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Commit 828202a3 authored by Grigori Goronzy's avatar Grigori Goronzy Committed by Alex Deucher
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drm/radeon: use RCU query for GEM_BUSY syscall 



We don't need to call the (expensive) radeon_bo_wait, checking the
fences via RCU is much faster. The reservation done by radeon_bo_wait
does not save us from any race conditions.

Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarGrigori Goronzy <greg@chown.ath.cx>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent bd833144

drivers/gpu/drm/radeon/radeon_gem.c

+8 −3
Original line number Diff line number Diff line
@@ -428,7 +428,6 @@ int radeon_gem_mmap_ioctl(struct drm_device *dev, void *data, 
int radeon_gem_busy_ioctl(struct drm_device *dev, void *data,

			  struct drm_file *filp)

{

	struct radeon_device *rdev = dev->dev_private;

	struct drm_radeon_gem_busy *args = data;

	struct drm_gem_object *gobj;

	struct radeon_bo *robj;
@@ -440,10 +439,16 @@ int radeon_gem_busy_ioctl(struct drm_device *dev, void *data, 
		return -ENOENT;

	}

	robj = gem_to_radeon_bo(gobj);

	r = radeon_bo_wait(robj, &cur_placement, true);



	r = reservation_object_test_signaled_rcu(robj->tbo.resv, true);

	if (r == 0)

		r = -EBUSY;

	else

		r = 0;



	cur_placement = ACCESS_ONCE(robj->tbo.mem.mem_type);

	args->domain = radeon_mem_type_to_domain(cur_placement);

	drm_gem_object_unreference_unlocked(gobj);

	r = radeon_gem_handle_lockup(rdev, r);

	return r;

}