releases/6.6.44/media-ivsc-csi-add-separate-lock-for-v4l2-control-handler.patch

From c6be6471004e0e4d10d0514146d8c41550823d63 Mon Sep 17 00:00:00 2001
From: Wentong Wu <wentong.wu@intel.com>
Date: Fri, 7 Jun 2024 21:25:46 +0800
Subject: media: ivsc: csi: add separate lock for v4l2 control handler

From: Wentong Wu <wentong.wu@intel.com>

commit c6be6471004e0e4d10d0514146d8c41550823d63 upstream.

There're possibilities that privacy status change notification happens
in the middle of the ongoing mei command which already takes the command
lock, but v4l2_ctrl_s_ctrl() would also need the same lock prior to this
patch, so this may results in circular locking problem. This patch adds
one dedicated lock for v4l2 control handler to avoid described issue.

Fixes: 29006e196a56 ("media: pci: intel: ivsc: Add CSI submodule")
Cc: stable@vger.kernel.org # for 6.6 and later
Reported-by: Hao Yao <hao.yao@intel.com>
Signed-off-by: Wentong Wu <wentong.wu@intel.com>
Tested-by: Jason Chen <jason.z.chen@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/media/pci/intel/ivsc/mei_csi.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/media/pci/intel/ivsc/mei_csi.c
+++ b/drivers/media/pci/intel/ivsc/mei_csi.c
@@ -124,6 +124,8 @@ struct mei_csi {
 	struct v4l2_ctrl_handler ctrl_handler;
 	struct v4l2_ctrl *freq_ctrl;
 	struct v4l2_ctrl *privacy_ctrl;
+	/* lock for v4l2 controls */
+	struct mutex ctrl_lock;
 	unsigned int remote_pad;
 	/* start streaming or not */
 	int streaming;
@@ -609,11 +611,13 @@ static int mei_csi_init_controls(struct
 	u32 max;
 	int ret;
 
+	mutex_init(&csi->ctrl_lock);
+
 	ret = v4l2_ctrl_handler_init(&csi->ctrl_handler, 2);
 	if (ret)
 		return ret;
 
-	csi->ctrl_handler.lock = &csi->lock;
+	csi->ctrl_handler.lock = &csi->ctrl_lock;
 
 	max = ARRAY_SIZE(link_freq_menu_items) - 1;
 	csi->freq_ctrl = v4l2_ctrl_new_int_menu(&csi->ctrl_handler,
@@ -772,6 +776,7 @@ err_entity:
 
 err_ctrl_handler:
 	v4l2_ctrl_handler_free(&csi->ctrl_handler);
+	mutex_destroy(&csi->ctrl_lock);
 	v4l2_async_nf_unregister(&csi->notifier);
 	v4l2_async_nf_cleanup(&csi->notifier);
 
@@ -791,6 +796,7 @@ static void mei_csi_remove(struct mei_cl
 	v4l2_async_nf_unregister(&csi->notifier);
 	v4l2_async_nf_cleanup(&csi->notifier);
 	v4l2_ctrl_handler_free(&csi->ctrl_handler);
+	mutex_destroy(&csi->ctrl_lock);
 	v4l2_async_unregister_subdev(&csi->subdev);
 	v4l2_subdev_cleanup(&csi->subdev);
 	media_entity_cleanup(&csi->subdev.entity);