Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

Pull module fixes and a virtio block fix from Rusty Russell:
 "Various minor fixes, but a slightly more complex one to fix the
  per-cpu overload problem introduced recently by kvm id changes."

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  module: put modules in list much earlier.
  module: add new state MODULE_STATE_UNFORMED.
  module: prevent warning when finit_module a 0 sized file
  virtio-blk: Don't free ida when disk is in use

5 files changed, 122 insertions, 52 deletions

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 9d8409c02082..8ad21a25bc0d 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -889,6 +889,7 @@ static void virtblk_remove(struct virtio_device *vdev)
 {
 	struct virtio_blk *vblk = vdev->priv;
 	int index = vblk->index;
+	int refc;
 
 	/* Prevent config work handler from accessing the device. */
 	mutex_lock(&vblk->config_lock);
@@ -903,11 +904,15 @@ static void virtblk_remove(struct virtio_device *vdev)
 
 	flush_work(&vblk->config_work);
 
+	refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
 	put_disk(vblk->disk);
 	mempool_destroy(vblk->pool);
 	vdev->config->del_vqs(vdev);
 	kfree(vblk);
-	ida_simple_remove(&vd_index_ida, index);
+
+	/* Only free device id if we don't have any users */
+	if (refc == 1)
+		ida_simple_remove(&vd_index_ida, index);
 }
 
 #ifdef CONFIG_PM
diff --git a/include/linux/module.h b/include/linux/module.h
index 7760c6d344a3..1375ee3f03aa 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -199,11 +199,11 @@ struct module_use {
 	struct module *source, *target;
 };
 
-enum module_state
-{
-	MODULE_STATE_LIVE,
-	MODULE_STATE_COMING,
-	MODULE_STATE_GOING,
+enum module_state {
+	MODULE_STATE_LIVE,	/* Normal state. */
+	MODULE_STATE_COMING,	/* Full formed, running module_init. */
+	MODULE_STATE_GOING,	/* Going away. */
+	MODULE_STATE_UNFORMED,	/* Still setting it up. */
 };
 
 /**
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 4d5f8d5612f3..8875254120b6 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1970,6 +1970,8 @@ static int kdb_lsmod(int argc, const char **argv)
 
 	kdb_printf("Module                  Size  modstruct     Used by\n");
 	list_for_each_entry(mod, kdb_modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 
 		kdb_printf("%-20s%8u  0x%p ", mod->name,
 			   mod->core_size, (void *)mod);
diff --git a/kernel/module.c b/kernel/module.c
index b10b048367e1..d25e359279ae 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -188,6 +188,7 @@ struct load_info {
    ongoing or failed initialization etc. */
 static inline int strong_try_module_get(struct module *mod)
 {
+	BUG_ON(mod && mod->state == MODULE_STATE_UNFORMED);
 	if (mod && mod->state == MODULE_STATE_COMING)
 		return -EBUSY;
 	if (try_module_get(mod))
@@ -343,6 +344,9 @@ bool each_symbol_section(bool (*fn)(const struct symsearch *arr,
 #endif
 		};
 
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
+
 		if (each_symbol_in_section(arr, ARRAY_SIZE(arr), mod, fn, data))
 			return true;
 	}
@@ -450,16 +454,24 @@ const struct kernel_symbol *find_symbol(const char *name,
 EXPORT_SYMBOL_GPL(find_symbol);
 
 /* Search for module by name: must hold module_mutex. */
-struct module *find_module(const char *name)
+static struct module *find_module_all(const char *name,
+				      bool even_unformed)
 {
 	struct module *mod;
 
 	list_for_each_entry(mod, &modules, list) {
+		if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		if (strcmp(mod->name, name) == 0)
 			return mod;
 	}
 	return NULL;
 }
+
+struct module *find_module(const char *name)
+{
+	return find_module_all(name, false);
+}
 EXPORT_SYMBOL_GPL(find_module);
 
 #ifdef CONFIG_SMP
@@ -525,6 +537,8 @@ bool is_module_percpu_address(unsigned long addr)
 	preempt_disable();
 
 	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		if (!mod->percpu_size)
 			continue;
 		for_each_possible_cpu(cpu) {
@@ -1048,6 +1062,8 @@ static ssize_t show_initstate(struct module_attribute *mattr,
 	case MODULE_STATE_GOING:
 		state = "going";
 		break;
+	default:
+		BUG();
 	}
 	return sprintf(buffer, "%s\n", state);
 }
@@ -1786,6 +1802,8 @@ void set_all_modules_text_rw(void)
 
 	mutex_lock(&module_mutex);
 	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		if ((mod->module_core) && (mod->core_text_size)) {
 			set_page_attributes(mod->module_core,
 						mod->module_core + mod->core_text_size,
@@ -1807,6 +1825,8 @@ void set_all_modules_text_ro(void)
 
