Coverity: amdgpu_dm_fini(): Null pointer dereferences

Hello!

This is an experimental automated report about issues detected by Coverity from a scan of next-20191108 as part of the linux-next weekly scan project:
https://scan.coverity.com/projects/linux-next-weekly-scan

You're getting this email because you were associated with the identified lines of code (noted below) that were touched by recent commits:

c9dc20afe70a ("drm/amd/display: Register DMUB service with DC")

Coverity reported the following:

*** CID 1487836: Null pointer dereferences (FORWARD_NULL) /drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c: 1037 in amdgpu_dm_fini()
1031 adev->dm.hdcp_workqueue = NULL;
1032 }
1033

1034     	if (adev->dm.dc)
1035     		dc_deinit_callbacks(adev->dm.dc);
1036     #endif
vvv     CID 1487836:  Null pointer dereferences  (FORWARD_NULL)
vvv     Dereferencing null pointer "adev->dm.dc".
1037     	if (adev->dm.dc->ctx->dmub_srv) {
1038     		dc_dmub_srv_destroy(&adev->dm.dc->ctx->dmub_srv);
1039     		adev->dm.dc->ctx->dmub_srv = NULL;
1040     	}

1041
1042 if (adev->dm.dmub_bo)

If this is a false positive, please let us know so we can mark it as such, or teach the Coverity rules to be smarter. If not, please make sure fixes get into linux-next. :) For patches fixing this, please include these lines (but double-check the "Fixes" first):

Addresses-Coverity-ID: 1487836 ("Null pointer dereferences")

Thanks for your attention!

Coverity-bot