Re: em driver issues

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

:>    Well, that was an easy fix.  I've committed a fix, please continue
:>    to try to crash the box with packets!
:>
:>    The patch is enclosed
:
:The patch didn't fix the problem. However with a bit of digging, it seems that
:this particular crash can be stopped with:

    Ach.  You are right.  I have to move the NULL check down a level.  I'll
    commit another patch.  In fact, there is another second of code in the
    same file which does it eactly the way you indicate below.

:However it seems that if mcl == NULL && how != MB_WAIT then there is
:no point in trying to allocate data, so the routine should fail there. Also 
:the
:case where mcl == NULL, how != MB_WAIT tries to use the null mcl if
:data is successfully allocated. I think that something like the 
:following seems needed:
:
:if (mcl == NULL){
:   if (how != MB_WAIT)
:      break;
:   mbstat.m_wait++;
:   mcl = malloc(sizeof(*mcl),M_MBUFCL, M_WAITOK|M_NULLOK|M_ZERO);
:   if (mcl == NULL){
:      break;
:   }
:}
:
:hopefully this is clear.
:
:EM

    Ok, here is another patch.

					-Matt
					Matthew Dillon 
					<dillon@xxxxxxxxxxxxx>

Index: uipc_mbuf.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_mbuf.c,v
retrieving revision 1.30
diff -u -r1.30 uipc_mbuf.c
--- uipc_mbuf.c	4 Feb 2005 01:14:27 -0000	1.30
+++ uipc_mbuf.c	4 Feb 2005 19:11:06 -0000
@@ -82,7 +82,7 @@
  *
  * @(#)uipc_mbuf.c	8.2 (Berkeley) 1/4/94
  * $FreeBSD: src/sys/kern/uipc_mbuf.c,v 1.51.2.24 2003/04/15 06:59:29 silby Exp $
- * $DragonFly: src/sys/kern/uipc_mbuf.c,v 1.30 2005/02/04 01:14:27 dillon Exp $
+ * $DragonFly$
  */
 
 #include "opt_param.h"
@@ -424,10 +424,12 @@
 		 * Meta structure
 		 */
 		mcl = malloc(sizeof(*mcl), M_MBUFCL, M_NOWAIT|M_NULLOK|M_ZERO);
-		if (mcl == NULL && how == MB_WAIT) {
-			mbstat.m_wait++;
-			mcl = malloc(sizeof(*mcl), 
-					M_MBUFCL, M_WAITOK|M_NULLOK|M_ZERO);
+		if (mcl == NULL) {
+			if (how == MB_WAIT) {
+				mbstat.m_wait++;
+				mcl = malloc(sizeof(*mcl), 
+					    M_MBUFCL, M_WAITOK|M_NULLOK|M_ZERO);
+			}
 			if (mcl == NULL)
 				break;
 		}