1 files changed, 39 insertions, 27 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 68637e661d75..2ec961945fa8 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2261,15 +2261,26 @@ static void free_module(struct module *mod)
 void *__symbol_get(const char *symbol)
 {
 	struct module *owner;
+	enum mod_license license;
 	const struct kernel_symbol *sym;
 
 	preempt_disable();
-	sym = find_symbol(symbol, &owner, NULL, NULL, true, true);
-	if (sym && strong_try_module_get(owner))
+	sym = find_symbol(symbol, &owner, NULL, &license, true, true);
+	if (!sym)
+		goto fail;
+	if (license != GPL_ONLY) {
+		pr_warn("failing symbol_get of non-GPLONLY symbol %s.\n",
+			symbol);
+		goto fail;
+	}
+	if (strong_try_module_get(owner))
 		sym = NULL;
 	preempt_enable();
 
 	return sym ? (void *)kernel_symbol_value(sym) : NULL;
+fail:
+	preempt_enable();
+	return NULL;
 }
 EXPORT_SYMBOL_GPL(__symbol_get);
 
@@ -3478,7 +3489,8 @@ static bool finished_loading(const char *name)
 	sched_annotate_sleep();
 	mutex_lock(&module_mutex);
 	mod = find_module_all(name, strlen(name), true);
-	ret = !mod || mod->state == MODULE_STATE_LIVE;
+	ret = !mod || mod->state == MODULE_STATE_LIVE
+		|| mod->state == MODULE_STATE_GOING;
 	mutex_unlock(&module_mutex);
 
 	return ret;
@@ -3526,12 +3538,6 @@ static noinline int do_init_module(struct module *mod)
 	}
 	freeinit->module_init = mod->init_layout.base;
 
-	/*
-	 * We want to find out whether @mod uses async during init.  Clear
-	 * PF_USED_ASYNC.  async_schedule*() will set it.
-	 */
-	current->flags &= ~PF_USED_ASYNC;
-
 	do_mod_ctors(mod);
 	/* Start the module */
 	if (mod->init != NULL)
@@ -3557,22 +3563,13 @@ static noinline int do_init_module(struct module *mod)
 
 	/*
 	 * We need to finish all async code before the module init sequence
-	 * is done.  This has potential to deadlock.  For example, a newly
-	 * detected block device can trigger request_module() of the
-	 * default iosched from async probing task.  Once userland helper
-	 * reaches here, async_synchronize_full() will wait on the async
-	 * task waiting on request_module() and deadlock.
+	 * is done. This has potential to deadlock if synchronous module
+	 * loading is requested from async (which is not allowed!).
 	 *
-	 * This deadlock is avoided by perfomring async_synchronize_full()
-	 * iff module init queued any async jobs.  This isn't a full
-	 * solution as it will deadlock the same if module loading from
-	 * async jobs nests more than once; however, due to the various
-	 * constraints, this hack seems to be the best option for now.
-	 * Please refer to the following thread for details.
-	 *
-	 * http://thread.gmane.org/gmane.linux.kernel/1420814
+	 * See commit 0fdff3ec6d87 ("async, kmod: warn on synchronous
+	 * request_module() from async workers") for more details.
 	 */
-	if (!mod->async_probe_requested && (current->flags & PF_USED_ASYNC))
+	if (!mod->async_probe_requested)
 		async_synchronize_full();
 
 	ftrace_free_mem(mod, mod->init_layout.base, mod->init_layout.base +
@@ -3647,20 +3644,35 @@ static int add_unformed_module(struct module *mod)
 
 	mod->state = MODULE_STATE_UNFORMED;
 
-again:
 	mutex_lock(&module_mutex);
 	old = find_module_all(mod->name, strlen(mod->name), true);
 	if (old != NULL) {
-		if (old->state != MODULE_STATE_LIVE) {
+		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 out_unlocked;
-			goto again;
+
+			/* The module might have gone in the meantime. */
+			mutex_lock(&module_mutex);
+			old = find_module_all(mod->name, strlen(mod->name),
+					      true);
 		}
-		err = -EEXIST;
+
+		/*
+		 * We are here only when the same module was being loaded. Do
+		 * not try to load it again right now. It prevents long delays
+		 * caused by serialized module load failures. It might happen
+		 * when more devices of the same type trigger load of
+		 * a particular module.
+		 */
+		if (old && old->state == MODULE_STATE_LIVE)
+			err = -EEXIST;
+		else
+			err = -EBUSY;
 		goto out;
 	}
 	mod_update_bounds(mod);