[PATCH] amdgpu_device_recover_vram always failed if only one node in shadow_list

[wentalou]

amdgpu_bo_restore_shadow would assign zero to r if succeeded.
r would remain zero if there is only one node in shadow_list.
current code would always return failure when r <= 0.
restart the timeout for each wait was a rather problematic bug as well.
The value of tmo SHOULD be changed, otherwise we wait tmo jiffies on each loop.
meanwhile, fix Call Trace by NULL of shadow->parent.

Change-Id: I7e836ec7ab6cd0f069aac24f88e454e906637541
Signed-off-by: Wentao Lou <Wentao.Lou at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index c4c61e9..5a2dc44 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -3183,7 +3183,7 @@ static int amdgpu_device_recover_vram(struct amdgpu_device *adev)
 
 		/* No need to recover an evicted BO */
 		if (shadow->tbo.mem.mem_type != TTM_PL_TT ||
-		    shadow->parent->tbo.mem.mem_type != TTM_PL_VRAM)
+		    shadow->parent == NULL || shadow->parent->tbo.mem.mem_type != TTM_PL_VRAM)
 			continue;
 
 		r = amdgpu_bo_restore_shadow(shadow, &next);
@@ -3191,11 +3191,16 @@ static int amdgpu_device_recover_vram(struct amdgpu_device *adev)
 			break;
 
 		if (fence) {
-			r = dma_fence_wait_timeout(fence, false, tmo);
+			tmo = dma_fence_wait_timeout(fence, false, tmo);
 			dma_fence_put(fence);
 			fence = next;
-			if (r <= 0)
+			if (tmo == 0) {
+				r = -ETIMEDOUT;
 				break;
+			} else if (tmo < 0) {
+				r = tmo;
+				break;
+			}
 		} else {
 			fence = next;
 		}
@@ -3206,8 +3211,8 @@ static int amdgpu_device_recover_vram(struct amdgpu_device *adev)
 		tmo = dma_fence_wait_timeout(fence, false, tmo);
 	dma_fence_put(fence);
 
-	if (r <= 0 || tmo <= 0) {
-		DRM_ERROR("recover vram bo from shadow failed\n");
+	if (r < 0 || tmo <= 0) {
+		DRM_ERROR("recover vram bo from shadow failed, tmo is %d\n", tmo);
 		return -EIO;
 	}
 
-- 
2.7.4