 	mutex_lock(&module_mutex);
 	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		if ((mod->module_core) && (mod->core_text_size)) {
 			set_page_attributes(mod->module_core,
 						mod->module_core + mod->core_text_size,
@@ -2527,6 +2547,13 @@ static int copy_module_from_fd(int fd, struct load_info *info)
 		err = -EFBIG;
 		goto out;
 	}
+
+	/* Don't hand 0 to vmalloc, it whines. */
+	if (stat.size == 0) {
+		err = -EINVAL;
+		goto out;
+	}
+
 	info->hdr = vmalloc(stat.size);
 	if (!info->hdr) {
 		err = -ENOMEM;
@@ -2990,8 +3017,9 @@ static bool finished_loading(const char *name)
 	bool ret;
 
 	mutex_lock(&module_mutex);
-	mod = find_module(name);
-	ret = !mod || mod->state != MODULE_STATE_COMING;
+	mod = find_module_all(name, true);
+	ret = !mod || mod->state == MODULE_STATE_LIVE
+		|| mod->state == MODULE_STATE_GOING;
 	mutex_unlock(&module_mutex);
 
 	return ret;
@@ -3136,6 +3164,32 @@ static int load_module(struct load_info *info, const char __user *uargs,
 		goto free_copy;
 	}
 
+	/*
+	 * We try to place it in the list now to make sure it's unique
+	 * before we dedicate too many resources.  In particular,
+	 * temporary percpu memory exhaustion.
+	 */
+	mod->state = MODULE_STATE_UNFORMED;
+again:
+	mutex_lock(&module_mutex);
+	if ((old = find_module_all(mod->name, true)) != NULL) {
+		if (old->state == MODULE_STATE_COMING
+		    || old->state == MODULE_STATE_UNFORMED) {
+			/* Wait in case it fails to load. */
+			mutex_unlock(&module_mutex);
+			err = wait_event_interruptible(module_wq,
+					       finished_loading(mod->name));
+			if (err)
+				goto free_module;
+			goto again;
+		}
+		err = -EEXIST;
+		mutex_unlock(&module_mutex);
+		goto free_module;
+	}
+	list_add_rcu(&mod->list, &modules);
+	mutex_unlock(&module_mutex);
+
 #ifdef CONFIG_MODULE_SIG
 	mod->sig_ok = info->sig_ok;
 	if (!mod->sig_ok)
@@ -3145,7 +3199,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
 	/* Now module is in final location, initialize linked lists, etc. */
 	err = module_unload_init(mod);
 	if (err)
-		goto free_module;
+		goto unlink_mod;
 
 	/* Now we've got everything in the final locations, we can
 	 * find optional sections. */
@@ -3180,54 +3234,33 @@ static int load_module(struct load_info *info, const char __user *uargs,
 		goto free_arch_cleanup;
 	}
 
-	/* Mark state as coming so strong_try_module_get() ignores us. */
-	mod->state = MODULE_STATE_COMING;
-
-	/* Now sew it into the lists so we can get lockdep and oops
-	 * info during argument parsing.  No one should access us, since
-	 * strong_try_module_get() will fail.
-	 * lockdep/oops can run asynchronous, so use the RCU list insertion
-	 * function to insert in a way safe to concurrent readers.
-	 * The mutex protects against concurrent writers.
-	 */
-again:
-	mutex_lock(&module_mutex);
-	if ((old = find_module(mod->name)) != NULL) {
-		if (old->state == MODULE_STATE_COMING) {
-			/* Wait in case it fails to load. */
-			mutex_unlock(&module_mutex);
-			err = wait_event_interruptible(module_wq,
-					       finished_loading(mod->name));
-			if (err)
-				goto free_arch_cleanup;
-			goto again;
-		}
-		err = -EEXIST;
-		goto unlock;
-	}
-
-	/* This has to be done once we're sure module name is unique. */
 	dynamic_debug_setup(info->debug, info->num_debug);
 
-	/* Find duplicate symbols */
+	mutex_lock(&module_mutex);
+	/* Find duplicate symbols (must be called under lock). */
 	err = verify_export_symbols(mod);
 	if (err < 0)
-		goto ddebug;
+		goto ddebug_cleanup;
 
+	/* This relies on module_mutex for list integrity. */
 	module_bug_finalize(info->hdr, info->sechdrs, mod);
-	list_add_rcu(&mod->list, &modules);
+
+	/* Mark state as coming so strong_try_module_get() ignores us,
+	 * but kallsyms etc. can see us. */
+	mod->state = MODULE_STATE_COMING;
+
 	mutex_unlock(&module_mutex);
 
 	/* Module is ready to execute: parsing args may do that. */
 	err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
 			 -32768, 32767, &ddebug_dyndbg_module_param_cb);
 	if (err < 0)
-		goto unlink;
+		goto bug_cleanup;
 
 	/* Link in to syfs. */
 	err = mod_sysfs_setup(mod, info, mod->kp, mod->num_kp);
 	if (err < 0)
-		goto unlink;
+		goto bug_cleanup;
 
 	/* Get rid of temporary copy. */
 	free_copy(info);
@@ -3237,16 +3270,13 @@ again:
 
 	return do_init_module(mod);
 
