From 08af5a2444f690bdf0b85e0d95a9370e3ed75d85 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Wed, 19 May 2010 17:33:39 -0600
Subject: [PATCH] --- yaml --- r: 197575 b: refs/heads/master c:
 480b02df3aa9f07d1c7df0cd8be7a5ca73893455 h: refs/heads/master i:   197573:
 4a6cd7181e1de4316124d98630b477ead7a72584   197571:
 863e1e9301e453b66e2be16832dd0825c1b4be05   197567:
 a0807bad4a7313f7014cd58205d665c521273cb3 v: v3

---
 [refs]                |  2 +-
 trunk/kernel/module.c | 59 +++++++++++++++++++++++++++----------------
 2 files changed, 38 insertions(+), 23 deletions(-)

diff --git a/[refs] b/[refs]
index 675a71cc3f2e..c2f0457bd78d 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: fedb3d27d9e8606b3867b5ae49d6258458a07a72
+refs/heads/master: 480b02df3aa9f07d1c7df0cd8be7a5ca73893455
diff --git a/trunk/kernel/module.c b/trunk/kernel/module.c
index e2564580f3f1..970d773aec62 100644
--- a/trunk/kernel/module.c
+++ b/trunk/kernel/module.c
@@ -561,33 +561,26 @@ int use_module(struct module *a, struct module *b)
 	struct module_use *use;
 	int no_warn, err;
 
-	if (b == NULL || already_uses(a, b)) return 1;
-
-	/* If we're interrupted or time out, we fail. */
-	if (wait_event_interruptible_timeout(
-		    module_wq, (err = strong_try_module_get(b)) != -EBUSY,
-		    30 * HZ) <= 0) {
-		printk("%s: gave up waiting for init of module %s.\n",
-		       a->name, b->name);
+	if (b == NULL || already_uses(a, b))
 		return 0;
-	}
 
-	/* If strong_try_module_get() returned a different error, we fail. */
+	/* If we're interrupted or time out, we fail. */
+	err = strong_try_module_get(b);
 	if (err)
-		return 0;
+		return err;
 
 	DEBUGP("Allocating new usage for %s.\n", a->name);
 	use = kmalloc(sizeof(*use), GFP_ATOMIC);
 	if (!use) {
 		printk("%s: out of memory loading\n", a->name);
 		module_put(b);
-		return 0;
+		return -ENOMEM;
 	}
 
 	use->module_which_uses = a;
 	list_add(&use->list, &b->modules_which_use_me);
 	no_warn = sysfs_create_link(b->holders_dir, &a->mkobj.kobj, a->name);
-	return 1;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(use_module);
 
@@ -880,7 +873,7 @@ static inline void module_unload_free(struct module *mod)
 
 int use_module(struct module *a, struct module *b)
 {
-	return strong_try_module_get(b) == 0;
+	return strong_try_module_get(b);
 }
 EXPORT_SYMBOL_GPL(use_module);
 
@@ -1051,17 +1044,39 @@ static const struct kernel_symbol *resolve_symbol(Elf_Shdr *sechdrs,
 	struct module *owner;
 	const struct kernel_symbol *sym;
 	const unsigned long *crc;
+	DEFINE_WAIT(wait);
+	int err;
+	long timeleft = 30 * HZ;
 
+again:
 	sym = find_symbol(name, &owner, &crc,
 			  !(mod->taints & (1 << TAINT_PROPRIETARY_MODULE)), true);
-	/* use_module can fail due to OOM,
-	   or module initialization or unloading */
-	if (sym) {
-		if (!check_version(sechdrs, versindex, name, mod, crc, owner)
-		    || !use_module(mod, owner))
-			sym = NULL;
-	}
-	return sym;
+	if (!sym)
+		return NULL;
+
+	if (!check_version(sechdrs, versindex, name, mod, crc, owner))
+		return NULL;
+
+	prepare_to_wait(&module_wq, &wait, TASK_INTERRUPTIBLE);
+	err = use_module(mod, owner);
+	if (likely(!err) || err != -EBUSY || signal_pending(current)) {
+		finish_wait(&module_wq, &wait);
+		return err ? NULL : sym;
+	}
+
+	/* Module is still loading.  Drop lock and wait. */
+	mutex_unlock(&module_mutex);
+	timeleft = schedule_timeout(timeleft);
+	mutex_lock(&module_mutex);
+	finish_wait(&module_wq, &wait);
+
+	/* Module might be gone entirely, or replaced.  Re-lookup. */
+	if (timeleft)
+		goto again;
+
+	printk(KERN_WARNING "%s: gave up waiting for init of module %s.\n",
+	       mod->name, owner->name);
+	return NULL;
 }
 
 /*