[bug report] drm/amdgpu/mes: ring aggregatged doorbell when mes queue is unmapped

[Dan Carpenter]

Hello Le Ma,

The patch 5fdbff096edb: "drm/amdgpu/mes: ring aggregatged doorbell
when mes queue is unmapped" from Oct 30, 2020, leads to the following
unpublished Smatch static checker warning:

	drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c:8552 gfx_v10_0_ring_set_wptr_gfx()
	warn: duplicate check '*is_queue_unmap' (previous on line 8546)

drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
    8525 static void gfx_v10_0_ring_set_wptr_gfx(struct amdgpu_ring *ring)
    8526 {
    8527         struct amdgpu_device *adev = ring->adev;
    8528         uint32_t *wptr_saved;
    8529         uint32_t *is_queue_unmap;
    8530         uint64_t aggregated_db_index;
    8531         uint32_t mqd_size = adev->mqds[AMDGPU_HW_IP_GFX].mqd_size;
    8532         uint64_t wptr_tmp;
    8533 
    8534         if (ring->is_mes_queue) {
    8535                 wptr_saved = (uint32_t *)(ring->mqd_ptr + mqd_size);
    8536                 is_queue_unmap = (uint32_t *)(ring->mqd_ptr + mqd_size +
    8537                                               sizeof(uint32_t));
    8538                 aggregated_db_index =
    8539                         amdgpu_mes_get_aggregated_doorbell_index(adev,
    8540                         AMDGPU_MES_PRIORITY_LEVEL_NORMAL);
    8541 
    8542                 wptr_tmp = ring->wptr & ring->buf_mask;
    8543                 atomic64_set((atomic64_t *)ring->wptr_cpu_addr, wptr_tmp);
    8544                 *wptr_saved = wptr_tmp;
    8545                 /* assume doorbell always being used by mes mapped queue */
    8546                 if (*is_queue_unmap) {
                             ^^^^^^^^^^^^^^^

Checked

    8547                         WDOORBELL64(aggregated_db_index, wptr_tmp);
    8548                         WDOORBELL64(ring->doorbell_index, wptr_tmp);
    8549                 } else {
    8550                         WDOORBELL64(ring->doorbell_index, wptr_tmp);
    8551 
--> 8552                         if (*is_queue_unmap)
                                     ^^^^^^^^^^^^^^^

It's possible this is changed inside a function, but it looks suspicious.

    8553                                 WDOORBELL64(aggregated_db_index, wptr_tmp);
    8554                 }
    8555         } else {
    8556                 if (ring->use_doorbell) {
    8557                         /* XXX check if swapping is necessary on BE */
    8558                         atomic64_set((atomic64_t *)ring->wptr_cpu_addr,
    8559                                      ring->wptr);
    8560                         WDOORBELL64(ring->doorbell_index, ring->wptr);
    8561                 } else {
    8562                         WREG32_SOC15(GC, 0, mmCP_RB0_WPTR,
    8563                                      lower_32_bits(ring->wptr));
    8564                         WREG32_SOC15(GC, 0, mmCP_RB0_WPTR_HI,
    8565                                      upper_32_bits(ring->wptr));
    8566                 }
    8567         }
    8568 }

regards,
dan carpenter