From 52ae2b0f44615f17bd211a89227fcf39e4fd9cc1 Mon Sep 17 00:00:00 2001 From: Sakari Ailus Date: Tue, 3 Oct 2017 02:26:32 -0400 Subject: media: v4l: async: Correctly serialise async sub-device unregistration MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Sebastian Reichel Acked-by: Hans Verkuil Acked-by: Niklas Söderlund Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Rui Miguel Silva --- 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); -- cgit v1.2.3