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module: clean up load_module a little more. 

1fb9341ac3 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>
This commit is contained in:
Rusty Russell 2013-01-21 17:18:59 +10:30
parent f2e207f324
commit a3535c7e4f
1 changed files with 68 additions and 39 deletions
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107
kernel/module.c
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@ -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);