[PATCH 1/2] drm: Add GPU reset sysfs event

[Christian König]

Am 07.03.22 um 17:26 schrieb Shashank Sharma:
> From: Shashank Sharma <shashank.sharma at amd.com>
>
> This patch adds a new sysfs event, which will indicate
> the userland about a GPU reset, and can also provide
> some information like:
> - which PID was involved in the GPU reset
> - what was the GPU status (using flags)
>
> This patch also introduces the first flag of the flags
> bitmap, which can be appended as and when required.

Make sure to CC the dri-devel mailing list when reviewing this.

>
> Cc: Alexandar Deucher <alexander.deucher at amd.com>
> Cc: Christian Koenig <christian.koenig at amd.com>
> Signed-off-by: Shashank Sharma <shashank.sharma at amd.com>
> ---
>   drivers/gpu/drm/drm_sysfs.c | 24 ++++++++++++++++++++++++
>   include/drm/drm_sysfs.h     |  3 +++
>   2 files changed, 27 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
> index 430e00b16eec..52a015161431 100644
> --- a/drivers/gpu/drm/drm_sysfs.c
> +++ b/drivers/gpu/drm/drm_sysfs.c
> @@ -409,6 +409,30 @@ void drm_sysfs_hotplug_event(struct drm_device *dev)
>   }
>   EXPORT_SYMBOL(drm_sysfs_hotplug_event);
>   
> +/**
> + * drm_sysfs_reset_event - generate a DRM uevent to indicate GPU reset
> + * @dev: DRM device
> + * @pid: The process ID involve with the reset
> + * @flags: Any other information about the GPU status
> + *
> + * Send a uevent for the DRM device specified by @dev. This indicates
> + * user that a GPU reset has occurred, so that the interested client
> + * can take any recovery or profiling measure, when required.
> + */
> +void drm_sysfs_reset_event(struct drm_device *dev, uint64_t pid, uint32_t flags)

The PID is usually only 32bit, but even better would be to use pid_t.

> +{
> +	unsigned char pid_str[21], flags_str[15];
> +	unsigned char reset_str[] = "RESET=1";
> +	char *envp[] = { reset_str, pid_str, flags_str, NULL };
> +
> +	DRM_DEBUG("generating reset event\n");
> +
> +	snprintf(pid_str, ARRAY_SIZE(pid_str), "PID=%lu", pid);
> +	snprintf(flags_str, ARRAY_SIZE(flags_str), "FLAGS=%u", flags);
> +	kobject_uevent_env(&dev->primary->kdev->kobj, KOBJ_CHANGE, envp);
> +}
> +EXPORT_SYMBOL(drm_sysfs_reset_event);
> +
>   /**
>    * drm_sysfs_connector_hotplug_event - generate a DRM uevent for any connector
>    * change
> diff --git a/include/drm/drm_sysfs.h b/include/drm/drm_sysfs.h
> index 6273cac44e47..63f00fe8054c 100644
> --- a/include/drm/drm_sysfs.h
> +++ b/include/drm/drm_sysfs.h
> @@ -2,6 +2,8 @@
>   #ifndef _DRM_SYSFS_H_
>   #define _DRM_SYSFS_H_
>   
> +#define DRM_GPU_RESET_FLAG_VRAM_VALID (1 << 0)

Probably better to define that the other way around, e.g. 
DRM_GPU_RESET_FLAG_VRAM_LOST.

Apart from that looks good to me.

Christian.

> +
>   struct drm_device;
>   struct device;
>   struct drm_connector;
> @@ -11,6 +13,7 @@ int drm_class_device_register(struct device *dev);
>   void drm_class_device_unregister(struct device *dev);
>   
>   void drm_sysfs_hotplug_event(struct drm_device *dev);
> +void drm_sysfs_reset_event(struct drm_device *dev, uint64_t pid, uint32_t reset_flags);
>   void drm_sysfs_connector_hotplug_event(struct drm_connector *connector);
>   void drm_sysfs_connector_status_event(struct drm_connector *connector,
>   				      struct drm_property *property);