drm/amd/display: fix double free issue during amdgpu module unload

drm/amd/display: fix double free issue during amdgpu module unload

commit 20b5a8f9f4670a8503aa9fa95ca632e77c6bf55d upstream.

Flexible endpoints use DIGs from available inflexible endpoints,
so only the encoders of inflexible links need to be freed.
Otherwise, a double free issue may occur when unloading the
amdgpu module.

[  279.190523] RIP: 0010:__slab_free+0x152/0x2f0
[  279.190577] Call Trace:
[  279.190580]  <TASK>
[  279.190582]  ? show_regs+0x69/0x80
[  279.190590]  ? die+0x3b/0x90
[  279.190595]  ? do_trap+0xc8/0xe0
[  279.190601]  ? do_error_trap+0x73/0xa0
[  279.190605]  ? __slab_free+0x152/0x2f0
[  279.190609]  ? exc_invalid_op+0x56/0x70
[  279.190616]  ? __slab_free+0x152/0x2f0
[  279.190642]  ? asm_exc_invalid_op+0x1f/0x30
[  279.190648]  ? dcn10_link_encoder_destroy+0x19/0x30 [amdgpu]
[  279.191096]  ? __slab_free+0x152/0x2f0
[  279.191102]  ? dcn10_link_encoder_destroy+0x19/0x30 [amdgpu]
[  279.191469]  kfree+0x260/0x2b0
[  279.191474]  dcn10_link_encoder_destroy+0x19/0x30 [amdgpu]
[  279.191821]  link_destroy+0xd7/0x130 [amdgpu]
[  279.192248]  dc_destruct+0x90/0x270 [amdgpu]
[  279.192666]  dc_destroy+0x19/0x40 [amdgpu]
[  279.193020]  amdgpu_dm_fini+0x16e/0x200 [amdgpu]
[  279.193432]  dm_hw_fini+0x26/0x40 [amdgpu]
[  279.193795]  amdgpu_device_fini_hw+0x24c/0x400 [amdgpu]
[  279.194108]  amdgpu_driver_unload_kms+0x4f/0x70 [amdgpu]
[  279.194436]  amdgpu_pci_remove+0x40/0x80 [amdgpu]
[  279.194632]  pci_device_remove+0x3a/0xa0
[  279.194638]  device_remove+0x40/0x70
[  279.194642]  device_release_driver_internal+0x1ad/0x210
[  279.194647]  driver_detach+0x4e/0xa0
[  279.194650]  bus_remove_driver+0x6f/0xf0
[  279.194653]  driver_unregister+0x33/0x60
[  279.194657]  pci_unregister_driver+0x44/0x90
[  279.194662]  amdgpu_exit+0x19/0x1f0 [amdgpu]
[  279.194939]  __do_sys_delete_module.isra.0+0x198/0x2f0
[  279.194946]  __x64_sys_delete_module+0x16/0x20
[  279.194950]  do_syscall_64+0x58/0x120
[  279.194954]  entry_SYSCALL_64_after_hwframe+0x6e/0x76
[  279.194980]  </TASK>

Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Tim Huang <tim.huang@amd.com>
Reviewed-by: Roman Li <roman.li@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[ dc_link_destruct() moved from core/dc_link.c to link/link_factory.c since
commit: 54618888d1ea ("drm/amd/display: break down dc_link.c"), so modified
the path to apply on 5.15.y ]
Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com>
Signed-off-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>