Re: [PATCH v4 1/2] fs/proc: optimize exactly register one ctl_table

Al Viro
2022-03-12T03:24:55Z

On Thu, Mar 03, 2022 at 03:08:46PM +0800, Meng Tang wrote:

> +#define REGISTER_SINGLE_ONE (register_single_one ? true : false)

????

> +static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header,
> + bool register_single_one)

> + err = insert_links(header, REGISTER_SINGLE_ONE);

> + erase_header(header, REGISTER_SINGLE_ONE);
> + put_links(header, REGISTER_SINGLE_ONE);

> static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table *table,
> - struct ctl_table_root *link_root)
> + struct ctl_table_root *link_root, bool register_single_one)

> + init_header(links, dir->header.root, dir->header.set, node, link_table,
> + REGISTER_SINGLE_ONE);

> -static int insert_links(struct ctl_table_header *head)
> +static int insert_links(struct ctl_table_header *head, bool register_single_one)
> {
> struct ctl_table_set *root_set = &sysctl_table_root.default_set;
> struct ctl_dir *core_parent = NULL;
> @@ -1248,13 +1278,13 @@ static int insert_links(struct ctl_table_header *head)
> if (IS_ERR(core_parent))
> return 0;
>
> - if (get_links(core_parent, head->ctl_table, head->root))
> + if (get_links(core_parent, head->ctl_table, head->root, REGISTER_SINGLE_ONE))

> - links = new_links(core_parent, head->ctl_table, head->root);
> + links = new_links(core_parent, head->ctl_table, head->root, REGISTER_SINGLE_ONE);

> + if (get_links(core_parent, head->ctl_table, head->root, REGISTER_SINGLE_ONE)) {

> + err = insert_header(core_parent, links, REGISTER_SINGLE_ONE);

> -struct ctl_table_header *__register_sysctl_table(
> +struct ctl_table_header *__register_sysctl_tables(
> struct ctl_table_set *set,
> - const char *path, struct ctl_table *table)
> + const char *path, struct ctl_table *table, bool register_single_one)

> + init_header(header, root, set, node, table, REGISTER_SINGLE_ONE);
> + if (sysctl_check_table(path, table, REGISTER_SINGLE_ONE))

> + if (insert_header(dir, header, REGISTER_SINGLE_ONE))

> static int register_leaf_sysctl_tables(const char *path, char *pos,
> struct ctl_table_header ***subheader, struct ctl_table_set *set,
> - struct ctl_table *table)
> + struct ctl_table *table, bool register_single_one)

> + header = __register_sysctl_tables(set, path, files, REGISTER_SINGLE_ONE);

Could you explain what is that REGISTER_SINGLE_ONE macro for? Looks like
some very odd kind of cargo-culting... I might be missing something subtle
here, but I'm honestly at loss as to what could that possibly be. If nothing
else, why would one ever want boolean_expression ? true : false instead of
boolean_expression? Especially since in all cases you are passing that
as a bool argument...