diff options
Diffstat (limited to 'drivers/media/usb/uvc/uvc_status.c')
| -rw-r--r-- | drivers/media/usb/uvc/uvc_status.c | 40 |
1 files changed, 39 insertions, 1 deletions
diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c index 883e4cab4..141ac1ffb 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -11,6 +11,7 @@ * */ +#include <asm/barrier.h> #include <linux/kernel.h> #include <linux/input.h> #include <linux/slab.h> @@ -184,7 +185,8 @@ static bool uvc_event_control(struct urb *urb, switch (status->bAttribute) { case UVC_CTRL_VALUE_CHANGE: - return uvc_ctrl_status_event(urb, chain, ctrl, status->bValue); + return uvc_ctrl_status_event_async(urb, chain, ctrl, + status->bValue); case UVC_CTRL_INFO_CHANGE: case UVC_CTRL_FAILURE_CHANGE: @@ -314,5 +316,41 @@ int uvc_status_start(struct uvc_device *dev, gfp_t flags) void uvc_status_stop(struct uvc_device *dev) { + struct uvc_ctrl_work *w = &dev->async_ctrl; + + /* + * Prevent the asynchronous control handler from requeing the URB. The + * barrier is needed so the flush_status change is visible to other + * CPUs running the asynchronous handler before usb_kill_urb() is + * called below. + */ + smp_store_release(&dev->flush_status, true); + + /* + * Cancel any pending asynchronous work. If any status event was queued, + * process it synchronously. + */ + if (cancel_work_sync(&w->work)) + uvc_ctrl_status_event(w->chain, w->ctrl, w->data); + + /* Kill the urb. */ usb_kill_urb(dev->int_urb); + + /* + * The URB completion handler may have queued asynchronous work. This + * won't resubmit the URB as flush_status is set, but it needs to be + * cancelled before returning or it could then race with a future + * uvc_status_start() call. + */ + if (cancel_work_sync(&w->work)) + uvc_ctrl_status_event(w->chain, w->ctrl, w->data); + + /* + * From this point, there are no events on the queue and the status URB + * is dead. No events will be queued until uvc_status_start() is called. + * The barrier is needed to make sure that flush_status is visible to + * uvc_ctrl_status_event_work() when uvc_status_start() will be called + * again. + */ + smp_store_release(&dev->flush_status, false); } |