drm/amdgpu: handle wrap around in reemit handling

Compare the sequence numbers directly.

Fixes: 77cc0da ("drm/amdgpu: track ring state associated with a fence")
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: alexdeucher

drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c

@@ -790,14 +790,19 @@ void amdgpu_ring_backup_unprocessed_commands(struct amdgpu_ring *ring,
 	struct dma_fence *unprocessed;
 	struct dma_fence __rcu **ptr;
 	struct amdgpu_fence *fence;
-	u64 wptr, i, seqno;
+	u64 wptr;
+	u32 seq, last_seq;
 
-	seqno = amdgpu_fence_read(ring);
+	last_seq = amdgpu_fence_read(ring) & ring->fence_drv.num_fences_mask;
+	seq = ring->fence_drv.sync_seq & ring->fence_drv.num_fences_mask;
 	wptr = ring->fence_drv.signalled_wptr;
 	ring->ring_backup_entries_to_copy = 0;
 
-	for (i = seqno + 1; i <= ring->fence_drv.sync_seq; ++i) {
-		ptr = &ring->fence_drv.fences[i & ring->fence_drv.num_fences_mask];
+	do {
+		last_seq++;
+		last_seq &= ring->fence_drv.num_fences_mask;
+
+		ptr = &ring->fence_drv.fences[last_seq];
 		rcu_read_lock();
 		unprocessed = rcu_dereference(*ptr);
 
@@ -813,7 +818,7 @@ void amdgpu_ring_backup_unprocessed_commands(struct amdgpu_ring *ring,
 			wptr = fence->wptr;
 		}
 		rcu_read_unlock();
-	}
+	} while (last_seq != seq);
 }
 
 /*