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Commit facfb062 authored by Ville Syrjälä's avatar Ville Syrjälä Committed by Daniel Vetter
Browse files

drm: Limit the number of .get_vblank_counter() retries 



Pontential infinite loops in the vblank code are a bad idea. Add some
limits.

Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent a6e610dc

drivers/gpu/drm/drm_irq.c

+4 −2
Original line number Original line Diff line number Diff line
@@ -127,6 +127,7 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, 
	u32 cur_vblank, diff;

	u32 cur_vblank, diff;

	bool rc;

	bool rc;

	struct timeval t_vblank;

	struct timeval t_vblank;

	int count = DRM_TIMESTAMP_MAXRETRIES;





	/*

	/*

	 * Interrupts were disabled prior to this call, so deal with counter

	 * Interrupts were disabled prior to this call, so deal with counter
@@ -143,7 +144,7 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, 
	do {

	do {

		cur_vblank = dev->driver->get_vblank_counter(dev, pipe);

		cur_vblank = dev->driver->get_vblank_counter(dev, pipe);

		rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, flags);

		rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, flags);

	} while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe));

	} while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe) && --count > 0);





	/* Deal with counter wrap */

	/* Deal with counter wrap */

	diff = cur_vblank - vblank->last;

	diff = cur_vblank - vblank->last;
@@ -914,6 +915,7 @@ u32 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe, 
			      struct timeval *vblanktime)

			      struct timeval *vblanktime)

{

{

	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];

	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];

	int count = DRM_TIMESTAMP_MAXRETRIES;

	u32 cur_vblank;

	u32 cur_vblank;





	if (WARN_ON(pipe >= dev->num_crtcs))

	if (WARN_ON(pipe >= dev->num_crtcs))
@@ -929,7 +931,7 @@ u32 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe, 
		smp_rmb();

		smp_rmb();

		*vblanktime = vblanktimestamp(dev, pipe, cur_vblank);

		*vblanktime = vblanktimestamp(dev, pipe, cur_vblank);

		smp_rmb();

		smp_rmb();

	} while (cur_vblank != vblank->count);

	} while (cur_vblank != vblank->count && --count > 0);





	return cur_vblank;

	return cur_vblank;

}

}