CVE-2021-47421

In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: handle the case of pci_channel_io_frozen only in
amdgpu_pci_resume In current code, when a PCI error state
pci_channel_io_normal is detectd, it will report PCI_ERS_RESULT_CAN_RECOVER
status to PCI driver, and PCI driver will continue the execution of PCI
resume callback report_resume by pci_walk_bridge, and the callback will go
into amdgpu_pci_resume finally, where write lock is releasd unconditionally
without acquiring such lock first. In this case, a deadlock will happen
when other threads start to acquire the read lock. To fix this, add a
member in amdgpu_device strucutre to cache pci_channel_state, and only
continue the execution in amdgpu_pci_resume when it’s
pci_channel_io_frozen.