Commit 210b508e authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
Browse files

greybus: connection: serialise connection creation 



Serialise connection creation against concurrent creation and
destruction using a global mutex.

This is needed to prevent two drivers from attempting to create a
connection to the same interface CPort and to cope with a racing
connection destroy when moving to driver managed connections.

Note that the locking can not (easily) be made more fine-grained as not
all connections have an interface, but these are not hot paths anyway.

Reviewed-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarJohan Hovold <johan@hovoldconsulting.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent 0e46fab7

drivers/staging/greybus/connection.c

+16 −1
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ static void gb_connection_kref_release(struct kref *kref); 




static DEFINE_SPINLOCK(gb_connections_lock);

static DEFINE_MUTEX(gb_connection_mutex);





/* This is only used at initialization time; no locking is required. */

static struct gb_connection *
@@ -125,6 +127,9 @@ static void gb_connection_init_name(struct gb_connection *connection) 
 * A connection also maintains the state of operations sent over the

 * connection.

 *

 * Serialised against concurrent create and destroy using the

 * gb_connection_mutex.

 *

 * Return: A pointer to the new connection if successful, or NULL otherwise.

 */

static struct gb_connection *
@@ -159,9 +164,11 @@ gb_connection_create(struct gb_host_device *hd, int hd_cport_id, 
		return NULL;

	}



	mutex_lock(&gb_connection_mutex);



	hd_cport_id = ida_simple_get(id_map, ida_start, ida_end, GFP_KERNEL);

	if (hd_cport_id < 0)

		return NULL;

		goto err_unlock;



	connection = kzalloc(sizeof(*connection), GFP_KERNEL);

	if (!connection)
@@ -201,12 +208,16 @@ gb_connection_create(struct gb_host_device *hd, int hd_cport_id, 


	spin_unlock_irq(&gb_connections_lock);



	mutex_unlock(&gb_connection_mutex);



	return connection;



err_free_connection:

	kfree(connection);

err_remove_ida:

	ida_simple_remove(id_map, hd_cport_id);

err_unlock:

	mutex_unlock(&gb_connection_mutex);



	return NULL;

}
@@ -524,6 +535,8 @@ void gb_connection_destroy(struct gb_connection *connection) 
	if (!connection)

		return;



	mutex_lock(&gb_connection_mutex);



	spin_lock_irq(&gb_connections_lock);

	list_del(&connection->bundle_links);

	list_del(&connection->hd_links);
@@ -535,6 +548,8 @@ void gb_connection_destroy(struct gb_connection *connection) 
	ida_simple_remove(id_map, connection->hd_cport_id);

	connection->hd_cport_id = CPORT_ID_BAD;



	mutex_unlock(&gb_connection_mutex);



	gb_connection_put(connection);

}