Commit 9692df05 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'irq-urgent-2022-05-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull irq fix from Thomas Gleixner:
 "A fix for the threaded interrupt core.

  A quick sequence of request/free_irq() can result in a hang because
  the interrupt thread did not reach the thread function and got stopped
  in the kthread core already. That leaves a state active counter
  arround which makes a invocation of synchronized_irq() on that
  interrupt hang forever.

  Ensure that the thread reached the thread function in request_irq() to
  prevent that"

* tag 'irq-urgent-2022-05-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Synchronize interrupt thread startup
parents ede4c6d7 8707898e

kernel/irq/internals.h

+2 −0
Original line number Diff line number Diff line
@@ -29,12 +29,14 @@ extern struct irqaction chained_action; 
 * IRQTF_WARNED    - warning "IRQ_WAKE_THREAD w/o thread_fn" has been printed

 * IRQTF_AFFINITY  - irq thread is requested to adjust affinity

 * IRQTF_FORCED_THREAD  - irq action is force threaded

 * IRQTF_READY     - signals that irq thread is ready

 */

enum {

	IRQTF_RUNTHREAD,

	IRQTF_WARNED,

	IRQTF_AFFINITY,

	IRQTF_FORCED_THREAD,

	IRQTF_READY,

};



/*

kernel/irq/irqdesc.c

+2 −0
Original line number Diff line number Diff line
@@ -407,6 +407,7 @@ static struct irq_desc *alloc_desc(int irq, int node, unsigned int flags, 
	lockdep_set_class(&desc->lock, &irq_desc_lock_class);

	mutex_init(&desc->request_mutex);

	init_rcu_head(&desc->rcu);

	init_waitqueue_head(&desc->wait_for_threads);



	desc_set_defaults(irq, desc, node, affinity, owner);

	irqd_set(&desc->irq_data, flags);
@@ -575,6 +576,7 @@ int __init early_irq_init(void) 
		raw_spin_lock_init(&desc[i].lock);

		lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);

		mutex_init(&desc[i].request_mutex);

		init_waitqueue_head(&desc[i].wait_for_threads);

		desc_set_defaults(i, &desc[i], node, NULL, NULL);

	}

	return arch_early_irq_init();

kernel/irq/manage.c

+29 −10
Original line number Diff line number Diff line
@@ -1248,6 +1248,31 @@ static void irq_wake_secondary(struct irq_desc *desc, struct irqaction *action) 
	raw_spin_unlock_irq(&desc->lock);

}



/*

 * Internal function to notify that a interrupt thread is ready.

 */

static void irq_thread_set_ready(struct irq_desc *desc,

				 struct irqaction *action)

{

	set_bit(IRQTF_READY, &action->thread_flags);

	wake_up(&desc->wait_for_threads);

}



/*

 * Internal function to wake up a interrupt thread and wait until it is

 * ready.

 */

static void wake_up_and_wait_for_irq_thread_ready(struct irq_desc *desc,

						  struct irqaction *action)

{

	if (!action || !action->thread)

		return;



	wake_up_process(action->thread);

	wait_event(desc->wait_for_threads,

		   test_bit(IRQTF_READY, &action->thread_flags));

}



/*

 * Interrupt handler thread

 */
@@ -1259,6 +1284,8 @@ static int irq_thread(void *data) 
	irqreturn_t (*handler_fn)(struct irq_desc *desc,

			struct irqaction *action);



	irq_thread_set_ready(desc, action);



	sched_set_fifo(current);



	if (force_irqthreads() && test_bit(IRQTF_FORCED_THREAD,
@@ -1683,8 +1710,6 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) 
	}



	if (!shared) {

		init_waitqueue_head(&desc->wait_for_threads);



		/* Setup the type (level, edge polarity) if configured: */

		if (new->flags & IRQF_TRIGGER_MASK) {

			ret = __irq_set_trigger(desc,
@@ -1780,14 +1805,8 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) 


	irq_setup_timings(desc, new);



	/*

	 * Strictly no need to wake it up, but hung_task complains

	 * when no hard interrupt wakes the thread up.

	 */

	if (new->thread)

		wake_up_process(new->thread);

	if (new->secondary)

		wake_up_process(new->secondary->thread);

	wake_up_and_wait_for_irq_thread_ready(desc, new);

	wake_up_and_wait_for_irq_thread_ready(desc, new->secondary);



	register_irq_proc(irq, desc);

	new->dir = NULL;