devices: af_packet, fix tx stall by retrying failed sendto

[vpp.git] / src / vnet / devices / af_packet / device.c

diff --git a/src/vnet/devices/af_packet/device.c b/src/vnet/devices/af_packet/device.c
index 1e177f6..e1eb46a 100644 (file)
--- a/src/vnet/devices/af_packet/device.c
+++ b/src/vnet/devices/af_packet/device.c
@@ -418,9 +418,10 @@ VNET_DEVICE_CLASS_TX_FN (af_packet_device_class) (vlib_main_t * vm,
 
   CLIB_MEMORY_BARRIER ();
 
-  if (PREDICT_TRUE (n_sent))
+  if (PREDICT_TRUE (n_sent || tx_queue->is_tx_pending))
     {
       tx_queue->next_tx_frame = tx_frame;
+      tx_queue->is_tx_pending = 0;
 
       if (PREDICT_FALSE (
            sendto (tx_queue->fd, NULL, 0, MSG_DONTWAIT, NULL, 0) == -1))
@@ -429,11 +430,26 @@ VNET_DEVICE_CLASS_TX_FN (af_packet_device_class) (vlib_main_t * vm,
           * Note that we have no reliable way to properly determine the
           * disposition of the packets we just enqueued for delivery.
           */
-         vlib_error_count (vm, node->node_index,
-                           unix_error_is_fatal (errno) ?
-                             AF_PACKET_TX_ERROR_TXRING_FATAL :
-                             AF_PACKET_TX_ERROR_TXRING_EAGAIN,
-                           n_sent);
+         uword counter;
+
+         if (unix_error_is_fatal (errno))
+           {
+             counter = AF_PACKET_TX_ERROR_TXRING_FATAL;
+           }
+         else
+           {
+             counter = AF_PACKET_TX_ERROR_TXRING_EAGAIN;
+             /* non-fatal error: kick again next time
+              * note that you could still end up in a deadlock: if you do not
+              * try to send new packets (ie reschedule this tx node), eg.
+              * because your peer is waiting for the unsent packets to reply
+              * to you but your waiting for its reply etc., you are not going
+              * to kick again, and everybody is waiting for the other to talk
+              * 1st... */
+             tx_queue->is_tx_pending = 1;
+           }
+
+         vlib_error_count (vm, node->node_index, counter, 1);
        }
     }