From davidcs at FreeBSD.org  Tue Apr  7 18:14:02 2015
From: davidcs at FreeBSD.org (David C Somayajulu)
Date: Tue, 7 Apr 2015 18:14:02 +0000 (UTC)
Subject: svn commit: r281219 - stable/7/sys/dev/bxe
Message-ID: <201504071814.t37IE2qb069676@svn.freebsd.org>

Author: davidcs
Date: Tue Apr  7 18:14:01 2015
New Revision: 281219
URL: https://svnweb.freebsd.org/changeset/base/281219

Log:
  MFC r281006
  When an mbuf allocation fails in the receive path, the mbuf containing the received packet is not sent to the host network stack and is reused again on the receive ring.  Remaining received packets in the ring are not processed in that invocation of bxe_rxeof() and defered to the task thread

Modified:
  stable/7/sys/dev/bxe/bxe.c
Directory Properties:
  stable/7/sys/   (props changed)

Modified: stable/7/sys/dev/bxe/bxe.c
==============================================================================
--- stable/7/sys/dev/bxe/bxe.c	Tue Apr  7 18:10:58 2015	(r281218)
+++ stable/7/sys/dev/bxe/bxe.c	Tue Apr  7 18:14:01 2015	(r281219)
@@ -3257,7 +3257,7 @@ bxe_rxeof(struct bxe_softc    *sc,
     uint16_t bd_cons, bd_prod, bd_prod_fw, comp_ring_cons;
     uint16_t hw_cq_cons, sw_cq_cons, sw_cq_prod;
     int rx_pkts = 0;
-    int rc;
+    int rc = 0;
 
     BXE_FP_RX_LOCK(fp);
 
@@ -3399,6 +3399,10 @@ bxe_rxeof(struct bxe_softc    *sc,
                                   (sc->max_rx_bufs != RX_BD_USABLE) ?
                                       bd_prod : bd_cons);
         if (rc != 0) {
+
+            /* we simply reuse the received mbuf and don't post it to the stack */
+            m = NULL;
+
             BLOGE(sc, "mbuf alloc fail for fp[%02d] rx chain (%d)\n",
                   fp->index, rc);
             fp->eth_q_stats.rx_soft_errors++;
@@ -3487,6 +3491,9 @@ next_cqe:
         sw_cq_cons = RCQ_NEXT(sw_cq_cons);
 
         /* limit spinning on the queue */
+        if (rc != 0)
+            break;
+
         if (rx_pkts == sc->rx_budget) {
             fp->eth_q_stats.rx_budget_reached++;
             break;