2 files changed, 51 insertions, 32 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index 6914fcad4673..680db9e2ac36 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -359,7 +359,9 @@ struct module
 
 #ifdef CONFIG_MODULE_UNLOAD
         /* What modules depend on me? */
-        struct list_head modules_which_use_me;
+        struct list_head source_list;
+        /* What modules do I depend on? */
+        struct list_head target_list;
 
         /* Who is waiting for us to be unloaded */
         struct task_struct *waiter;
diff --git a/kernel/module.c b/kernel/module.c
index 0129769301e3..be18c3e34684 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -523,7 +523,8 @@ static void module_unload_init(struct module *mod)
 {
         int cpu;
 
-        INIT_LIST_HEAD(&mod->modules_which_use_me);
+        INIT_LIST_HEAD(&mod->source_list);
+        INIT_LIST_HEAD(&mod->target_list);
         for_each_possible_cpu(cpu) {
                 per_cpu_ptr(mod->refptr, cpu)->incs = 0;
                 per_cpu_ptr(mod->refptr, cpu)->decs = 0;
@@ -538,8 +539,9 @@ static void module_unload_init(struct module *mod)
 /* modules using other modules */
 struct module_use
 {
-        struct list_head list;
-        struct module *module_which_uses;
+        struct list_head source_list;
+        struct list_head target_list;
+        struct module *source, *target;
 };
 
 /* Does a already use b? */
@@ -547,8 +549,8 @@ static int already_uses(struct module *a, struct module *b)
 {
         struct module_use *use;
 
-        list_for_each_entry(use, &b->modules_which_use_me, list) {
-                if (use->module_which_uses == a) {
+        list_for_each_entry(use, &b->source_list, source_list) {
+                if (use->source == a) {
                         DEBUGP("%s uses %s!\n", a->name, b->name);
                         return 1;
                 }
@@ -557,6 +559,33 @@ static int already_uses(struct module *a, struct module *b)
         return 0;
 }
 
+/*
+ * Module a uses b
+ *  - we add 'a' as a "source", 'b' as a "target" of module use
+ *  - the module_use is added to the list of 'b' sources (so
+ *    'b' can walk the list to see who sourced them), and of 'a'
+ *    targets (so 'a' can see what modules it targets).
+ */
+static int add_module_usage(struct module *a, struct module *b)
+{
+        int no_warn;
+        struct module_use *use;
+
+        DEBUGP("Allocating new usage for %s.\n", a->name);
+        use = kmalloc(sizeof(*use), GFP_ATOMIC);
+        if (!use) {
+                printk(KERN_WARNING "%s: out of memory loading\n", a->name);
+                return -ENOMEM;
+        }
+
+        use->source = a;
+        use->target = b;
+        list_add(&use->source_list, &b->source_list);
+        list_add(&use->target_list, &a->target_list);
+        no_warn = sysfs_create_link(b->holders_dir, &a->mkobj.kobj, a->name);
+        return 0;
+}
+
 /* Module a uses b */
 int use_module(struct module *a, struct module *b)
 {
@@ -578,17 +607,11 @@ int use_module(struct module *a, struct module *b)
         if (err)
                 return 0;
 
-        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);
+        err = add_module_usage(a, b);
+        if (err) {
                 module_put(b);
                 return 0;
         }
-
-        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;
 }
 EXPORT_SYMBOL_GPL(use_module);
@@ -596,22 +619,16 @@ EXPORT_SYMBOL_GPL(use_module);
 /* Clear the unload stuff of the module. */
 static void module_unload_free(struct module *mod)
 {
-        struct module *i;
-
-        list_for_each_entry(i, &modules, list) {
-                struct module_use *use;
+        struct module_use *use, *tmp;
 
-                list_for_each_entry(use, &i->modules_which_use_me, list) {
-                        if (use->module_which_uses == mod) {
-                                DEBUGP("%s unusing %s\n", mod->name, i->name);
-                                module_put(i);
-                                list_del(&use->list);
-                                kfree(use);
-                                sysfs_remove_link(i->holders_dir, mod->name);
-                                /* There can be at most one match. */
-                                break;
-                        }
-                }
+        list_for_each_entry_safe(use, tmp, &mod->target_list, target_list) {
+                struct module *i = use->target;
+                DEBUGP("%s unusing %s\n", mod->name, i->name);
+                module_put(i);
+                list_del(&use->source_list);
+                list_del(&use->target_list);
+                kfree(use);
+                sysfs_remove_link(i->holders_dir, mod->name);
         }
 }
 
@@ -735,7 +752,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
                 goto out;
         }
 
-        if (!list_empty(&mod->modules_which_use_me)) {
+        if (!list_empty(&mod->source_list)) {
                 /* Other modules depend on us: get rid of them first. */
                 ret = -EWOULDBLOCK;
                 goto out;
@@ -799,9 +816,9 @@ static inline void print_unload_info(struct seq_file *m, struct module *mod)
 
         /* Always include a trailing , so userspace can differentiate
            between this and the old multi-field proc format. */
-        list_for_each_entry(use, &mod->modules_which_use_me, list) {
+        list_for_each_entry(use, &mod->source_list, source_list) {
                 printed_something = 1;
-                seq_printf(m, "%s,", use->module_which_uses->name);
+                seq_printf(m, "%s,", use->source->name);
         }
 
         if (mod->init != NULL && mod->exit == NULL) {