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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: Christian König <christian.koenig@amd.com>
Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Grigori Goronzy 2015-07-03 01:54:10 +02:00 committed by Alex Deucher
parent bd833144a2
commit 828202a382
1 changed files with 8 additions and 3 deletions
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11
drivers/gpu/drm/radeon/radeon_gem.c
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@ -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;
}