Re: [PATCH v4 2/4] sysctl: Move some boundary constants form sysctl.c to sysctl_vals

[Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>]

On 2020/05/19 12:31, Xiaoming Ni wrote:
> Some boundary (.extra1 .extra2) constants (E.g: neg_one two) in
> sysctl.c are used in multiple features. Move these variables to
> sysctl_vals to avoid adding duplicate variables when cleaning up
> sysctls table.
> 
> Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>

I feel that it is use of

	void *extra1;
	void *extra2;

in "struct ctl_table" that requires constant values indirection.
Can't we get rid of sysctl_vals using some "union" like below?

struct ctl_table {
	const char *procname;           /* Text ID for /proc/sys, or zero */
	void *data;
	int maxlen;
	umode_t mode;
	struct ctl_table *child;        /* Deprecated */
	proc_handler *proc_handler;     /* Callback for text formatting */
	struct ctl_table_poll *poll;
	union {
		void *min_max_ptr[2];
		int min_max_int[2];
		long min_max_long[2];
	};
} __randomize_layout;