From: Guchun Chen guchun.chen@amd.com

[ Upstream commit 248b061689a40f4fed05252ee2c89f87cf26d7d8 ]

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.grodzovsky@amd.com Signed-off-by: Guchun Chen guchun.chen@amd.com Reviewed-by: Andrey Grodzovsky andrey.grodzovsky@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org [Shivani: Modified to apply on 5.10.y] Signed-off-by: Shivani Agarwal shivani.agarwal@broadcom.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 ff5555353eb4..683bbefc39c1 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h @@ -997,6 +997,7 @@ struct amdgpu_device {

bool in_pci_err_recovery; struct pci_saved_state *pci_state; + pci_channel_state_t pci_channel_state; };

static inline struct amdgpu_device *drm_to_adev(struct drm_device *ddev) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c index 40d2f0ed1c75..8efd3ee2621f 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c @@ -4944,6 +4944,8 @@ pci_ers_result_t amdgpu_pci_error_detected(struct pci_dev *pdev, pci_channel_sta return PCI_ERS_RESULT_DISCONNECT; }

+ adev->pci_channel_state = state; + switch (state) { case pci_channel_io_normal: return PCI_ERS_RESULT_CAN_RECOVER; @@ -5079,6 +5081,10 @@ 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->pci_channel_state != pci_channel_io_frozen) + return; + for (i = 0; i < AMDGPU_MAX_RINGS; ++i) { struct amdgpu_ring *ring = adev->rings[i];