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

[Sharma, Shashank]

On 3/8/2022 8:06 AM, Christian König wrote:
> 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.
Got it,

I was also curious if we want to move the reset_ctx structure itself to 
DRM layer, like
drm_reset_event_ctx {
	u32 pid;
	u32 flags;
	char process_name[64];
};

and then:
void drm_sysfs_reset_event(struct drm_device *dev, drm_reset_event_ctx 
*ctx);

> 
>>
>> 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.
> 
Got it, noted.
- Shashank

> 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);
>