[PATCH] drm/ttm: fix ttm_bo_wait

[Christian König]

From: Christian König <christian.koenig at amd.com>

reservation_object_wait_timeout_rcu() should enable signaling even with a zero
timeout, but ttm_bo_wait() can also be called from atomic context and then it
is not a good idea to do this.

Fixes "reservation: revert "wait only with non-zero timeout specified (v3)"".

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 608c585..478d563 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1605,7 +1605,14 @@ EXPORT_SYMBOL(ttm_bo_unmap_virtual);
 int ttm_bo_wait(struct ttm_buffer_object *bo,
 		bool interruptible, bool no_wait)
 {
-	long timeout = no_wait ? 0 : 15 * HZ;
+	long timeout = 15 * HZ;
+
+	if (no_wait) {
+		if (reservation_object_test_signaled_rcu(bo->resv, true))
+			return 0;
+		else
+			return -EBUSY;
+	}
 
 	timeout = reservation_object_wait_timeout_rcu(bo->resv, true,
 						      interruptible, timeout);
-- 
2.5.0