[PATCH v2 2/2] drm/ttm: Add a device flag to propagate -ENOSPC on OOM

[Christian König]

Am 02.10.24 um 14:24 schrieb Thomas Hellström:
> Some graphics APIs differentiate between out-of-graphics-memory and
> out-of-host-memory (system memory). Add a device init flag to
> have -ENOSPC propagated from the resource managers instead of being
> converted to -ENOMEM, to aid driver stacks in determining what
> error code to return or whether corrective action can be taken at
> the driver level.
>
> Cc: Christian König <christian.koenig at amd.com>
> Cc: Matthew Brost <matthew.brost at intel.com>
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>

Independent of how we communicate flags to the TTM device init function 
this looks like the right approach to me.

So feel free to add Reviewed-by: Christian König <christian.koenig at amd.com>.

Regards,
Christian.

> ---
>   drivers/gpu/drm/ttm/ttm_bo.c     |  2 +-
>   drivers/gpu/drm/ttm/ttm_device.c |  1 +
>   include/drm/ttm/ttm_device.h     | 13 +++++++++++++
>   3 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 320592435252..c4bec2ad301b 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -835,7 +835,7 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
>   
>   	/* For backward compatibility with userspace */
>   	if (ret == -ENOSPC)
> -		return -ENOMEM;
> +		return bo->bdev->propagate_enospc ? ret : -ENOMEM;
>   
>   	/*
>   	 * We might need to add a TTM.
> diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
> index 0c85d10e5e0b..aee9d52d745b 100644
> --- a/drivers/gpu/drm/ttm/ttm_device.c
> +++ b/drivers/gpu/drm/ttm/ttm_device.c
> @@ -203,6 +203,7 @@ int ttm_device_init(struct ttm_device *bdev, const struct ttm_device_funcs *func
>   	}
>   
>   	bdev->funcs = funcs;
> +	bdev->propagate_enospc = flags.propagate_enospc;
>   
>   	ttm_sys_man_init(bdev);
>   
> diff --git a/include/drm/ttm/ttm_device.h b/include/drm/ttm/ttm_device.h
> index 1534bd946c78..f9da78bbd925 100644
> --- a/include/drm/ttm/ttm_device.h
> +++ b/include/drm/ttm/ttm_device.h
> @@ -266,6 +266,13 @@ struct ttm_device {
>   	 * @wq: Work queue structure for the delayed delete workqueue.
>   	 */
>   	struct workqueue_struct *wq;
> +
> +	/**
> +	 * @propagate_enospc: Whether -ENOSPC should be propagated to the caller after
> +	 * graphics memory allocation failure. If false, this will be converted to
> +	 * -ENOMEM, which is the default behaviour.
> +	 */
> +	bool propagate_enospc;
>   };
>   
>   int ttm_global_swapout(struct ttm_operation_ctx *ctx, gfp_t gfp_flags);
> @@ -295,6 +302,12 @@ struct ttm_device_init_flags {
>   	u32 use_dma_alloc : 1;
>   	/** @use_dma32: If we should use GFP_DMA32 for device memory allocations. */
>   	u32 use_dma32 : 1;
> +	/**
> +	 * @propagate_enospc: Whether -ENOSPC should be propagated to the caller after
> +	 * graphics memory allocation failure. If false, this will be converted to
> +	 * -ENOMEM, which is the default behaviour.
> +	 */
> +	u32 propagate_enospc : 1;
>   };
>   
>   int ttm_device_init(struct ttm_device *bdev, const struct ttm_device_funcs *funcs,