Re: [PATCH v4 1/9] drm/xe: Add a new xe_user structure

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Sep 26, 2025 at 10:45:12AM +0000, Aakash Deep Sarkar wrote:
> For Android GPU work period event we need to track the runtime
> on the GPU for each user id. This means we can have multiple
> xe files opened by different processes/threads belonging to
> the same user id. All these xe files need to be grouped together
> so that one can easily identify these while calculating the
> run time for the given user id.
> 
> Currently, the xe driver doesn't record the user id of the
> calling process. Also, all the xe files created using open
> call are clubbed together inside the xe device structure
> with no way to distinguish between them based on the user id
> of the calling process.
> 
> To remedy these limitations we are adding another layer of
> indirection between xe device and xe file. xe device will
> now have a list of xe users each with a given user id; and each
> xe user will have a list of xe files each of which is created
> by a process that is associated with this user id.
> 
> The lifetime of the xe user structure should be between when
> a process with a new user id has opened the xe device; and when
> the last xe file belonging to this user id is closed.
> 
> Signed-off-by: Aakash Deep Sarkar <aakash.deep.sarkar@intel.com>
> ---
>  drivers/gpu/drm/xe/Makefile  |  2 +
>  drivers/gpu/drm/xe/xe_user.c | 59 ++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_user.h | 81 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 142 insertions(+)
>  create mode 100644 drivers/gpu/drm/xe/xe_user.c
>  create mode 100644 drivers/gpu/drm/xe/xe_user.h
> 
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index d9c6cf0f189e..ff6b584f3293 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -333,6 +333,8 @@ ifeq ($(CONFIG_DEBUG_FS),y)
>  
>  	xe-$(CONFIG_PCI_IOV) += xe_gt_sriov_pf_debugfs.o
>  
> +	xe-y += xe_user.o
> +
>  	xe-$(CONFIG_DRM_XE_DISPLAY) += \
>  		i915-display/intel_display_debugfs.o \
>  		i915-display/intel_display_debugfs_params.o \
> diff --git a/drivers/gpu/drm/xe/xe_user.c b/drivers/gpu/drm/xe/xe_user.c
> new file mode 100644
> index 000000000000..8c285a68115a
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_user.c
> @@ -0,0 +1,59 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2023 Intel Corporation

2025

> + */
> +
> +#include <linux/slab.h>
> +
> +#include "xe_user.h"
> +

Please add a /** DOC: 
section in here explaining the xe_user. Mostly adapted from the commit
message above, but no need to mention Android. Just mention that this
is aimed to track different users, like the message explains

> +/**
> + * worker thread to emit gpu work period event for this xe user
> + * @work: work instance for this xe user
> + *
> + * Return: void
> + */

no kernel doc in static functions


> +static inline void work_period_worker(struct work_struct *work)
> +{
> +	//TODO: Implement this worker

Perhaps you should not add this stub here and wait to add in
the next patches along with the implementation.

> +}
> +
> +/**
> + * xe_user_alloc() - Allocate xe user
> + * @void: No arg
> + *
> + * Allocate xe user struct to track activity on the gpu
> + * by the application. Call this API whenever a new app
> + * has opened xe device.
> + *
> + * Return: pointer to user struct or NULL if can't allocate
> + */
> +struct xe_user *xe_user_alloc(void)
> +{
> +	struct xe_user *user;
> +
> +	user = kzalloc(sizeof(*user), GFP_KERNEL);
> +	if (!user)
> +		return NULL;
> +
> +	kref_init(&user->refcount);
> +	mutex_init(&user->filelist_lock);
> +	INIT_LIST_HEAD(&user->filelist);
> +	//TODO: Add a hook into xe device

probably better to not add the TODO things at all, specially
if you are adding this in this series.

> +	INIT_WORK(&user->work, work_period_worker);
> +	return user;
> +}
> +
> +/**
> + * __xe_user_free() - Free user struct
> + * @kref: The reference
> + *
> + * Return: void
> + */
> +void __xe_user_free(struct kref *kref)
> +{
> +	struct xe_user *user =
> +		container_of(kref, struct xe_user, refcount);
> +
> +	kfree(user);
> +}
> diff --git a/drivers/gpu/drm/xe/xe_user.h b/drivers/gpu/drm/xe/xe_user.h
> new file mode 100644
> index 000000000000..e52f66d3f3b0
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_user.h
> @@ -0,0 +1,81 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2023 Intel Corporation

2025

> + */
> +
> +#ifndef _XE_USER_H_
> +#define _XE_USER_H_
> +
> +#include <linux/kref.h>
> +#include <linux/list.h>
> +#include <linux/workqueue.h>
> +
> +/**
> + * This is a per process/user id structure for a xe device

probably not following the doc standards here...

> + * client. It is allocated when a new process/app opens the
> + * xe device and destroyed when the last xe file belonging
> + * to this user id is destroyed.
> + */
> +struct xe_user {
> +	/**
> +	 * @refcount: reference count
> +	 */
> +	struct kref refcount;
> +
> +	/**
> +	 * @xe: pointer to the xe_device
> +	 */
> +	struct xe_device *xe;
> +
> +	/**
> +	 * @filelist_lock: lock protecting the filelist
> +	 */
> +	struct mutex filelist_lock;
> +
> +	/**
> +	 * @filelist: list of xe files belonging to this xe user
> +	 */
> +	struct list_head filelist;
> +
> +	/**
> +	 * @work: work to emit the gpu work period event for this
> +	 * xe user
> +	 */
> +	struct work_struct work;
> +
> +	/**
> +	 * @uid: user id for this xe_user
> +	 */
> +	u32 uid;
> +
> +	/**
> +	 * @active_duration_ns: sum total of xe_file.active_duration_ns
> +	 * for all xe files belonging to this xe user
> +	 */
> +	u64 active_duration_ns;
> +
> +	/**
> +	 * @last_timestamp_ns: timestamp in ns when we last emitted event
> +	 * for this xe user
> +	 */
> +	u64 last_timestamp_ns;
> +};
> +
> +struct xe_user *xe_user_alloc(void);
> +
> +static inline struct xe_user *
> +xe_user_get(struct xe_user *user)
> +{
> +	kref_get(&user->refcount);
> +	return user;
> +}
> +
> +void __xe_user_free(struct kref *kref);
> +
> +static inline void xe_user_put(struct xe_user *user)
> +{
> +	kref_put(&user->refcount, __xe_user_free);
> +}
> +
> +#endif // _XE_USER_H_
> +
> -- 
> 2.49.0
>