skb == NULL. Signed-off-by: Mathias Kretschmer Signed-off-by: David S. Miller --- net/packet/af_packet.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 5102c3cc4eec..b5989c6ee551 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2311,11 +2311,14 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) tlen = dev->needed_tailroom; skb = sock_alloc_send_skb(&po->sk, hlen + tlen + sizeof(struct sockaddr_ll), - 0, &err); + !need_wait, &err); - if (unlikely(skb == NULL)) + if (unlikely(skb == NULL)) { + /* we assume the socket was initially writeable ... */ + if (likely(len_sum > 0)) + err = len_sum; goto out_status; - + } tp_len = tpacket_fill_skb(po, skb, ph, dev, size_max, proto, addr, hlen); if (tp_len > dev->mtu + dev->hard_header_len) {