- unlink:
+ bug_cleanup:
+	/* module_bug_cleanup needs module_mutex protection */
 	mutex_lock(&module_mutex);
-	/* Unlink carefully: kallsyms could be walking list. */
-	list_del_rcu(&mod->list);
 	module_bug_cleanup(mod);
-	wake_up_all(&module_wq);
- ddebug:
-	dynamic_debug_remove(info->debug);
- unlock:
 	mutex_unlock(&module_mutex);
+ ddebug_cleanup:
+	dynamic_debug_remove(info->debug);
 	synchronize_sched();
 	kfree(mod->args);
  free_arch_cleanup:
@@ -3255,6 +3285,12 @@ again:
 	free_modinfo(mod);
  free_unload:
 	module_unload_free(mod);
+ unlink_mod:
+	mutex_lock(&module_mutex);
+	/* Unlink carefully: kallsyms could be walking list. */
+	list_del_rcu(&mod->list);
+	wake_up_all(&module_wq);
+	mutex_unlock(&module_mutex);
  free_module:
 	module_deallocate(mod, info);
  free_copy:
@@ -3377,6 +3413,8 @@ const char *module_address_lookup(unsigned long addr,
 
 	preempt_disable();
 	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		if (within_module_init(addr, mod) ||
 		    within_module_core(addr, mod)) {
 			if (modname)
@@ -3400,6 +3438,8 @@ int lookup_module_symbol_name(unsigned long addr, char *symname)
 
 	preempt_disable();
 	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		if (within_module_init(addr, mod) ||
 		    within_module_core(addr, mod)) {
 			const char *sym;
@@ -3424,6 +3464,8 @@ int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size,
 
 	preempt_disable();
 	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		if (within_module_init(addr, mod) ||
 		    within_module_core(addr, mod)) {
 			const char *sym;
@@ -3451,6 +3493,8 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 
 	preempt_disable();
 	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		if (symnum < mod->num_symtab) {
 			*value = mod->symtab[symnum].st_value;
 			*type = mod->symtab[symnum].st_info;
@@ -3493,9 +3537,12 @@ unsigned long module_kallsyms_lookup_name(const char *name)
 			ret = mod_find_symname(mod, colon+1);
 		*colon = ':';
 	} else {
-		list_for_each_entry_rcu(mod, &modules, list)
+		list_for_each_entry_rcu(mod, &modules, list) {
+			if (mod->state == MODULE_STATE_UNFORMED)
+				continue;
 			if ((ret = mod_find_symname(mod, name)) != 0)
 				break;
+		}
 	}
 	preempt_enable();
 	return ret;
@@ -3510,6 +3557,8 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
 	int ret;
 
 	list_for_each_entry(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		for (i = 0; i < mod->num_symtab; i++) {
 			ret = fn(data, mod->strtab + mod->symtab[i].st_name,
 				 mod, mod->symtab[i].st_value);
@@ -3525,6 +3574,7 @@ static char *module_flags(struct module *mod, char *buf)
 {
 	int bx = 0;
 
+	BUG_ON(mod->state == MODULE_STATE_UNFORMED);
 	if (mod->taints ||
 	    mod->state == MODULE_STATE_GOING ||
 	    mod->state == MODULE_STATE_COMING) {
@@ -3566,6 +3616,10 @@ static int m_show(struct seq_file *m, void *p)
 	struct module *mod = list_entry(p, struct module, list);
 	char buf[8];
 
+	/* We always ignore unformed modules. */
+	if (mod->state == MODULE_STATE_UNFORMED)
+		return 0;
+
 	seq_printf(m, "%s %u",
 		   mod->name, mod->init_size + mod->core_size);
 	print_unload_info(m, mod);
@@ -3626,6 +3680,8 @@ const struct exception_table_entry *search_module_extables(unsigned long addr)
 
 	preempt_disable();
 	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		if (mod->num_exentries == 0)
 			continue;
 
@@ -3674,10 +3730,13 @@ struct module *__module_address(unsigned long addr)
 	if (addr < module_addr_min || addr > module_addr_max)
 		return NULL;
 
-	list_for_each_entry_rcu(mod, &modules, list)
+	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		if (within_module_core(addr, mod)
 		    || within_module_init(addr, mod))
 			return mod;
+	}
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(__module_address);
@@ -3730,8 +3789,11 @@ void print_modules(void)
 	printk(KERN_DEFAULT "Modules linked in:");
 	/* Most callers should already have preempt disabled, but make sure */
 	preempt_disable();
-	list_for_each_entry_rcu(mod, &modules, list)
+	list_for_each_entry_rcu(mod, &modules, list) {
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
 		printk(" %s%s", mod->name, module_flags(mod, buf));
+	}
 	preempt_enable();
 	if (last_unloaded_module[0])
 		printk(" [last unloaded: %s]", last_unloaded_module);
diff --git a/lib/bug.c b/lib/bug.c
index a28c1415357c..d0cdf14c651a 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -55,6 +55,7 @@ static inline unsigned long bug_addr(const struct bug_entry *bug)
 }
 
 #ifdef CONFIG_MODULES
+/* Updates are protected by module mutex */
 static LIST_HEAD(module_bug_list);
 
 static const struct bug_entry *module_find_bug(unsigned long bugaddr)