kern/92948: [patch] em(4) wedges with high traffic

[Mihail Balikov]

>Number:         92948
>Category:       kern
>Synopsis:       [patch] em(4) wedges with high traffic
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Feb 07 07:50:03 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator:     Mihail Balikov
>Release:        7.0-Current
>Organization:
>Environment:
FreeBSD curr 7.0-CURRENT FreeBSD 7.0-CURRENT #0: Sat Dec 17 11:36:50 EET 2005 root at curr:/usr/obj/usr/src/sys/joiner i386
>Description:
Interface watchdog fires, if tx descriptor ring is not emptied for EM_TX_TIMEOUT seconds.
              
>How-To-Repeat:
              
>Fix:
Following comments in em(4) code, watchdog timer should be restarted if we process some descriptors, but current code restarts timer if no descriptors are freed (num_avail == adapter->num_tx_desc_avail)
 
  * If there are no pending descriptors, clear the timeout. Otherwise,
  * if some descriptors have been freed, restart the timeout.

It seems to be "typo" bug, this patch fixes problem for me

--- em.060207.diff begins here ---
--- if_em.c Wed Feb  1 19:42:55 2006
+++ if_em.c.new Tue Feb  7 08:43:03 2006
@@ -2744,7 +2744,7 @@
                 ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
                 if (num_avail == adapter->num_tx_desc)
                         ifp->if_timer = 0;
-                else if (num_avail == adapter->num_tx_desc_avail)
+                else if (num_avail != adapter->num_tx_desc_avail)
                         ifp->if_timer = EM_TX_TIMEOUT;
         }
         adapter->num_tx_desc_avail = num_avail;
--- em.060207.diff ends here ---


  
>Release-Note:
>Audit-Trail:
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