Re: [v4 2/5] drm/amdxcp: introduce new API amdgpu_xcp_drm_dev_free()

[Mario Limonciello <mario.limonciello@amd.com>]

On 1/9/2025 20:08, Jiang Liu wrote:
> Introduce new interface amdgpu_xcp_drm_dev_free() to free a specific
> drm_device crreated by amdgpu_xcp_drm_dev_alloc(), which will be used
s/crreated/created/
> to do error recovery.
> 
> Signed-off-by: Jiang Liu <gerry@linux.alibaba.com>
> ---
>   drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.c | 65 +++++++++++++++++----
>   drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.h |  1 +
>   2 files changed, 56 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.c b/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.c
> index faed84172dd4..0473fe0479d9 100644
> --- a/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.c
> +++ b/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.c
> @@ -45,18 +45,26 @@ static const struct drm_driver amdgpu_xcp_driver = {
>   
>   static int8_t pdev_num;
>   static struct xcp_device *xcp_dev[MAX_XCP_PLATFORM_DEVICE];
> +static DEFINE_MUTEX(xcp_mutex);
>   
>   int amdgpu_xcp_drm_dev_alloc(struct drm_device **ddev)
>   {
>   	struct platform_device *pdev;
>   	struct xcp_device *pxcp_dev;
>   	char dev_name[20];
> -	int ret;
> +	int ret, index;
> +
> +	guard(mutex)(&xcp_mutex);
>   
>   	if (pdev_num >= MAX_XCP_PLATFORM_DEVICE)
>   		return -ENODEV;
>   
> -	snprintf(dev_name, sizeof(dev_name), "amdgpu_xcp_%d", pdev_num);
> +	for (index = 0; index < MAX_XCP_PLATFORM_DEVICE; index++) {
> +		if (!xcp_dev[index])
> +			break;
> +	}
> +
> +	snprintf(dev_name, sizeof(dev_name), "amdgpu_xcp_%d", index);
>   	pdev = platform_device_register_simple(dev_name, -1, NULL, 0);
>   	if (IS_ERR(pdev))
>   		return PTR_ERR(pdev);
> @@ -72,8 +80,8 @@ int amdgpu_xcp_drm_dev_alloc(struct drm_device **ddev)
>   		goto out_devres;
>   	}
>   
> -	xcp_dev[pdev_num] = pxcp_dev;
> -	xcp_dev[pdev_num]->pdev = pdev;
> +	xcp_dev[index] = pxcp_dev;
> +	xcp_dev[index]->pdev = pdev;
>   	*ddev = &pxcp_dev->drm;
>   	pdev_num++;
>   
> @@ -88,16 +96,53 @@ int amdgpu_xcp_drm_dev_alloc(struct drm_device **ddev)
>   }
>   EXPORT_SYMBOL(amdgpu_xcp_drm_dev_alloc);
>   
> +static void __amdgpu_xcp_drm_dev_free(int index)
> +{
> +	struct platform_device *pdev;
> +

Would it be valuable to have WARN_ON(!pdev_num) here?

> +	pdev = xcp_dev[index]->pdev;
> +	devres_release_group(&pdev->dev, NULL);
> +	platform_device_unregister(pdev);
> +	xcp_dev[index] = NULL;
> +	pdev_num--;
> +}
> +
> +void amdgpu_xcp_drm_dev_free(struct drm_device *ddev)
> +{
> +	int index;
> +	struct xcp_device *pxcp_dev;

Just a nit; this should be reverse xmas tree order.

> +
> +	if (ddev == NULL)
> +		return;
> +
> +	guard(mutex)(&xcp_mutex);
> +	WARN_ON(!pdev_num);
> +
> +	pxcp_dev = container_of(ddev, struct xcp_device, drm);
> +	for (index = 0; index < MAX_XCP_PLATFORM_DEVICE; index++) {
> +		if (xcp_dev[index] == pxcp_dev) {
> +			__amdgpu_xcp_drm_dev_free(index);
> +			break;
> +		}
> +	}
> +}
> +EXPORT_SYMBOL(amdgpu_xcp_drm_dev_free);
> +
>   void amdgpu_xcp_drv_release(void)
>   {
> -	for (--pdev_num; pdev_num >= 0; --pdev_num) {
> -		struct platform_device *pdev = xcp_dev[pdev_num]->pdev;
> +	int index;
>   
> -		devres_release_group(&pdev->dev, NULL);
> -		platform_device_unregister(pdev);
> -		xcp_dev[pdev_num] = NULL;
> +	guard(mutex)(&xcp_mutex);
> +
> +	for (index = 0; index < MAX_XCP_PLATFORM_DEVICE; index++) {
> +		if (xcp_dev[index]) {
> +			__amdgpu_xcp_drm_dev_free(index);
> +			if (!pdev_num)
> +				break;
> +		}
>   	}
> -	pdev_num = 0;
> +
> +	WARN_ON(pdev_num != 0);
>   }
>   EXPORT_SYMBOL(amdgpu_xcp_drv_release);
>   
> diff --git a/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.h b/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.h
> index c1c4b679bf95..580a1602c8e3 100644
> --- a/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.h
> +++ b/drivers/gpu/drm/amd/amdxcp/amdgpu_xcp_drv.h
> @@ -25,5 +25,6 @@
>   #define _AMDGPU_XCP_DRV_H_
>   
>   int amdgpu_xcp_drm_dev_alloc(struct drm_device **ddev);
> +void amdgpu_xcp_drm_dev_free(struct drm_device *ddev);
>   void amdgpu_xcp_drv_release(void);
>   #endif /* _AMDGPU_XCP_DRV_H_ */