linux-kernel - [PATCH 2/2] media: v4l2-async: Safely unregister an non-registered async subdev

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Message-Id: <20210226224938.18166-2-laurent.pinchart@ideasonboard.com>
Date:   Sat, 27 Feb 2021 00:49:38 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Sakari Ailus <sakari.ailus@...ux.intel.com>,
        linux-renesas-soc@...r.kernel.org,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
Subject: [PATCH 2/2] media: v4l2-async: Safely unregister an non-registered async subdev

From: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>

Make the V4L2 async framework a bit more robust by allowing to
unregister a non-registered async subdev. Otherwise the
v4l2_async_cleanup() will attempt to delete the async subdev from the
subdev_list with the corresponding list_head not initialized.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
---
 drivers/media/v4l2-core/v4l2-async.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
index 37cc0263b273..2347b7ac54d4 100644
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c
@@ -750,6 +750,9 @@ EXPORT_SYMBOL(v4l2_async_register_subdev);
 
 void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
 {
+	if (list_is_null(&sd->async_list))
+		return;
+
 	mutex_lock(&list_lock);
 
 	__v4l2_async_notifier_unregister(sd->subdev_notifier);
-- 
Regards,

Laurent Pinchart