Re: [PATCH 07/12] drm/v3d: Size the kperfmon_ids array at runtime

[Maíra Canal <mcanal@xxxxxxxxxx>]

On 7/10/24 10:41, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>
>
> Instead of statically reserving pessimistic space for the kperfmon_ids
> array, make the userspace extension code allocate the exactly required
> amount of space.
>
> Apart from saving some memory at runtime, this also removes the need for
> the V3D_MAX_PERFMONS macro whose removal will benefit further driver
> cleanup.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>

Reviewed-by: Maíra Canal <mcanal@xxxxxxxxxx>

Best Regards,
- Maíra

> ---
>   drivers/gpu/drm/v3d/v3d_drv.h    |  6 +-----
>   drivers/gpu/drm/v3d/v3d_sched.c  |  4 +++-
>   drivers/gpu/drm/v3d/v3d_submit.c | 17 +++++++++++------
>   3 files changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h
> index 38c80168da51..00fe5d993175 100644
> --- a/drivers/gpu/drm/v3d/v3d_drv.h
> +++ b/drivers/gpu/drm/v3d/v3d_drv.h
> @@ -351,13 +351,9 @@ struct v3d_timestamp_query {
>   	struct drm_syncobj *syncobj;
>   };
>   
> -/* Number of perfmons required to handle all supported performance counters */
> -#define V3D_MAX_PERFMONS DIV_ROUND_UP(V3D_MAX_COUNTERS, \
> -				      DRM_V3D_MAX_PERF_COUNTERS)
> -
>   struct v3d_performance_query {
>   	/* Performance monitor IDs for this query */
> -	u32 kperfmon_ids[V3D_MAX_PERFMONS];
> +	u32 *kperfmon_ids;
>   
>   	/* Syncobj that indicates the query availability */
>   	struct drm_syncobj *syncobj;
> diff --git a/drivers/gpu/drm/v3d/v3d_sched.c b/drivers/gpu/drm/v3d/v3d_sched.c
> index 173801aa54ee..fc8730264386 100644
> --- a/drivers/gpu/drm/v3d/v3d_sched.c
> +++ b/drivers/gpu/drm/v3d/v3d_sched.c
> @@ -94,8 +94,10 @@ __v3d_performance_query_info_free(struct v3d_performance_query_info *qinfo,
>   	if (qinfo->queries) {
>   		unsigned int i;
>   
> -		for (i = 0; i < count; i++)
> +		for (i = 0; i < count; i++) {
>   			drm_syncobj_put(qinfo->queries[i].syncobj);
> +			kvfree(qinfo->queries[i].kperfmon_ids);
> +		}
>   
>   		kvfree(qinfo->queries);
>   	}
> diff --git a/drivers/gpu/drm/v3d/v3d_submit.c b/drivers/gpu/drm/v3d/v3d_submit.c
> index 35682433f75b..8dae3ab5f936 100644
> --- a/drivers/gpu/drm/v3d/v3d_submit.c
> +++ b/drivers/gpu/drm/v3d/v3d_submit.c
> @@ -668,10 +668,20 @@ copy_query_info(struct v3d_performance_query_info *qinfo,
>   			goto error;
>   		}
>   
> +		query->kperfmon_ids =
> +			kvmalloc_array(nperfmons,
> +				       sizeof(struct v3d_performance_query *),
> +				       GFP_KERNEL);
> +		if (!query->kperfmon_ids) {
> +			err = -ENOMEM;
> +			goto error;
> +		}
> +
>   		ids_pointer = u64_to_user_ptr(ids);
>   
>   		for (j = 0; j < nperfmons; j++) {
>   			if (get_user(id, ids_pointer++)) {
> +				kvfree(query->kperfmon_ids);
>   				err = -EFAULT;
>   				goto error;
>   			}
> @@ -681,6 +691,7 @@ copy_query_info(struct v3d_performance_query_info *qinfo,
>   
>   		query->syncobj = drm_syncobj_find(fpriv, sync);
>   		if (!query->syncobj) {
> +			kvfree(query->kperfmon_ids);
>   			err = -ENOENT;
>   			goto error;
>   		}
> @@ -714,9 +725,6 @@ v3d_get_cpu_reset_performance_params(struct drm_file *file_priv,
>   	if (copy_from_user(&reset, ext, sizeof(reset)))
>   		return -EFAULT;
>   
> -	if (reset.nperfmons > V3D_MAX_PERFMONS)
> -		return -EINVAL;
> -
>   	job->job_type = V3D_CPU_JOB_TYPE_RESET_PERFORMANCE_QUERY;
>   
>   	job->performance_query.queries = kvmalloc_array(reset.count,
> @@ -762,9 +770,6 @@ v3d_get_cpu_copy_performance_query_params(struct drm_file *file_priv,
>   	if (copy.pad)
>   		return -EINVAL;
>   
> -	if (copy.nperfmons > V3D_MAX_PERFMONS)
> -		return -EINVAL;
> -
>   	job->job_type = V3D_CPU_JOB_TYPE_COPY_PERFORMANCE_QUERY;
>   
>   	job->performance_query.queries = kvmalloc_array(copy.count,