media: hdpvr: fix locking and a missing msleep (6bc5a4a1) · Commits · 戴 / test

This driver has three locking issues: - The wait_event_interruptible() condition calls hdpvr_get_next_buffer(dev) which uses a mutex, which is not allowed. Rewrite with list_empty_careful() that doesn't need locking. - In hdpvr_read() the call to hdpvr_stop_streaming() didn't lock io_mutex, but it should have since stop_streaming expects that. - In hdpvr_device_release() io_mutex was locked when calling flush_work(), but there it shouldn't take that mutex since the work done by flush_work() also wants to lock that mutex. There are also two other changes (suggested by Keith): - msecs_to_jiffies(4000); (a NOP) should have been msleep(4000). - Change v4l2_dbg to v4l2_info to always log if streaming had to be restarted. Reported-by:

Keith Pyle <kpyle@austin.rr.com> Suggested-by:

Keith Pyle <kpyle@austin.rr.com> Signed-off-by:

Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by:

Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/hdpvr/hdpvr-video.c

+11 −6

Original line number	Diff line number	Diff line
		@@ -435,7 +435,7 @@ static ssize_t hdpvr_read(struct file file, char __user buffer, size_t count,
		/* wait for the first buffer */
		if (!(file->f_flags & O_NONBLOCK)) {
		if (wait_event_interruptible(dev->wait_data,
		hdpvr_get_next_buffer(dev)))
		!list_empty_careful(&dev->rec_buff_list)))
		return -ERESTARTSYS;
		}

		@@ -461,10 +461,17 @@ static ssize_t hdpvr_read(struct file file, char __user buffer, size_t count,
		goto err;
		}
		if (!err) {
		v4l2_dbg(MSG_INFO, hdpvr_debug, &dev->v4l2_dev,
		v4l2_info(&dev->v4l2_dev,
		"timeout: restart streaming\n");
		mutex_lock(&dev->io_mutex);
		hdpvr_stop_streaming(dev);
		msecs_to_jiffies(4000);
		mutex_unlock(&dev->io_mutex);
		/*
		* The FW needs about 4 seconds after streaming
		* stopped before it is ready to restart
		* streaming.
		*/
		msleep(4000);
		err = hdpvr_start_streaming(dev);
		if (err) {
		ret = err;
		@@ -1124,9 +1131,7 @@ static void hdpvr_device_release(struct video_device *vdev)
		struct hdpvr_device *dev = video_get_drvdata(vdev);

		hdpvr_delete(dev);
		mutex_lock(&dev->io_mutex);
		flush_work(&dev->worker);
		mutex_unlock(&dev->io_mutex);

		v4l2_device_unregister(&dev->v4l2_dev);
		v4l2_ctrl_handler_free(&dev->hdl);

Admin message