From: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Date: Wed, 24 Nov 2021 10:38:57 +0000 (+0100)
Subject: media: cec: safely unhook lists in cec_data
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=2ddd03309433d39852945c2f85d36e796c558793;p=linux.git

media: cec: safely unhook lists in cec_data

smatch warns about data->list not being removed from list:

drivers/media/cec/core/cec-adap.c:926 cec_transmit_msg_fh() warn: '&data->list' not removed from list

It is a false warning, but it doesn't hurt to make the code more robust
and safely unhook data->list and data->xfer_list together with a WARN_ON
if this is actually ever needed (this really shouldn't happen).

Note that fixing the data->list warning just replaced it with a new similar
warning for data->xfer_list, so both needed to be addressed.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---

diff --git a/drivers/media/cec/core/cec-adap.c b/drivers/media/cec/core/cec-adap.c
index 79fa36de8a04a..da73eb50cce2f 100644
--- a/drivers/media/cec/core/cec-adap.c
+++ b/drivers/media/cec/core/cec-adap.c
@@ -342,7 +342,7 @@ static void cec_data_completed(struct cec_data *data)
 	 * Without that we would be referring to a closed filehandle.
 	 */
 	if (data->fh)
-		list_del(&data->xfer_list);
+		list_del_init(&data->xfer_list);
 
 	if (data->blocking) {
 		/*
@@ -898,6 +898,8 @@ int cec_transmit_msg_fh(struct cec_adapter *adap, struct cec_msg *msg,
 
 	if (fh)
 		list_add_tail(&data->xfer_list, &fh->xfer_list);
+	else
+		INIT_LIST_HEAD(&data->xfer_list);
 
 	list_add_tail(&data->list, &adap->transmit_queue);
 	adap->transmit_queue_sz++;
@@ -923,6 +925,10 @@ int cec_transmit_msg_fh(struct cec_adapter *adap, struct cec_msg *msg,
 
 	/* The transmit completed (possibly with an error) */
 	*msg = data->msg;
+	if (WARN_ON(!list_empty(&data->list)))
+		list_del(&data->list);
+	if (WARN_ON(!list_empty(&data->xfer_list)))
+		list_del(&data->xfer_list);
 	kfree(data);
 	return 0;
 }
diff --git a/drivers/media/cec/core/cec-api.c b/drivers/media/cec/core/cec-api.c
index 769e6b4cddce3..0edb7142afdb8 100644
--- a/drivers/media/cec/core/cec-api.c
+++ b/drivers/media/cec/core/cec-api.c
@@ -669,7 +669,7 @@ static int cec_release(struct inode *inode, struct file *filp)
 
 		data->blocking = false;
 		data->fh = NULL;
-		list_del(&data->xfer_list);
+		list_del_init(&data->xfer_list);
 	}
 	mutex_unlock(&adap->lock);
 	while (!list_empty(&fh->msgs)) {