issue: 1181379 Fix TCP zero window probe when there is data in-flight

TCP zero-window probe message should not be sent when there is data in-flight (unacked packets, pcb->unacked != NULL). Signed-off-by: Daniel Libenson <[email protected]>
Mellanox · Nov 13, 2017 · a603f61 · a603f61
1 parent 946cf9c
commit a603f61
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Showing 3 changed files with 5 additions and 7 deletions.
diff --git a/src/vma/lwip/tcp.c b/src/vma/lwip/tcp.c
@@ -728,7 +728,7 @@ tcp_slowtmr(struct tcp_pcb* pcb)
 	  LWIP_DEBUGF(TCP_DEBUG, ("tcp_slowtmr: max DATA retries reached\n"));
 	} else {
 	  if (pcb->persist_backoff > 0) {
-		/* If snd_wnd is zero, use persist timer to send 1 byte probes
+		/* If snd_wnd is zero and pcb->unacked is NULL , use persist timer to send 1 byte probes
 		 * instead of using the standard retransmission mechanism. */
 		pcb->persist_cnt++;
 		if (pcb->persist_cnt >= tcp_persist_backoff[pcb->persist_backoff-1]) {

diff --git a/src/vma/lwip/tcp_in.c b/src/vma/lwip/tcp_in.c
@@ -763,7 +763,7 @@ tcp_receive(struct tcp_pcb *pcb, tcp_in_data* in_data)
       pcb->snd_wl1 = in_data->seqno;
       pcb->snd_wl2 = in_data->ackno;
       if (pcb->snd_wnd == 0) {
-        if (pcb->persist_backoff == 0) {
+        if (pcb->persist_backoff == 0 && pcb->unacked == NULL) {
           /* start persist timer */
           pcb->persist_cnt = 0;
           pcb->persist_backoff = 1;

diff --git a/src/vma/lwip/tcp_out.c b/src/vma/lwip/tcp_out.c
@@ -1564,12 +1564,10 @@ tcp_zero_window_probe(struct tcp_pcb *pcb)
                "   pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n",
                tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
 
-  seg = pcb->unacked;
-
-  if(seg == NULL) {
-    seg = pcb->unsent;
-  }
+  /* Only consider unsent, persist timer should be off when there data is in-flight */
+  seg = pcb->unsent;
   if(seg == NULL) {
+    /* Not expected, persist timer should be off when the send buffer is empty */
     return;
   }