PERFORCE change 160461 for review

[Marko Zec]

http://perforce.freebsd.org/chv.cgi?CH=160461

Change 160461 by zec at zec_tpx32 on 2009/04/10 20:41:17

	       Merge from vimage branch an explicit check for circular (or for
	       any reason unresolved) dependencies between vnet modules.  This
	       check, scheduled right before the kernel going multiuser, looks
	       at the vinet_modpending TAILQ for any pending vnet modules,
	       prints them out, and panics.
	
	       The effectivenes of this check can be easily demonstrated by
	       say adding a dependency on INET6 to INET, while INET6 is already
	       depending on INET, so none of them would ever get registered.
	
	       bz suggested that we might wish to commit this as a separate 
	       patch, but I'm inclined to proclaim this check to be an integral
	       and essential part of the vnet_mod_registration framework, though 
	       it doesn't help with checking for unresolved vnet_mod dependencies
	       for modules kldloaded after system initialization is complete.
	
	       While here, attempt to improve consistency and verbosity of a
	       few comments and debugging printf-s.

Affected files ...

.. //depot/projects/vimage-commit2/src/sys/kern/kern_vimage.c#13 edit
.. //depot/projects/vimage-commit2/src/sys/sys/kernel.h#7 edit

Differences ...

==== //depot/projects/vimage-commit2/src/sys/kern/kern_vimage.c#13 (text+ko) ====

@@ -61,32 +61,40 @@
 {
 	struct vnet_modlink *vml, *vml_iter;
 	
-	/* Do not register the same module instance more than once. */
+	/* Do not register the same {module, iarg} pair more than once. */
 	TAILQ_FOREACH(vml_iter, &vnet_modlink_head, vml_mod_le)
 		if (vml_iter->vml_modinfo == vmi && vml_iter->vml_iarg == iarg)
 			break;
 	if (vml_iter != NULL)
-		panic("attempt to register an already registered vnet module");
+		panic("registering an already registered vnet module: %s",
+		    vml_iter->vml_modinfo->vmi_name);
 	vml = malloc(sizeof(struct vnet_modlink), M_VIMAGE, M_NOWAIT);
 
 	/*
 	 * XXX we support only statically assigned module IDs at the time.
 	 * In principle modules should be able to get a dynamically
 	 * assigned ID at registration time.
+	 *
+	 * If a module is registered in multiple instances, then each
+	 * instance must have both iarg and iname set.
 	 */
-	VNET_ASSERT(vmi->vmi_id > 0 || vmi->vmi_id < VNET_MOD_MAX);
-	VNET_ASSERT(!((iarg == NULL) ^ (iname == NULL)));
+	if (vmi->vmi_id >= VNET_MOD_MAX)
+		panic("invalid vnet module ID: %d", vmi->vmi_id);
+	if (vmi->vmi_name == NULL)
+		panic("vnet module with no name: %d", vmi->vmi_id);
+	if ((iarg == NULL) ^ (iname == NULL))
+		panic("invalid vnet module instance: %s", vmi->vmi_name);
 
 	vml->vml_modinfo = vmi;
 	vml->vml_iarg = iarg;
 	vml->vml_iname = iname;
 
-	/* Check whether the module we depend on is already registered */
+	/* Check whether the module we depend on is already registered. */
 	if (vmi->vmi_dependson != vmi->vmi_id) {
 		TAILQ_FOREACH(vml_iter, &vnet_modlink_head, vml_mod_le)
 			if (vml_iter->vml_modinfo->vmi_id ==
 			    vmi->vmi_dependson)
-				break;	/* Depencency found, we are done */
+				break;	/* Depencency found, we are done. */
 		if (vml_iter == NULL) {
 #ifdef DEBUG_ORDERING
 			printf("dependency %d missing for vnet mod %s,"
@@ -116,7 +124,7 @@
 		CURVNET_RESTORE();
 	}
 
-	/* Check for pending modules depending on us */
+	/* Check for pending modules depending on us. */
 	do {
 		TAILQ_FOREACH(vml_iter, &vnet_modpending_head, vml_mod_le)
 			if (vml_iter->vml_modinfo->vmi_dependson ==
@@ -141,7 +149,7 @@
 	const struct vnet_modinfo *vmi = vml->vml_modinfo;
 
 #ifdef DEBUG_ORDERING
-	printf("instatiating vnet_%s", vmi->vmi_name);
+	printf("instantiating vnet_%s", vmi->vmi_name);
 	if (vml->vml_iarg)
 		printf("/%s", vml->vml_iname);
 	printf(": ");
@@ -156,7 +164,7 @@
 	if (vmi->vmi_struct_size) {
 		void *mem = malloc(vmi->vmi_struct_size, M_VNET,
 		    M_NOWAIT | M_ZERO);
-		if (mem == NULL) /* XXX should return error, not panic */
+		if (mem == NULL) /* XXX should return error, not panic. */
 			panic("vi_alloc: malloc for %s\n", vmi->vmi_name);
 		curvnet->mod_data[vmi->vmi_id] = mem;
 	}
@@ -200,8 +208,27 @@
 {
 
 	TAILQ_INIT(&vnet_modlink_head);
+	TAILQ_INIT(&vnet_modpending_head);
+}
+
+static void
+vi_init_done(void *unused)
+{
+	struct vnet_modlink *vml_iter;
+
+	if (TAILQ_EMPTY(&vnet_modpending_head))
+		return;
+
+	printf("vnet modules with unresolved dependencies:\n");
+	TAILQ_FOREACH(vml_iter, &vnet_modpending_head, vml_mod_le)
+		printf("    %d:%s depending on %d\n",
+		    vml_iter->vml_modinfo->vmi_id,
+		    vml_iter->vml_modinfo->vmi_name,
+		    vml_iter->vml_modinfo->vmi_dependson);
+	panic("going nowhere without my vnet modules!");
 }
 
 SYSINIT(vimage, SI_SUB_VIMAGE, SI_ORDER_FIRST, vi_init, NULL);
+SYSINIT(vimage_done, SI_SUB_VIMAGE_DONE, SI_ORDER_FIRST, vi_init_done, NULL);
 
 #endif /* !VIMAGE_GLOBALS */

==== //depot/projects/vimage-commit2/src/sys/sys/kernel.h#7 (text+ko) ====

@@ -163,6 +163,7 @@
 	SI_SUB_SWAP		= 0xc000000,	/* swap */
 	SI_SUB_INTRINSIC_POST	= 0xd000000,	/* proc 0 cleanup*/
 	SI_SUB_SYSCALLS		= 0xd800000,	/* register system calls */
+	SI_SUB_VIMAGE_DONE	= 0xdc00000,	/* vnet registration complete */
 	SI_SUB_KTHREAD_INIT	= 0xe000000,	/* init process*/
 	SI_SUB_KTHREAD_PAGE	= 0xe400000,	/* pageout daemon*/
 	SI_SUB_KTHREAD_VM	= 0xe800000,	/* vm daemon*/