kernel - Fix a case in if_re which could lockup the system

* if_re's re_start function was not always properly setting IFF_OACTIVE
  in situations where packets would be left on the if_snd queue, causing
  if_start_dispatch() to get into an endless message loop.

* Add debugging to device_printf() when the case occurs.

diff --git a/sys/dev/netif/re/if_re.c b/sys/dev/netif/re/if_re.c
index 6231be4..34d7b9a 100644 (file)
--- a/sys/dev/netif/re/if_re.c
+++ b/sys/dev/netif/re/if_re.c
@@ -2468,6 +2468,21 @@ re_start(struct ifnet *ifp)
                ETHER_BPF_MTAP(ifp, m_head);
        }
 
+       /*
+        * If sc->re_ldata.re_tx_mbuf[idx] is not NULL it is possible
+        * for IFF_OACTIVE to not be properly set when we also do not
+        * have sufficient free tx descriptors, leaving packet in
+        * ifp->if_send.  This can cause if_start_dispatch() to loop
+        * infinitely so make sure IFF_OACTIVE is set properly.
+        */
+       if (sc->re_ldata.re_tx_free <= RE_TXDESC_SPARE) {
+               if ((ifp->if_flags & IFF_OACTIVE) == 0) {
+                       device_printf(sc->re_dev,
+                                     "Debug: IFF_OACTIVE was not set when"
+                                     " re_tx_free was below minimum!\n");
+                       ifp->if_flags |= IFF_OACTIVE;
+               }
+       }
        if (!need_trans)
                return;