[PATCH] drm/amdgpu: add drm_dev_unplug() in GPU initialization failure to prevent crash

[Leslie Shi]

[Why]
In amdgpu_driver_load_kms, when amdgpu_device_init returns error during driver modprobe, it
will start the error handle path immediately and call into amdgpu_device_unmap_mmio as well
to release mapped VRAM. However, in the following release callback, driver stills visits the
unmapped memory like vcn.inst[i].fw_shared_cpu_addr in vcn_v3_0_sw_fini. So a kernel crash occurs.

[How]
Add drm_dev_unplug() before executing amdgpu_driver_unload_kms to prevent such crash.
GPU initialization failure is somehow allowed, but a kernel crash in this case should never happen.

Signed-off-by: Leslie Shi <Yuliang.Shi at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
index 651c7abfde03..7bf6aecdbb92 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
@@ -268,6 +268,8 @@ int amdgpu_driver_load_kms(struct amdgpu_device *adev, unsigned long flags)
 		/* balance pm_runtime_get_sync in amdgpu_driver_unload_kms */
 		if (adev->rmmio && adev->runpm)
 			pm_runtime_put_noidle(dev->dev);
+
+		drm_dev_unplug(dev);
 		amdgpu_driver_unload_kms(dev);
 	}
 
-- 
2.25.1