disable FB

hc

2024-01-04 1543e317f1da31b75942316931e8f491a8920811

 kernel/drivers/media/usb/uvc/uvc_status.c
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@@ -6,6 +6,7 @@
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  *          Laurent Pinchart (laurent.pinchart@ideasonboard.com)
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  */
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+#include <asm/barrier.h>
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 #include <linux/kernel.h>
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 #include <linux/input.h>
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 #include <linux/slab.h>
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@@ -179,7 +180,8 @@
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 	switch (status->bAttribute) {
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 	case UVC_CTRL_VALUE_CHANGE:
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-		return uvc_ctrl_status_event(urb, chain, ctrl, status->bValue);
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+		return uvc_ctrl_status_event_async(urb, chain, ctrl,
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+						   status->bValue);
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 	case UVC_CTRL_INFO_CHANGE:
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 	case UVC_CTRL_FAILURE_CHANGE:
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@@ -309,5 +311,41 @@
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 void uvc_status_stop(struct uvc_device *dev)
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 {
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+	struct uvc_ctrl_work *w = &dev->async_ctrl;
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+
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+	/*
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+	 * Prevent the asynchronous control handler from requeing the URB. The
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+	 * barrier is needed so the flush_status change is visible to other
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+	 * CPUs running the asynchronous handler before usb_kill_urb() is
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+	 * called below.
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+	 */
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+	smp_store_release(&dev->flush_status, true);
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+
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+	/*
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+	 * Cancel any pending asynchronous work. If any status event was queued,
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+	 * process it synchronously.
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+	 */
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+	if (cancel_work_sync(&w->work))
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+		uvc_ctrl_status_event(w->chain, w->ctrl, w->data);
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+
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+	/* Kill the urb. */
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 	usb_kill_urb(dev->int_urb);
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+
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+	/*
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+	 * The URB completion handler may have queued asynchronous work. This
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+	 * won't resubmit the URB as flush_status is set, but it needs to be
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+	 * cancelled before returning or it could then race with a future
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+	 * uvc_status_start() call.
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+	 */
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+	if (cancel_work_sync(&w->work))
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+		uvc_ctrl_status_event(w->chain, w->ctrl, w->data);
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+
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+	/*
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+	 * From this point, there are no events on the queue and the status URB
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+	 * is dead. No events will be queued until uvc_status_start() is called.
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+	 * The barrier is needed to make sure that flush_status is visible to
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+	 * uvc_ctrl_status_event_work() when uvc_status_start() will be called
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+	 * again.
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+	 */
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+	smp_store_release(&dev->flush_status, false);
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 }