Re: [PATCH v2 -next 1/3] mm/hugetlb_cgroup: identify the legacy using cgroup_subsys_on_dfl()

[Oscar Salvador <osalvador@suse.de>]

On Wed, Jun 05, 2024 at 07:01:31AM +0000, Xiu Jianfeng wrote:
> Currently the numa_stat file encodes 1 into private using the micro
> MEMFILE_PRIVATE() to identify the legacy. Actually, we can use
> cgroup_subsys_on_dfl() instead. This is helpful to handle .private
> in the static array of the comming patch.
> 
> Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>

Reviewed-by: Oscar Salvador <osalvador@suse.de>

Nit below:

> ---
>  mm/hugetlb_cgroup.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> index e20339a346b9..45f94a869776 100644
> --- a/mm/hugetlb_cgroup.c
> +++ b/mm/hugetlb_cgroup.c
> @@ -460,7 +460,7 @@ static int hugetlb_cgroup_read_numa_stat(struct seq_file *seq, void *dummy)
>  	int nid;
>  	struct cftype *cft = seq_cft(seq);
>  	int idx = MEMFILE_IDX(cft->private);
> -	bool legacy = MEMFILE_ATTR(cft->private);
> +	bool legacy = !cgroup_subsys_on_dfl(hugetlb_cgrp_subsys);
>  	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(seq_css(seq));
>  	struct cgroup_subsys_state *css;
>  	unsigned long usage;
> @@ -839,7 +839,7 @@ static void __init __hugetlb_cgroup_file_legacy_init(int idx)
>  	/* Add the numa stat file */
>  	cft = &h->cgroup_files_legacy[8];
>  	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.numa_stat", buf);
> -	cft->private = MEMFILE_PRIVATE(idx, 1);
> +	cft->private = MEMFILE_PRIVATE(idx, 0);

Do we still have to set it to '0'?
Is it not by default?

-- 
Oscar Salvador
SUSE Labs