module: Make the 'usage' lists be two-way

[net-next-2.6.git] / kernel / module.c

diff --git a/kernel/module.c b/kernel/module.c
index 0129769301e3106eb505576fbb495a64f289160c..be18c3e34684860e7fd394ed4c015fe67ddac7e8 100644 (file)
--- 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) {