On 2021-10-02 11:18 a.m., Guchun Chen wrote:
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. Fixes: c9a6b82f45e2("drm/amdgpu: Implement DPC recovery") Suggested-by: Andrey Grodzovsky <andrey.grodzov...@amd.com> Signed-off-by: Guchun Chen <guchun.c...@amd.com> --- drivers/gpu/drm/amd/amdgpu/amdgpu.h | 1 + drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 6 ++++++ 2 files changed, 7 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h index f4bceb2624fb..720d0ccecfe0 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h @@ -1094,6 +1094,7 @@ struct amdgpu_device {bool no_hw_access;struct pci_saved_state *pci_state; + pci_channel_state_t cached_state;
I would give a more descriptive name to this (e.g. pci_channel_state) Other then that Reviewed-by: Andrey Grodzovsky <andrey.grodzov...@amd.com> Andrey
struct amdgpu_reset_control *reset_cntl;uint32_t ip_versions[HW_ID_MAX][HWIP_MAX_INSTANCE]; diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c index bb5ad2b6ca13..1aaeb4b30edc 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c @@ -5368,6 +5368,8 @@ pci_ers_result_t amdgpu_pci_error_detected(struct pci_dev *pdev, pci_channel_sta return PCI_ERS_RESULT_DISCONNECT; }+ adev->cached_state = state;+ switch (state) { case pci_channel_io_normal: return PCI_ERS_RESULT_CAN_RECOVER; @@ -5510,6 +5512,10 @@ void amdgpu_pci_resume(struct pci_dev *pdev)DRM_INFO("PCI error: resume callback!!\n"); + /* Only continue execution for the case of pci_channel_io_frozen */+ if (adev->cached_state != pci_channel_io_frozen) + return; + for (i = 0; i < AMDGPU_MAX_RINGS; ++i) { struct amdgpu_ring *ring = adev->rings[i];
