[PATCH] drm/amdgpu: add missed write lock for pci detected state pci_channel_io_normal

[Chen, Guchun]

[Public]

Hi Andrey,

Do you mean to move the code of drm_sched_resubmit_jobs and drm_sched_start in amdgpu_pci_resume to amdgpu_pci_error_detected, under the case pci_channel_io_frozen?
Then leave amdgpu_pci_resume as a null function, and in this way, we can drop the acquire/lock write lock for case of pci_channel_io_normal as well?

Regards,
Guchun

-----Original Message-----
From: Grodzovsky, Andrey <Andrey.Grodzovsky at amd.com> 
Sent: Friday, October 1, 2021 10:22 AM
To: Chen, Guchun <Guchun.Chen at amd.com>; amd-gfx at lists.freedesktop.org; Koenig, Christian <Christian.Koenig at amd.com>; Pan, Xinhui <Xinhui.Pan at amd.com>; Deucher, Alexander <Alexander.Deucher at amd.com>
Subject: Re: [PATCH] drm/amdgpu: add missed write lock for pci detected state pci_channel_io_normal

On 2021-09-30 10:00 p.m., Guchun Chen wrote:

> 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.


Good catch but, the issue is even wider in scope, what about drm_sched_resubmit_jobs and drm_sched_start called without being stopped before ? Better to put the entire scope of code in this function under flag that set only in pci_channel_io_frozen. As far as i remember we don't need to do anything in case of pci_channel_io_normal.

Andrey


>
> Fixes: c9a6b82f45e2("drm/amdgpu: Implement DPC recovery")
> Signed-off-by: Guchun Chen <guchun.chen at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index bb5ad2b6ca13..12f822d51de2 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -5370,6 +5370,7 @@ pci_ers_result_t 
> amdgpu_pci_error_detected(struct pci_dev *pdev, pci_channel_sta
>   
>   	switch (state) {
>   	case pci_channel_io_normal:
> +		amdgpu_device_lock_adev(adev, NULL);
>   		return PCI_ERS_RESULT_CAN_RECOVER;
>   	/* Fatal error, prepare for slot reset */
>   	case pci_channel_io_frozen: