kern/128577: [patch] Send queue stall in ixgbe driver when MSIX interrups are used

[Dmitry Tejblum]

>Number:         128577
>Category:       kern
>Synopsis:       [patch] Send queue stall in ixgbe driver when MSIX interrups are used
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Nov 04 10:10:01 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Dmitry Tejblum
>Release:        FreeBSD 7.1-PRERELEASE i386
>Organization:
>Environment:
FreeBSD 7.1-PRERELEASE 


>Description:

A call of ixgbe_start_locked() is missed in ixgbe_msix_tx -- the TX interrupt
handler when MSIX interrupts are used.

(It sometime cause sending stall: when if_snd queue is full, the upper layer 
does not call if_start entry point, so if TX interrupt does not send some
packets and does not free some space in the if_snd queue, nothing will ever be
sent. Other TX handlers call ixgbe_start_locked().)

>How-To-Repeat:

>Fix:


--- ixgbe.c	2008-08-12 01:02:22.000000000 +0400
+++ ixgbe.c	2008-11-04 12:40:46.000000000 +0300
@@ -1056,6 +1056,7 @@ ixgbe_msix_tx(void *arg)
 	while (loop++ < MAX_INTR)
 		if (ixgbe_txeof(txr) == 0)
 			break;
+	ixgbe_start_locked(txr, adapter->ifp);
 	IXGBE_TX_UNLOCK(txr);
 	/* Reenable this interrupt */
 	IXGBE_WRITE_REG(&adapter->hw, IXGBE_EIMS, txr->eims);
>Release-Note:
>Audit-Trail:
>Unformatted: