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 <mathias.kretschmer@fokus.fraunhofer.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 5102c3c..b5989c6 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2311,11 +2311,14 @@
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) {
