Proposed module init race fix.

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .17886-linux-2.5-bk/drivers/block/genhd.c .17886-linux-2.5-bk.updated/drivers/block/genhd.c
@@ -104,10 +104,13 @@ static int exact_lock(dev_t dev, void *d
  * @gp: per-device partitioning information
  *
  * This function registers the partitioning information in @gp
- * with the kernel.
+ * with the kernel.  Your init function MUST NOT FAIL after this.
  */
 void add_disk(struct gendisk *disk)
 {
+	/* It needs to be accessible so we can read partitions. */
+	make_module_live(disk->fops->owner);
+
 	disk->flags |= GENHD_FL_UP;
 	blk_register_region(MKDEV(disk->major, disk->first_minor), disk->minors,
 			NULL, exact_match, exact_lock, disk);

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .17886-linux-2.5-bk/include/linux/module.h .17886-linux-2.5-bk.updated/include/linux/module.h
@@ -49,6 +49,11 @@ search_extable(const struct exception_ta
 	       const struct exception_table_entry *last,
 	       unsigned long value);
 
+/* Want to know when a module (or kernel) is finally made live? */
+extern int module_notifier_register(struct notifier_block *n);
+extern void module_notifier_unregister(struct notifier_block *n);
+extern void module_live_notify(struct module *module);
+
 #ifdef MODULE
 
 /* For replacement modutils, use an alias not a pointer. */

@@ -230,12 +235,9 @@ struct module
 	char *args;
 };
 
-/* FIXME: It'd be nice to isolate modules during init, too, so they
-   aren't used before they (may) fail.  But presently too much code
-   (IDE & SCSI) require entry into the module during init.*/
 static inline int module_is_live(struct module *mod)
 {
-	return mod->state != MODULE_STATE_GOING;
+	return mod->state == MODULE_STATE_LIVE;
 }
 
 /* Is this address in a module? */

@@ -261,8 +263,11 @@ static inline int try_module_get(struct 
 		unsigned int cpu = get_cpu();
 		if (likely(module_is_live(module)))
 			local_inc(&module->ref[cpu].count);
-		else
+		else {
+			/* This is possible, but most likely it's reentry. */
+			WARN_ON(module->state == MODULE_STATE_COMING);
 			ret = 0;
+		}
 		put_cpu();
 	}
 	return ret;

@@ -300,6 +305,12 @@ static inline void module_put(struct mod
 	__mod ? __mod->name : "kernel";		\
 })
 
+static inline void module_make_live(struct module *module)
+{
+	if (module)
+		module->state = MODULE_STATE_LIVE;
+}
+
 #define __unsafe(mod)							     \
 do {									     \
 	if (mod && !(mod)->unsafe) {					     \

@@ -353,6 +364,8 @@ static inline void module_put(struct mod
 
 #define module_name(mod) "kernel"
 
+#define module_make_live(mod)
+
 #define __unsafe(mod)
 
 /* For kallsyms to ask for address resolution.  NULL means not found. */

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .17886-linux-2.5-bk/include/linux/notifier.h .17886-linux-2.5-bk.updated/include/linux/notifier.h
@@ -66,5 +66,6 @@ extern int notifier_call_chain(struct no
 #define CPU_OFFLINE	0x0005 /* CPU (unsigned)v offline (still scheduling) */
 #define CPU_DEAD	0x0006 /* CPU (unsigned)v dead */
 
+#define MODULE_LIVE	0x0001 /* Module (struct module *)v is live */
 #endif /* __KERNEL__ */
 #endif /* _LINUX_NOTIFIER_H */

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .17886-linux-2.5-bk/init/main.c .17886-linux-2.5-bk.updated/init/main.c
@@ -359,6 +359,24 @@ static void rest_init(void)
  	cpu_idle();
 } 
 
+static struct notifier_block *module_notifier;
+
+/* Want to know when a module (or kernel) is finally made live? */
+int module_notifier_register(struct notifier_block *n)
+{
+	return notifier_chain_register(&module_notifier, n);
+}
+
+void module_notifier_unregister(struct notifier_block *n)
+{
+	notifier_chain_unregister(n);
+}
+
+void module_live_notify(struct module *module)
+{
+	notifier_call_chain(module_notifier, MODULE_LIVE, module);
+}
+
 /*
  *	Activate the first processor.
  */

@@ -465,6 +483,8 @@ static void __init do_initcalls(void)
 
 	/* Make sure there is no pending stuff from the initcall sequence */
 	flush_scheduled_work();
+
+	module_live_notify(NULL);
 }
 
 /*

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .17886-linux-2.5-bk/kernel/module.c .17886-linux-2.5-bk.updated/kernel/module.c
@@ -60,14 +60,6 @@ static LIST_HEAD(modules);
 static LIST_HEAD(symbols);
 static LIST_HEAD(extables);
 
-/* We require a truly strong try_module_get() */
-static inline int strong_try_module_get(struct module *mod)
-{
-	if (mod && mod->state == MODULE_STATE_COMING)
-		return 0;
-	return try_module_get(mod);
-}
-
 /* Stub function for modules which don't have an initfn */
 int init_module(void)
 {

@@ -562,7 +554,7 @@ static inline void module_unload_free(st
 
 static inline int use_module(struct module *a, struct module *b)
 {
-	return strong_try_module_get(b);
+	return try_module_get(b);
 }
 
 static inline void module_unload_init(struct module *mod)

@@ -779,7 +771,7 @@ void *__symbol_get(const char *symbol)
 
 	spin_lock_irqsave(&modlist_lock, flags);
 	value = __find_symbol(symbol, &ksg, 1);
-	if (value && !strong_try_module_get(ksg->owner))
+	if (value && !try_module_get(ksg->owner))
 		value = 0;
 	spin_unlock_irqrestore(&modlist_lock, flags);
 

@@ -1285,7 +1277,7 @@ sys_init_module(void *umod,
 			   (unsigned long)mod->module_core + mod->core_size);
 
 	/* Now sew it into the lists.  They won't access us, since
-           strong_try_module_get() will fail. */
+           try_module_get() will fail. */
 	spin_lock_irq(&modlist_lock);
 	list_add(&mod->extable.list, &extables);
 	list_add_tail(&mod->symbols.list, &symbols);

@@ -1299,6 +1291,10 @@ sys_init_module(void *umod,
 	/* Start the module */
 	ret = mod->init();
 	if (ret < 0) {
+		/* If made active, it shouldn't be failing! */
+		if (mod->state == MODULE_STATE_LIVE)
+			__unsafe(mod);
+
 		/* Init routine failed: abort.  Try to protect us from
                    buggy refcounters. */
 		mod->state = MODULE_STATE_GOING;

@@ -1320,6 +1316,7 @@ sys_init_module(void *umod,
 	mod->module_init = NULL;
 	mod->init_size = 0;
 
+	module_live_notify(mod);
 	return 0;
 }