drm/etnaviv: don't flush workqueue in etnaviv_gpu_wait_obj_inactive

There is no need to synchronize with oustanding retire jobs if the object
has gone idle. Retire jobs only ever change the object state from active to
idle, not the other way around.

The IOVA put race is uncritical, as the GEM_WAIT ioctl itself is holding
a reference to the GEM object, so the retire worker will not pull the
object into the CPU domain, which is the thing we are trying to guard
against with etnaviv_gpu_wait_obj_inactive. The ordering of the various
counts and waits may change a bit, but the userspace visible behavior at
the bounds of the syscall are unchanged.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
index 95187ebe16606405ff1e1bc8c3d212d1e6cbc4de..3738383474fbbc0ebfd849d219105193323bd4b0 100644 (file)
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
@@ -1295,17 +1295,12 @@ int etnaviv_gpu_wait_obj_inactive(struct etnaviv_gpu *gpu,
        ret = wait_event_interruptible_timeout(gpu->fence_event,
                                               !is_active(etnaviv_obj),
                                               remaining);
-       if (ret > 0) {
-               struct etnaviv_drm_private *priv = gpu->drm->dev_private;
-
-               /* Synchronise with the retire worker */
-               flush_workqueue(priv->wq);
+       if (ret > 0)
                return 0;
-       } else if (ret == -ERESTARTSYS) {
+       else if (ret == -ERESTARTSYS)
                return -ERESTARTSYS;
-       } else {
+       else
                return -ETIMEDOUT;
-       }
 }
 
 int etnaviv_gpu_pm_get_sync(struct etnaviv_gpu *gpu)