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From: Ricardo Ribalda <ribalda@chromium.org>
Date: Mon, 15 Apr 2024 19:34:28 +0000
Subject: [PATCH 11/35] media: s2255: Use refcount_t instead of atomic_t for
 num_channels
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To: Martin Tuma <martin.tuma@digiteqautomotive.com>, 
 Mauro Carvalho Chehab <mchehab@kernel.org>, 
 Laurent Pinchart <laurent.pinchart@ideasonboard.com>, 
 Hans Verkuil <hverkuil-cisco@xs4all.nl>, 
 Hugues Fruchet <hugues.fruchet@foss.st.com>, 
 Alain Volmat <alain.volmat@foss.st.com>, 
 Maxime Coquelin <mcoquelin.stm32@gmail.com>, 
 Alexandre Torgue <alexandre.torgue@foss.st.com>, 
 Paul Kocialkowski <paul.kocialkowski@bootlin.com>, 
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 
 Chen-Yu Tsai <wens@csie.org>, Jernej Skrabec <jernej.skrabec@gmail.com>, 
 Samuel Holland <samuel@sholland.org>, 
 Sakari Ailus <sakari.ailus@linux.intel.com>, 
 Thierry Reding <thierry.reding@gmail.com>, 
 Jonathan Hunter <jonathanh@nvidia.com>, 
 Sowjanya Komatineni <skomatineni@nvidia.com>, 
 Luca Ceresoli <luca.ceresoli@bootlin.com>, 
 Matthias Brugger <matthias.bgg@gmail.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, 
 Hans Verkuil <hverkuil@xs4all.nl>, Sergey Kozlov <serjk@netup.ru>, 
 Abylay Ospan <aospan@netup.ru>, 
 Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>, 
 Dmitry Osipenko <digetx@gmail.com>, 
 Stanimir Varbanov <stanimir.k.varbanov@gmail.com>, 
 Vikash Garodia <quic_vgarodia@quicinc.com>, 
 Bryan O'Donoghue <bryan.odonoghue@linaro.org>, 
 Bjorn Andersson <andersson@kernel.org>, 
 Konrad Dybcio <konrad.dybcio@linaro.org>, 
 Benjamin Mugnier <benjamin.mugnier@foss.st.com>, 
 Sylvain Petinot <sylvain.petinot@foss.st.com>, 
 Jacopo Mondi <jacopo+renesas@jmondi.org>, 
 Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>, 
 Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>, 
 =?utf-8?q?Niklas_S=C3=B6derlund?= <niklas.soderlund+renesas@ragnatech.se>, 
 Pavel Machek <pavel@ucw.cz>
Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, 
 linux-stm32@st-md-mailman.stormreply.com, 
 linux-arm-kernel@lists.infradead.org, linux-staging@lists.linux.dev, 
 linux-sunxi@lists.linux.dev, linux-tegra@vger.kernel.org, 
 linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org, 
 Ricardo Ribalda <ribalda@chromium.org>

Use an API that resembles more the actual use of num_channels.

Found by cocci:
drivers/media/usb/s2255/s2255drv.c:2362:5-24: WARNING: atomic_dec_and_test variation before object free at line 2363.
drivers/media/usb/s2255/s2255drv.c:1557:5-24: WARNING: atomic_dec_and_test variation before object free at line 1558.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/s2255/s2255drv.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/media/usb/s2255/s2255drv.c b/drivers/media/usb/s2255/s2255drv.c
index 8e1de1e8bd12..a6e450181fd0 100644
--- a/drivers/media/usb/s2255/s2255drv.c
+++ b/drivers/media/usb/s2255/s2255drv.c
@@ -247,7 +247,7 @@ struct s2255_vc {
 struct s2255_dev {
 	struct s2255_vc         vc[MAX_CHANNELS];
 	struct v4l2_device      v4l2_dev;
-	atomic_t                num_channels;
+	refcount_t		num_channels;
 	int			frames;
 	struct mutex		lock;	/* channels[].vdev.lock */
 	struct mutex		cmdlock; /* protects cmdbuf */
@@ -1550,11 +1550,11 @@ static void s2255_video_device_release(struct video_device *vdev)
 		container_of(vdev, struct s2255_vc, vdev);
 
 	dprintk(dev, 4, "%s, chnls: %d\n", __func__,
-		atomic_read(&dev->num_channels));
+		refcount_read(&dev->num_channels));
 
 	v4l2_ctrl_handler_free(&vc->hdl);
 
-	if (atomic_dec_and_test(&dev->num_channels))
+	if (refcount_dec_and_test(&dev->num_channels))
 		s2255_destroy(dev);
 	return;
 }
@@ -1659,7 +1659,7 @@ static int s2255_probe_v4l(struct s2255_dev *dev)
 				"failed to register video device!\n");
 			break;
 		}
-		atomic_inc(&dev->num_channels);
+		refcount_inc(&dev->num_channels);
 		v4l2_info(&dev->v4l2_dev, "V4L2 device registered as %s\n",
 			  video_device_node_name(&vc->vdev));
 
@@ -1667,11 +1667,11 @@ static int s2255_probe_v4l(struct s2255_dev *dev)
 	pr_info("Sensoray 2255 V4L driver Revision: %s\n",
 		S2255_VERSION);
 	/* if no channels registered, return error and probe will fail*/
-	if (atomic_read(&dev->num_channels) == 0) {
+	if (refcount_read(&dev->num_channels) == 0) {
 		v4l2_device_unregister(&dev->v4l2_dev);
 		return ret;
 	}
-	if (atomic_read(&dev->num_channels) != MAX_CHANNELS)
+	if (refcount_read(&dev->num_channels) != MAX_CHANNELS)
 		pr_warn("s2255: Not all channels available.\n");
 	return 0;
 }
@@ -2221,7 +2221,7 @@ static int s2255_probe(struct usb_interface *interface,
 		goto errorFWDATA1;
 	}
 
-	atomic_set(&dev->num_channels, 0);
+	refcount_set(&dev->num_channels, 0);
 	dev->pid = id->idProduct;
 	dev->fw_data = kzalloc(sizeof(struct s2255_fw), GFP_KERNEL);
 	if (!dev->fw_data)
@@ -2341,12 +2341,12 @@ static void s2255_disconnect(struct usb_interface *interface)
 {
 	struct s2255_dev *dev = to_s2255_dev(usb_get_intfdata(interface));
 	int i;
-	int channels = atomic_read(&dev->num_channels);
+	int channels = refcount_read(&dev->num_channels);
 	mutex_lock(&dev->lock);
 	v4l2_device_disconnect(&dev->v4l2_dev);
 	mutex_unlock(&dev->lock);
 	/*see comments in the uvc_driver.c usb disconnect function */
-	atomic_inc(&dev->num_channels);
+	refcount_inc(&dev->num_channels);
 	/* unregister each video device. */
 	for (i = 0; i < channels; i++)
 		video_unregister_device(&dev->vc[i].vdev);
@@ -2359,7 +2359,7 @@ static void s2255_disconnect(struct usb_interface *interface)
 		dev->vc[i].vidstatus_ready = 1;
 		wake_up(&dev->vc[i].wait_vidstatus);
 	}
-	if (atomic_dec_and_test(&dev->num_channels))
+	if (refcount_dec_and_test(&dev->num_channels))
 		s2255_destroy(dev);
 	dev_info(&interface->dev, "%s\n", __func__);
 }

-- 
2.44.0.683.g7961c838ac-goog