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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: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
hifive-unleashed-5.1
Johan Hovold 2016-01-19 12:51:26 +01:00 committed by Greg Kroah-Hartman
parent 0e46fab7dd
commit 210b508e45
1 changed files with 16 additions and 1 deletions
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17
drivers/staging/greybus/connection.c
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@ -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);
}