PERFORCE change 111204 for review

[Marko Zec]

http://perforce.freebsd.org/chv.cgi?CH=111204

Change 111204 by zec at zec_tca51 on 2006/12/06 17:41:53

	At creation time assign each vnet a unique positive integer id.
	The only use for this id so far is to serve as an index into
	vnetb_tbl[], which stores ptrs to all corresponding vnets.
	The table indexing method of fetching the appropriate vnet * is
	used only in tcp timer-triggered functions as an interim hack.
	In those function it is possible for (struct tcpcb *tp)->t_inpcb
	to be NULL due to some race conditions that I do not comprehend,
	but which are documented and handled in the existing code.  Given
	that in timer-triggered functions curvnetb is always NULL, and
	that we cannot reliably fetch vnet * from tp->t_inpcb->inp_vnet,
	as an alternative method we fetch vnet * from
	vnetb_tbl[tp->vnet_id].
	
	NB this whole hassle of going through a table to fetch a ptr
	to a vnet could be easily avoided if we stored the ptr directly
	in the struct tcpcb.  However, doing so would alter the size
	of tcpcb and I would have to rebuild my userland as a consequence.
	OTOH struct tcpcb has enough spare room for a 16-bit index...
	
	Hope nobody is actually reading this...

Affected files ...

.. //depot/projects/vimage/src/sys/kern/kern_vimage.c#7 edit
.. //depot/projects/vimage/src/sys/netinet/tcp_subr.c#4 edit
.. //depot/projects/vimage/src/sys/netinet/tcp_timer.c#4 edit
.. //depot/projects/vimage/src/sys/sys/vimage.h#6 edit

Differences ...

==== //depot/projects/vimage/src/sys/kern/kern_vimage.c#7 (text+ko) ====

@@ -402,6 +402,7 @@
         struct vprocg *vprocg;
         struct vcpu *vcpu;
 	struct domain *dp;
+	int i;
 
 printf("vi_alloc: %s\n", name);
 	/* A brute force check whether there's enough mem for a new vimage */
@@ -421,6 +422,12 @@
         bzero(vnetb, sizeof(struct vnet_base));
 	vip->v_vnetb = vnetb;
 	vnetb->vnet_magic_n = VNET_MAGIC_N;
+	for (i = 0; i < 100; i++)	/* XXX !!! */
+		if (vnetb_tbl[i] == NULL) {
+			vnetb->vnet_id = i;
+			vnetb_tbl[i] = vnetb;
+			break;
+		}
 
         vprocg = malloc(sizeof(struct vprocg), M_VPROCG, M_NOWAIT);
         if (vprocg == NULL)
@@ -555,7 +562,9 @@
 	vimage_0.v_procg = &vprocg_0;
 	vimage_0.v_cpu = &vcpu_0;
 
-	vnetb_tbl[0] = &vnetb_0;	/* XXX */
+	vnetb_0.vnet_id = 1;			/* XXX */
+	vnetb_tbl[0] = (void *) 0xc0dedead;	/* XXX */
+	vnetb_tbl[1] = &vnetb_0;		/* XXX */
 	vnetb_0.vnet_magic_n = VNET_MAGIC_N;
 
 	TAILQ_INIT(&vnet_modlink_head);

==== //depot/projects/vimage/src/sys/netinet/tcp_subr.c#4 (text+ko) ====

@@ -684,6 +684,9 @@
 	if (tm == NULL)
 		return (NULL);
 	tp = &tm->tcb;
+#ifdef VIMAGE
+	tp->vnet_id = inp->inp_vnetb->vnet_id;
+#endif
 	/*	LIST_INIT(&tp->t_segq); */	/* XXX covered by M_ZERO */
 	tp->t_maxseg = tp->t_maxopd =
 #ifdef INET6

==== //depot/projects/vimage/src/sys/netinet/tcp_timer.c#4 (text+ko) ====


==== //depot/projects/vimage/src/sys/sys/vimage.h#6 (text+ko) ====

@@ -83,6 +83,8 @@
         int     ifccnt;
         int     sockcnt;
 
+	int	vnet_id;	/* index to vnetb_tbl */
+
 	int	vnet_magic_n;
 };