[PATCH v2] amdgpu_dm: add missing NULL checks in amdgpu_dm_fini()

[Daniil Tatianin]

adev->dm.dc is already checked in a few other if branches of the same
function so no reason not to check it everywhere else as well.

Moreover, admgpu_dm_fini() can be called from an error branch in
amdgpu_dm_init(), at which point it won't contain a valid dm.dc.
This might happen, for example, under OOM conditions.

Found by Linux Verification Center (linuxtesting.org) with the SVACE
static analysis tool.

Signed-off-by: Daniil Tatianin <d-tatianin at yandex-team.ru>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 589bee9acf16..6992bf766009 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1716,7 +1716,8 @@ static void amdgpu_dm_fini(struct amdgpu_device *adev)
 		dc_deinit_callbacks(adev->dm.dc);
 #endif
 
-	dc_dmub_srv_destroy(&adev->dm.dc->ctx->dmub_srv);
+	if (adev->dm.dc)
+		dc_dmub_srv_destroy(&adev->dm.dc->ctx->dmub_srv);
 
 	if (dc_enable_dmub_notifications(adev->dm.dc)) {
 		kfree(adev->dm.dmub_notify);
@@ -1731,7 +1732,9 @@ static void amdgpu_dm_fini(struct amdgpu_device *adev)
 				      &adev->dm.dmub_bo_cpu_addr);
 
 	if (adev->dm.hpd_rx_offload_wq) {
-		for (i = 0; i < adev->dm.dc->caps.max_links; i++) {
+		int max_links = adev->dm.dc ? adev->dm.dc->caps.max_links : 0;
+
+		for (i = 0; i < max_links; i++) {
 			if (adev->dm.hpd_rx_offload_wq[i].wq) {
 				destroy_workqueue(adev->dm.hpd_rx_offload_wq[i].wq);
 				adev->dm.hpd_rx_offload_wq[i].wq = NULL;
-- 
2.25.1