[PATCH v3 2/4] module: extract patient module check into helper

[Luis Chamberlain]

The patient module check inside add_unformed_module() is large
enough as we need it. It is a bit hard to read too, so just
move it to a helper and do the inverse checks first to help
shift the code and make it easier to read. The new helper then
is module_patient_check_exists().

To make this work we need to mvoe the finished_loading() up,
we do that without making any functional changes to that routine.

Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
---
 kernel/module/main.c | 112 +++++++++++++++++++++++--------------------
 1 file changed, 60 insertions(+), 52 deletions(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index 32554d8a5791..75b23257128d 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2447,27 +2447,6 @@ static int post_relocation(struct module *mod, const struct load_info *info)
 	return module_finalize(info->hdr, info->sechdrs, mod);
 }
 
-/* Is this module of this name done loading?  No locks held. */
-static bool finished_loading(const char *name)
-{
-	struct module *mod;
-	bool ret;
-
-	/*
-	 * The module_mutex should not be a heavily contended lock;
-	 * if we get the occasional sleep here, we'll go an extra iteration
-	 * in the wait_event_interruptible(), which is harmless.
-	 */
-	sched_annotate_sleep();
-	mutex_lock(&module_mutex);
-	mod = find_module_all(name, strlen(name), true);
-	ret = !mod || mod->state == MODULE_STATE_LIVE
-		|| mod->state == MODULE_STATE_GOING;
-	mutex_unlock(&module_mutex);
-
-	return ret;
-}
-
 /* Call module constructors. */
 static void do_mod_ctors(struct module *mod)
 {
@@ -2631,6 +2610,63 @@ static int may_init_module(void)
 	return 0;
 }
 
+/* Is this module of this name done loading?  No locks held. */
+static bool finished_loading(const char *name)
+{
+	struct module *mod;
+	bool ret;
+
+	/*
+	 * The module_mutex should not be a heavily contended lock;
+	 * if we get the occasional sleep here, we'll go an extra iteration
+	 * in the wait_event_interruptible(), which is harmless.
+	 */
+	sched_annotate_sleep();
+	mutex_lock(&module_mutex);
+	mod = find_module_all(name, strlen(name), true);
+	ret = !mod || mod->state == MODULE_STATE_LIVE
+		|| mod->state == MODULE_STATE_GOING;
+	mutex_unlock(&module_mutex);
+
+	return ret;
+}
+
+/* Must be called with module_mutex held */
+static int module_patient_check_exists(const char *name)
+{
+	struct module *old;
+	int err = 0;
+
+	old = find_module_all(name, strlen(name), true);
+	if (old == NULL)
+		return 0;
+
+	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(name));
+		mutex_lock(&module_mutex);
+		if (err)
+			return err;
+
+		/* The module might have gone in the meantime. */
+		old = find_module_all(name, strlen(name), true);
+	}
+
+	/*
+	 * 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)
+		return -EEXIST;
+	return -EBUSY;
+}
+
 /*
  * 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
@@ -2639,41 +2675,14 @@ static int may_init_module(void)
 static int add_unformed_module(struct module *mod)
 {
 	int err;
-	struct module *old;
 
 	mod->state = MODULE_STATE_UNFORMED;
 
 	mutex_lock(&module_mutex);
-	old = find_module_all(mod->name, strlen(mod->name), true);
-	if (old != 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 out_unlocked;
-
-			/* The module might have gone in the meantime. */
-			mutex_lock(&module_mutex);
-			old = find_module_all(mod->name, strlen(mod->name),
-					      true);
-		}
-
-		/*
-		 * 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;
+	err = module_patient_check_exists(mod->name);
+	if (err)
 		goto out;
-	}
+
 	mod_update_bounds(mod);
 	list_add_rcu(&mod->list, &modules);
 	mod_tree_insert(mod);
@@ -2681,7 +2690,6 @@ static int add_unformed_module(struct module *mod)
 
 out:
 	mutex_unlock(&module_mutex);
-out_unlocked:
 	return err;
 }
 
-- 
2.39.2