[PATCH v16 05/32] v4l: async: Correctly serialise async sub-device unregistration
From: Sakari Ailus <sakari.ailus@linux.intel.com>
Date: 2017-10-26 07:53:15
Also in:
linux-acpi, linux-media
Subsystem:
media input infrastructure (v4l/dvb), the rest, v4l2 async and fwnode frameworks · Maintainers:
Mauro Carvalho Chehab, Linus Torvalds, Sakari Ailus
The check whether an async sub-device is bound to a notifier was performed without list_lock held, making it possible for another process to unbind the async sub-device before the sub-device unregistration function proceeds to take the lock. Fix this by first acquiring the lock and then proceeding with the check. Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Reviewed-by: Sebastian Reichel <redacted> Acked-by: Hans Verkuil <redacted> --- drivers/media/v4l2-core/v4l2-async.c | 18 +++++++----------- 1 file changed, 7 insertions(+), 11 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
index 4924481451ca..cde2cf2ab4b0 100644
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c@@ -298,20 +298,16 @@ EXPORT_SYMBOL(v4l2_async_register_subdev); void v4l2_async_unregister_subdev(struct v4l2_subdev *sd) { - struct v4l2_async_notifier *notifier = sd->notifier; - - if (!sd->asd) { - if (!list_empty(&sd->async_list)) - v4l2_async_cleanup(sd); - return; - } - mutex_lock(&list_lock); - list_add(&sd->asd->list, ¬ifier->waiting); + if (sd->asd) { + struct v4l2_async_notifier *notifier = sd->notifier; - if (notifier->unbind) - notifier->unbind(notifier, sd, sd->asd); + list_add(&sd->asd->list, ¬ifier->waiting); + + if (notifier->unbind) + notifier->unbind(notifier, sd, sd->asd); + } v4l2_async_cleanup(sd);
--
2.11.0