diff mbox series

[v3,2/3] media: uvcvideo: Refactor the status irq API

Message ID 20240325-guenter-mini-v3-2-c4bc61d84e03@chromium.org
State New
Headers show
Series uvcvideo: Attempt N to land UVC race conditions fixes | expand

Commit Message

Ricardo Ribalda March 25, 2024, 4:31 p.m. UTC
There are two different use-cases of uvc_status():
	- adding/removing a user when the camera is open/closed
	- stopping/starting when the camera is suspended/resumed

Make the API reflect these two use-cases and move all the refcounting
and locking logic to the uvc_status.c file.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 13 ++-------
 drivers/media/usb/uvc/uvc_status.c | 57 ++++++++++++++++++++++++++++++++++++--
 drivers/media/usb/uvc/uvc_v4l2.c   | 22 ++++-----------
 drivers/media/usb/uvc/uvcvideo.h   | 10 ++++---
 4 files changed, 68 insertions(+), 34 deletions(-)

Comments

Sergey Senozhatsky March 26, 2024, 8:42 a.m. UTC | #1
On (24/03/25 16:31), Ricardo Ribalda wrote:
>  drivers/media/usb/uvc/uvc_driver.c | 13 ++-------
>  drivers/media/usb/uvc/uvc_status.c | 57 ++++++++++++++++++++++++++++++++++++--
>  drivers/media/usb/uvc/uvc_v4l2.c   | 22 ++++-----------
>  drivers/media/usb/uvc/uvcvideo.h   | 10 ++++---
>  4 files changed, 68 insertions(+), 34 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index 17fc945c8deb6..b579644ac0745 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -2116,7 +2116,6 @@ static int uvc_probe(struct usb_interface *intf,
>  	INIT_LIST_HEAD(&dev->streams);
>  	kref_init(&dev->ref);
>  	atomic_set(&dev->nmappings, 0);
> -	mutex_init(&dev->lock);

Where is this getting initialized?
Ricardo Ribalda March 26, 2024, 8:49 a.m. UTC | #2
Hi Sergey

On Tue, 26 Mar 2024 at 09:42, Sergey Senozhatsky
<senozhatsky@chromium.org> wrote:
>
> On (24/03/25 16:31), Ricardo Ribalda wrote:
> >  drivers/media/usb/uvc/uvc_driver.c | 13 ++-------
> >  drivers/media/usb/uvc/uvc_status.c | 57 ++++++++++++++++++++++++++++++++++++--
> >  drivers/media/usb/uvc/uvc_v4l2.c   | 22 ++++-----------
> >  drivers/media/usb/uvc/uvcvideo.h   | 10 ++++---
> >  4 files changed, 68 insertions(+), 34 deletions(-)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > index 17fc945c8deb6..b579644ac0745 100644
> > --- a/drivers/media/usb/uvc/uvc_driver.c
> > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > @@ -2116,7 +2116,6 @@ static int uvc_probe(struct usb_interface *intf,
> >       INIT_LIST_HEAD(&dev->streams);
> >       kref_init(&dev->ref);
> >       atomic_set(&dev->nmappings, 0);
> > -     mutex_init(&dev->lock);
>
> Where is this getting initialized?

in uvc_status_init((). It is now called status_lock

But it should be init before  (ep == NULL)... otherwise it will not
work in devices without the int_ep.

Let me send a new version

Thanks!




--
Ricardo Ribalda
Sergey Senozhatsky March 26, 2024, 8:59 a.m. UTC | #3
On (24/03/25 16:31), Ricardo Ribalda wrote:
>  
>  void uvc_status_unregister(struct uvc_device *dev)
>  {
> -	usb_kill_urb(dev->int_urb);
> +	uvc_status_suspend(dev);
>  	uvc_input_unregister(dev);
>  }


Was the removal of usb_kill_urb() intended? If so, does it deserve
to be a patch on its own?
diff mbox series

Patch

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 17fc945c8deb6..b579644ac0745 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2116,7 +2116,6 @@  static int uvc_probe(struct usb_interface *intf,
 	INIT_LIST_HEAD(&dev->streams);
 	kref_init(&dev->ref);
 	atomic_set(&dev->nmappings, 0);
-	mutex_init(&dev->lock);
 
 	dev->udev = usb_get_dev(udev);
 	dev->intf = usb_get_intf(intf);
@@ -2282,10 +2281,7 @@  static int uvc_suspend(struct usb_interface *intf, pm_message_t message)
 	/* Controls are cached on the fly so they don't need to be saved. */
 	if (intf->cur_altsetting->desc.bInterfaceSubClass ==
 	    UVC_SC_VIDEOCONTROL) {
-		mutex_lock(&dev->lock);
-		if (dev->users)
-			uvc_status_stop(dev);
-		mutex_unlock(&dev->lock);
+		uvc_status_suspend(dev);
 		return 0;
 	}
 
@@ -2316,12 +2312,7 @@  static int __uvc_resume(struct usb_interface *intf, int reset)
 				return ret;
 		}
 
-		mutex_lock(&dev->lock);
-		if (dev->users)
-			ret = uvc_status_start(dev, GFP_NOIO);
-		mutex_unlock(&dev->lock);
-
-		return ret;
+		return uvc_status_resume(dev);
 	}
 
 	list_for_each_entry(stream, &dev->streams, list) {
diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c
index a78a88c710e24..ff66482346dde 100644
--- a/drivers/media/usb/uvc/uvc_status.c
+++ b/drivers/media/usb/uvc/uvc_status.c
@@ -262,6 +262,8 @@  int uvc_status_init(struct uvc_device *dev)
 
 	uvc_input_init(dev);
 
