Commit a9bf5c8a authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

tty: hvc: use mutex instead of spinlock for hvc_structs lock 



This allows hvc operations to sleep under the lock.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 021c9179

drivers/tty/hvc/hvc_console.c

+11 −12
Original line number Original line Diff line number Diff line
@@ -73,7 +73,7 @@ static LIST_HEAD(hvc_structs); 
 * Protect the list of hvc_struct instances from inserts and removals during

 * Protect the list of hvc_struct instances from inserts and removals during

 * list traversal.

 * list traversal.

 */

 */

static DEFINE_SPINLOCK(hvc_structs_lock);

static DEFINE_MUTEX(hvc_structs_mutex);





/*

/*

 * This value is used to assign a tty->index value to a hvc_struct based

 * This value is used to assign a tty->index value to a hvc_struct based
@@ -83,7 +83,7 @@ static DEFINE_SPINLOCK(hvc_structs_lock); 
static int last_hvc = -1;

static int last_hvc = -1;





/*

/*

 * Do not call this function with either the hvc_structs_lock or the hvc_struct

 * Do not call this function with either the hvc_structs_mutex or the hvc_struct

 * lock held.  If successful, this function increments the kref reference

 * lock held.  If successful, this function increments the kref reference

 * count against the target hvc_struct so it should be released when finished.

 * count against the target hvc_struct so it should be released when finished.

 */

 */
@@ -92,25 +92,24 @@ static struct hvc_struct *hvc_get_by_index(int index) 
	struct hvc_struct *hp;

	struct hvc_struct *hp;

	unsigned long flags;

	unsigned long flags;





	spin_lock(&hvc_structs_lock);

	mutex_lock(&hvc_structs_mutex);





	list_for_each_entry(hp, &hvc_structs, next) {

	list_for_each_entry(hp, &hvc_structs, next) {

		spin_lock_irqsave(&hp->lock, flags);

		spin_lock_irqsave(&hp->lock, flags);

		if (hp->index == index) {

		if (hp->index == index) {

			tty_port_get(&hp->port);

			tty_port_get(&hp->port);

			spin_unlock_irqrestore(&hp->lock, flags);

			spin_unlock_irqrestore(&hp->lock, flags);

			spin_unlock(&hvc_structs_lock);

			mutex_unlock(&hvc_structs_mutex);

			return hp;

			return hp;

		}

		}

		spin_unlock_irqrestore(&hp->lock, flags);

		spin_unlock_irqrestore(&hp->lock, flags);

	}

	}

	hp = NULL;

	hp = NULL;

	mutex_unlock(&hvc_structs_mutex);





	spin_unlock(&hvc_structs_lock);

	return hp;

	return hp;

}

}







/*

/*

 * Initial console vtermnos for console API usage prior to full console

 * Initial console vtermnos for console API usage prior to full console

 * initialization.  Any vty adapter outside this range will not have usable

 * initialization.  Any vty adapter outside this range will not have usable
@@ -224,13 +223,13 @@ static void hvc_port_destruct(struct tty_port *port) 
	struct hvc_struct *hp = container_of(port, struct hvc_struct, port);

	struct hvc_struct *hp = container_of(port, struct hvc_struct, port);

	unsigned long flags;

	unsigned long flags;





	spin_lock(&hvc_structs_lock);

	mutex_lock(&hvc_structs_mutex);





	spin_lock_irqsave(&hp->lock, flags);

	spin_lock_irqsave(&hp->lock, flags);

	list_del(&(hp->next));

	list_del(&(hp->next));

	spin_unlock_irqrestore(&hp->lock, flags);

	spin_unlock_irqrestore(&hp->lock, flags);





	spin_unlock(&hvc_structs_lock);

	mutex_unlock(&hvc_structs_mutex);





	kfree(hp);

	kfree(hp);

}

}
@@ -733,11 +732,11 @@ static int khvcd(void *unused) 
		try_to_freeze();

		try_to_freeze();

		wmb();

		wmb();

		if (!cpus_are_in_xmon()) {

		if (!cpus_are_in_xmon()) {

			spin_lock(&hvc_structs_lock);

			mutex_lock(&hvc_structs_mutex);

			list_for_each_entry(hp, &hvc_structs, next) {

			list_for_each_entry(hp, &hvc_structs, next) {

				poll_mask |= hvc_poll(hp);

				poll_mask |= hvc_poll(hp);

			}

			}

			spin_unlock(&hvc_structs_lock);

			mutex_unlock(&hvc_structs_mutex);

		} else

		} else

			poll_mask |= HVC_POLL_READ;

			poll_mask |= HVC_POLL_READ;

		if (hvc_kicked)

		if (hvc_kicked)
@@ -871,7 +870,7 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data, 




	INIT_WORK(&hp->tty_resize, hvc_set_winsz);

	INIT_WORK(&hp->tty_resize, hvc_set_winsz);

	spin_lock_init(&hp->lock);

	spin_lock_init(&hp->lock);

	spin_lock(&hvc_structs_lock);

	mutex_lock(&hvc_structs_mutex);





	/*

	/*

	 * find index to use:

	 * find index to use:
@@ -891,7 +890,7 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data, 
	vtermnos[i] = vtermno;

	vtermnos[i] = vtermno;





	list_add_tail(&(hp->next), &hvc_structs);

	list_add_tail(&(hp->next), &hvc_structs);

	spin_unlock(&hvc_structs_lock);

	mutex_unlock(&hvc_structs_mutex);





	/* check if we need to re-register the kernel console */

	/* check if we need to re-register the kernel console */

	hvc_check_console(i);

	hvc_check_console(i);