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Subject: media: hdpvr: fix locking and a missing msleep Author: Hans Verkuil <[email protected]> Date: Thu Jun 20 07:43:41 2019 -0400 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 <[email protected]> Suggested-by: Keith Pyle <[email protected]> Signed-off-by: Hans Verkuil <[email protected]> Signed-off-by: Mauro Carvalho Chehab <[email protected]> drivers/media/usb/hdpvr/hdpvr-video.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) --- diff --git a/drivers/media/usb/hdpvr/hdpvr-video.c b/drivers/media/usb/hdpvr/hdpvr-video.c index 3786ddcc0d18..5b3e67b80627 100644 --- a/drivers/media/usb/hdpvr/hdpvr-video.c +++ b/drivers/media/usb/hdpvr/hdpvr-video.c @@ -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, - "timeout: restart streaming\n"); + 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); _______________________________________________ linuxtv-commits mailing list [email protected] https://www.linuxtv.org/cgi-bin/mailman/listinfo/linuxtv-commits
