The poll call can return POLLERR which is ignored, or it can return
POLLOUT, even if there are no free frames in the mmap-ed area.
We can account for both of these cases by re-checking if the next
frame is empty before writing into it.
We also now eliminate the timestamp status from the frame status.
Signed-off-by: Mihai Pogonaru <pogonarumi...@gmail.com>
Signed-off-by: Tudor Cornea <tudor.cor...@gmail.com>
---
drivers/net/af_packet/rte_eth_af_packet.c | 47 +++++++++++++++++++++++++++++--
1 file changed, 45 insertions(+), 2 deletions(-)
diff --git a/drivers/net/af_packet/rte_eth_af_packet.c
b/drivers/net/af_packet/rte_eth_af_packet.c
index b73b211..3845df5 100644
--- a/drivers/net/af_packet/rte_eth_af_packet.c
+++ b/drivers/net/af_packet/rte_eth_af_packet.c
@@ -167,6 +167,12 @@ eth_af_packet_rx(void *queue, struct rte_mbuf **bufs,
uint16_t nb_pkts)
return num_rx;
}
+static inline __u32 tx_ring_status_remove_ts(volatile __u32 *tp_status)
+{
+ return *tp_status &
+ ~(TP_STATUS_TS_SOFTWARE | TP_STATUS_TS_RAW_HARDWARE);
+}
+
/*
* Callback to handle sending packets through a real NIC.
*/
@@ -211,9 +217,41 @@ eth_af_packet_tx(void *queue, struct rte_mbuf **bufs,
uint16_t nb_pkts)
}
}
+ /*
+ * We must eliminate the timestamp status from the packet
+ * status. This should only matter if timestamping is enabled
+ * on the socket, but there is a BUG in the kernel which is
+ * fixed in newer releases.
+
+ * For interfaces of type 'veth', the sent skb is forwarded
+ * to the peer and back into the network stack which timestamps
+ * it on the RX path if timestamping is enabled globally
+ * (which happens if any socket enables timestamping).
+
+ * When the skb is destructed, tpacket_destruct_skb() is called
+ * and it calls __packet_set_timestamp() which doesn't check
+ * the flags on the socket and returns the timestamp if it is
+ * set in the skb (and for veth it is, as mentioned above).
+ */
+
/* point at the next incoming frame */
- if ((ppd->tp_status != TP_STATUS_AVAILABLE) &&
- (poll(&pfd, 1, -1) < 0))
+ if ((tx_ring_status_remove_ts(&ppd->tp_status)
+ != TP_STATUS_AVAILABLE) && (poll(&pfd, 1, -1) < 0))
+ break;
+
+ /*
+ * Poll can return POLLERR if the interface is down or POLLOUT,
+ * even if there are no extra buffers available.
+ * This happens, because packet_poll() calls datagram_poll()
+ * which checks the space left in the socket buffer and in the
+ * case of packet_mmap the default socket buffer length
+ * doesn't match the requested size for the tx_ring so there
+ * is always space left in socket buffer, which doesn't seem
+ * to be correlated to the requested size for the tx_ring
+ * in packet_mmap.
+ */
+ if (tx_ring_status_remove_ts(&ppd->tp_status)
+ != TP_STATUS_AVAILABLE)
break;
/* copy the tx frame data */
@@ -242,6 +280,11 @@ eth_af_packet_tx(void *queue, struct rte_mbuf **bufs,
uint16_t nb_pkts)
rte_pktmbuf_free(mbuf);
}
+ /*
+ * We might have to ignore a few more errnos here since the packets
+ * remain in the mmap-ed queue and will be sent later, presumably.
+ */
+
/* kick-off transmits */
if (sendto(pkt_q->sockfd, NULL, 0, MSG_DONTWAIT, NULL, 0) == -1 &&
errno != ENOBUFS && errno != EAGAIN) {
--
2.7.4
