Re: [PATCH 1/4] cgroup: convert cgroupfs_root flag bits to masks and add CGRP_ prefix

[Serge Hallyn <serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>]

Quoting Tejun Heo (tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org):
> There's no reason to be using bitops, which tends to be more
> cumbersome, to handle root flags.  Convert them to masks.  Also, as
> they'll be moved to include/linux/cgroup.h and it's generally a good
> idea, add CGRP_ prefix.
> 
> Note that flags are assigned from (1 << 1).  The first bit will be
> used by a flag which will be added soon.
> 
> Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

This *is* much nicer to read, thanks.

Acked-by: Serge E. Hallyn <serge.hallyn-GeWIH/nMZzLQT0dZR+AlfA@public.gmane.org>

> ---
>  kernel/cgroup.c | 21 ++++++++++-----------
>  1 file changed, 10 insertions(+), 11 deletions(-)
> 
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 678a22c..a372eaa 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -296,10 +296,10 @@ bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor)
>  }
>  EXPORT_SYMBOL_GPL(cgroup_is_descendant);
>  
> -/* bits in struct cgroupfs_root flags field */
> +/* cgroupfs_root->flags */
>  enum {
> -	ROOT_NOPREFIX,	/* mounted subsystems have no named prefix */
> -	ROOT_XATTR,	/* supports extended attributes */
> +	CGRP_ROOT_NOPREFIX	= (1 << 1), /* mounted subsystems have no named prefix */
> +	CGRP_ROOT_XATTR		= (1 << 2), /* supports extended attributes */
>  };
>  
>  static int cgroup_is_releasable(const struct cgroup *cgrp)
> @@ -1137,9 +1137,9 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry)
>  	mutex_lock(&cgroup_root_mutex);
>  	for_each_subsys(root, ss)
>  		seq_printf(seq, ",%s", ss->name);
> -	if (test_bit(ROOT_NOPREFIX, &root->flags))
> +	if (root->flags & CGRP_ROOT_NOPREFIX)
>  		seq_puts(seq, ",noprefix");
> -	if (test_bit(ROOT_XATTR, &root->flags))
> +	if (root->flags & CGRP_ROOT_XATTR)
>  		seq_puts(seq, ",xattr");
>  	if (strlen(root->release_agent_path))
>  		seq_printf(seq, ",release_agent=%s", root->release_agent_path);
> @@ -1202,7 +1202,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
>  			continue;
>  		}
>  		if (!strcmp(token, "noprefix")) {
> -			set_bit(ROOT_NOPREFIX, &opts->flags);
> +			opts->flags |= CGRP_ROOT_NOPREFIX;
>  			continue;
>  		}
>  		if (!strcmp(token, "clone_children")) {
> @@ -1210,7 +1210,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
>  			continue;
>  		}
>  		if (!strcmp(token, "xattr")) {
> -			set_bit(ROOT_XATTR, &opts->flags);
> +			opts->flags |= CGRP_ROOT_XATTR;
>  			continue;
>  		}
>  		if (!strncmp(token, "release_agent=", 14)) {
> @@ -1293,8 +1293,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
>  	 * with the old cpuset, so we allow noprefix only if mounting just
>  	 * the cpuset subsystem.
>  	 */
> -	if (test_bit(ROOT_NOPREFIX, &opts->flags) &&
> -	    (opts->subsys_mask & mask))
> +	if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
>  		return -EINVAL;
>  
>  
> @@ -2523,7 +2522,7 @@ static struct simple_xattrs *__d_xattrs(struct dentry *dentry)
>  static inline int xattr_enabled(struct dentry *dentry)
>  {
>  	struct cgroupfs_root *root = dentry->d_sb->s_fs_info;
> -	return test_bit(ROOT_XATTR, &root->flags);
> +	return root->flags & CGRP_ROOT_XATTR;
>  }
>  
>  static bool is_valid_xattr(const char *name)
> @@ -2695,7 +2694,7 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
>  
>  	simple_xattrs_init(&cft->xattrs);
>  
> -	if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
> +	if (subsys && !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) {
>  		strcpy(name, subsys->name);
>  		strcat(name, ".");
>  	}
> -- 
> 1.8.1.4
> 
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