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authorRusty Russell <rusty@rustcorp.com.au>2013-01-21 17:18:59 +1030
committerRusty Russell <rusty@rustcorp.com.au>2013-01-21 17:20:09 +1030
commita3535c7e4f4495fe947f7901d25447d80e04fe52 (patch)
tree1a1f78c2b6cc07561b624e7443dc6493b5b8e5e3 /kernel/module.c
parentf2e207f32422c7b9624d3393db015dfd118d9d22 (diff)
downloadlinux-linaro-stable-a3535c7e4f4495fe947f7901d25447d80e04fe52.tar.gz
module: clean up load_module a little more.
1fb9341ac34825aa40354e74d9a2c69df7d2c304 made our locking in load_module more complicated: we grab the mutex once to insert the module in the list, then again to upgrade it once it's formed. Since the locking is self-contained, it's neater to do this in separate functions. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'kernel/module.c')
-rw-r--r--kernel/module.c107
1 files changed, 68 insertions, 39 deletions
diff --git a/kernel/module.c b/kernel/module.c
index cc000dd6e4a8..921bed4794e9 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3145,12 +3145,72 @@ static int may_init_module(void)
return 0;
}
+/*
+ * 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
+ * memory exhaustion.
+ */
+static int add_unformed_module(struct module *mod)
+{
+ int err;
+ struct module *old;
+
+ mod->state = MODULE_STATE_UNFORMED;
+
+again:
+ mutex_lock(&module_mutex);
+ if ((old = find_module_all(mod->name, true)) != 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;
+ goto again;
+ }
+ err = -EEXIST;
+ goto out;
+ }
+ list_add_rcu(&mod->list, &modules);
+ err = 0;
+
+out:
+ mutex_unlock(&module_mutex);
+out_unlocked:
+ return err;
+}
+
+static int complete_formation(struct module *mod, struct load_info *info)
+{
+ int err;
+
+ mutex_lock(&module_mutex);
+
+ /* Find duplicate symbols (must be called under lock). */
+ err = verify_export_symbols(mod);
+ if (err < 0)
+ goto out;
+
+ /* This relies on module_mutex for list integrity. */
+ module_bug_finalize(info->hdr, info->sechdrs, mod);
+
+ /* Mark state as coming so strong_try_module_get() ignores us,
+ * but kallsyms etc. can see us. */
+ mod->state = MODULE_STATE_COMING;
+
+out:
+ mutex_unlock(&module_mutex);
+ return err;
+}
+
/* Allocate and load the module: note that size of section 0 is always
zero, and we rely on this for optional sections. */
static int load_module(struct load_info *info, const char __user *uargs,
int flags)
{
- struct module *mod, *old;
+ struct module *mod;
long err;
err = module_sig_check(info);
@@ -3168,31 +3228,10 @@ static int load_module(struct load_info *info, const char __user *uargs,
goto free_copy;
}
- /*
- * 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 memory exhaustion.
- */
- mod->state = MODULE_STATE_UNFORMED;
-again:
- mutex_lock(&module_mutex);
- if ((old = find_module_all(mod->name, true)) != 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 free_module;
- goto again;
- }
- err = -EEXIST;
- mutex_unlock(&module_mutex);
+ /* Reserve our place in the list. */
+ err = add_unformed_module(mod);
+ if (err)
goto free_module;
- }
- list_add_rcu(&mod->list, &modules);
- mutex_unlock(&module_mutex);
#ifdef CONFIG_MODULE_SIG
mod->sig_ok = info->sig_ok;
@@ -3245,21 +3284,11 @@ again:
dynamic_debug_setup(info->debug, info->num_debug);
- mutex_lock(&module_mutex);
- /* Find duplicate symbols (must be called under lock). */
- err = verify_export_symbols(mod);
- if (err < 0)
+ /* Finally it's fully formed, ready to start executing. */
+ err = complete_formation(mod, info);
+ if (err)
goto ddebug_cleanup;
- /* This relies on module_mutex for list integrity. */
- module_bug_finalize(info->hdr, info->sechdrs, mod);
-
- /* Mark state as coming so strong_try_module_get() ignores us,
- * but kallsyms etc. can see us. */
- mod->state = MODULE_STATE_COMING;
-
- mutex_unlock(&module_mutex);
-
/* Module is ready to execute: parsing args may do that. */
err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
-32768, 32767, &ddebug_dyndbg_module_param_cb);
@@ -3283,8 +3312,8 @@ again:
/* module_bug_cleanup needs module_mutex protection */
mutex_lock(&module_mutex);
module_bug_cleanup(mod);
- ddebug_cleanup:
mutex_unlock(&module_mutex);
+ ddebug_cleanup:
dynamic_debug_remove(info->debug);
synchronize_sched();
kfree(mod->args);