linux-kernel - Re: [PATCH v10 1/4] cgroups: use bitmask to filter for_each

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Date:	Wed, 22 Apr 2015 11:25:51 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Aleksa Sarai <cyphar@...har.com>
Cc:	lizefan@...wei.com, mingo@...hat.com, peterz@...radead.org,
	richard@....at, fweisbec@...il.com, linux-kernel@...r.kernel.org,
	cgroups@...r.kernel.org
Subject: Re: [PATCH v10 1/4] cgroups: use bitmask to filter for_each_subsys

Hello, Aleksa.

On Sun, Apr 19, 2015 at 10:22:31PM +1000, Aleksa Sarai wrote:
> -static int need_forkexit_callback __read_mostly;
> +static int need_fork_callback __read_mostly;
> +static int need_exit_callback __read_mostly;

These are bitmasks now, right?  Let's make them unsigned int.

>  static struct cftype cgroup_dfl_base_files[];
> +#define for_each_subsys_which(ss_mask, ss, ssid) \
> +	for_each_subsys((ss), (ssid)) \
> +		if ((ss_mask) & (1 << (ssid)))

Maybe using for_each_set_bit() is better?

#define for_each_subsys_which(ss_mask, ss, ssid)		\
	for_each_set_bit(ssid, &(ss_mask), CGROUP_SUBSYS_COUNT)	\
		if ((ss) = group_subsys[ssid] && false)		\
			;					\
		else

> @@ -4932,7 +4947,8 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
>  	 * init_css_set is in the subsystem's root cgroup. */
>  	init_css_set.subsys[ss->id] = css;
>  
> -	need_forkexit_callback |= ss->fork || ss->exit;
> +	need_fork_callback |= (bool) ss->fork << ss->id;
> +	need_exit_callback |= (bool) ss->exit << ss->id;
                                    ^
			  please drop the space here

Other than the above minor points, looks good to me.

Thanks for the persistence.

-- 
tejun
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