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Commit 9cc019b8 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Rusty Russell
Browse files

module: Replace over-engineered nested sleep 



Since the introduction of the nested sleep warning; we've established
that the occasional sleep inside a wait_event() is fine.

wait_event() loops are invariant wrt. spurious wakeups, and the
occasional sleep has a similar effect on them. As long as its occasional
its harmless.

Therefore replace the 'correct' but verbose wait_woken() thing with
a simple annotation to shut up the warning.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent d64810f5

kernel/module.c

+8 −28
Original line number Diff line number Diff line
@@ -2984,6 +2984,12 @@ static bool finished_loading(const char *name) 
	struct module *mod;

	bool ret;



	/*

	 * The module_mutex should not be a heavily contended lock;

	 * if we get the occasional sleep here, we'll go an extra iteration

	 * in the wait_event_interruptible(), which is harmless.

	 */

	sched_annotate_sleep();

	mutex_lock(&module_mutex);

	mod = find_module_all(name, strlen(name), true);

	ret = !mod || mod->state == MODULE_STATE_LIVE
@@ -3125,32 +3131,6 @@ static int may_init_module(void) 
	return 0;

}



/*

 * Can't use wait_event_interruptible() because our condition

 * 'finished_loading()' contains a blocking primitive itself (mutex_lock).

 */

static int wait_finished_loading(struct module *mod)

{

	DEFINE_WAIT_FUNC(wait, woken_wake_function);

	int ret = 0;



	add_wait_queue(&module_wq, &wait);

	for (;;) {

		if (finished_loading(mod->name))

			break;



		if (signal_pending(current)) {

			ret = -ERESTARTSYS;

			break;

		}



		wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);

	}

	remove_wait_queue(&module_wq, &wait);



	return ret;

}



/*

 * 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
@@ -3171,8 +3151,8 @@ static int add_unformed_module(struct module *mod) 
		    || old->state == MODULE_STATE_UNFORMED) {

			/* Wait in case it fails to load. */

			mutex_unlock(&module_mutex);



			err = wait_finished_loading(mod);

			err = wait_event_interruptible(module_wq,

					       finished_loading(mod->name));

			if (err)

				goto out_unlocked;

			goto again;