+	mutex_init(&dev->status_lock);
+
 	dev->status = kzalloc(sizeof(*dev->status), GFP_KERNEL);
 	if (!dev->status)
 		return -ENOMEM;
@@ -292,7 +294,7 @@  int uvc_status_init(struct uvc_device *dev)
 
 void uvc_status_unregister(struct uvc_device *dev)
 {
-	usb_kill_urb(dev->int_urb);
+	uvc_status_suspend(dev);
 	uvc_input_unregister(dev);
 }
 
@@ -302,18 +304,22 @@  void uvc_status_cleanup(struct uvc_device *dev)
 	kfree(dev->status);
 }
 
-int uvc_status_start(struct uvc_device *dev, gfp_t flags)
+static int _uvc_status_start(struct uvc_device *dev, gfp_t flags)
 {
+	lockdep_assert_held(&dev->status_lock);
+
 	if (dev->int_urb == NULL)
 		return 0;
 
 	return usb_submit_urb(dev->int_urb, flags);
 }
 
-void uvc_status_stop(struct uvc_device *dev)
+static void _uvc_status_stop(struct uvc_device *dev)
 {
 	struct uvc_ctrl_work *w = &dev->async_ctrl;
 
+	lockdep_assert_held(&dev->status_lock);
+
 	/*
 	 * Prevent the asynchronous control handler from requeing the URB. The
 	 * barrier is needed so the flush_status change is visible to other
@@ -350,3 +356,48 @@  void uvc_status_stop(struct uvc_device *dev)
 	 */
 	smp_store_release(&dev->flush_status, false);
 }
+
+int uvc_status_resume(struct uvc_device *dev)
+{
+	int ret = 0;
+
+	mutex_lock(&dev->status_lock);
+	if (dev->status_users)
+		ret = _uvc_status_start(dev, GFP_NOIO);
+	mutex_unlock(&dev->status_lock);
+
+	return ret;
+}
+
+void uvc_status_suspend(struct uvc_device *dev)
+{
+	mutex_lock(&dev->status_lock);
+	if (dev->status_users)
+		_uvc_status_stop(dev);
+	mutex_unlock(&dev->status_lock);
+}
+
+int uvc_status_get(struct uvc_device *dev)
+{
+	int ret = 0;
+
+	mutex_lock(&dev->status_lock);
+	if (!dev->status_users)
+		ret = _uvc_status_start(dev, GFP_KERNEL);
+	if (!ret)
+		dev->status_users++;
+	mutex_unlock(&dev->status_lock);
+
+	return ret;
+}
+
+void uvc_status_put(struct uvc_device *dev)
+{
+	mutex_lock(&dev->status_lock);
+	if (dev->status_users == 1)
+		_uvc_status_stop(dev);
+	WARN_ON(!dev->status_users);
+	if (dev->status_users)
+		dev->status_users--;
+	mutex_unlock(&dev->status_lock);
+}
diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index f4988f03640ae..97c5407f66032 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -628,20 +628,13 @@  static int uvc_v4l2_open(struct file *file)
 		return -ENOMEM;
 	}
 
-	mutex_lock(&stream->dev->lock);
-	if (stream->dev->users == 0) {
-		ret = uvc_status_start(stream->dev, GFP_KERNEL);
-		if (ret < 0) {
-			mutex_unlock(&stream->dev->lock);
-			usb_autopm_put_interface(stream->dev->intf);
-			kfree(handle);
-			return ret;
-		}
+	ret = uvc_status_get(stream->dev);
+	if (ret) {
+		usb_autopm_put_interface(stream->dev->intf);
+		kfree(handle);
+		return ret;
 	}
 
-	stream->dev->users++;
-	mutex_unlock(&stream->dev->lock);
-
 	v4l2_fh_init(&handle->vfh, &stream->vdev);
 	v4l2_fh_add(&handle->vfh);
 	handle->chain = stream->chain;
@@ -670,10 +663,7 @@  static int uvc_v4l2_release(struct file *file)
 	kfree(handle);
 	file->private_data = NULL;
 
-	mutex_lock(&stream->dev->lock);
-	if (--stream->dev->users == 0)
-		uvc_status_stop(stream->dev);
-	mutex_unlock(&stream->dev->lock);
+	uvc_status_put(stream->dev);
 
 	usb_autopm_put_interface(stream->dev->intf);
 	return 0;
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 6fb0a78b1b009..00b600eb058cc 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -555,8 +555,6 @@  struct uvc_device {
 
 	const struct uvc_device_info *info;
 
-	struct mutex lock;		/* Protects users */
-	unsigned int users;
 	atomic_t nmappings;
 
 	/* Video control interface */
@@ -578,6 +576,8 @@  struct uvc_device {
 	struct usb_host_endpoint *int_ep;
 	struct urb *int_urb;
 	struct uvc_status *status;
+	struct mutex status_lock; /* Protects status_users */
+	unsigned int status_users;
 	bool flush_status;
 
 	struct input_dev *input;
@@ -744,8 +744,10 @@  int uvc_register_video_device(struct uvc_device *dev,
 int uvc_status_init(struct uvc_device *dev);
 void uvc_status_unregister(struct uvc_device *dev);
 void uvc_status_cleanup(struct uvc_device *dev);
-int uvc_status_start(struct uvc_device *dev, gfp_t flags);
-void uvc_status_stop(struct uvc_device *dev);
+int uvc_status_resume(struct uvc_device *dev);
+void uvc_status_suspend(struct uvc_device *dev);
+int uvc_status_get(struct uvc_device *dev);
+void uvc_status_put(struct uvc_device *dev);
 
 /* Controls */
 extern const struct uvc_control_mapping uvc_ctrl_power_line_mapping_limited;