[Devel] Re: [PATCH 2/4] cgroups: subsystem module loading interface

[Ben Blum]

On Mon, Dec 28, 2009 at 02:32:20PM +0800, Li Zefan wrote:
> > Add interface between cgroups subsystem management and module loading
> > 
> > From: Ben Blum <bblum at andrew.cmu.edu>
> > 
> > This patch implements rudimentary module-loading support for cgroups - namely,
> > a cgroup_load_subsys (similar to cgroup_init_subsys) for use as a module
> > initcall, and a struct module pointer in struct cgroup_subsys.
> > 
> > Several functions that might be wanted by modules have had EXPORT_SYMBOL added
> > to them, but it's unclear exactly which functions want it and which won't.
> > 
> > Signed-off-by: Ben Blum <bblum at andrew.cmu.edu>
> 
> Acked-by: Li Zefan <lizf at cn.fujitsu.com>
> 
> Some small nitpicks:
> 
> > --- a/kernel/cgroup.c
> > +++ b/kernel/cgroup.c
> > @@ -2477,6 +2477,7 @@ int cgroup_add_file(struct cgroup *cgrp,
> >  		error = PTR_ERR(dentry);
> >  	return error;
> >  }
> > +EXPORT_SYMBOL_GPL(cgroup_add_file);
> 
> I got compile errors, because you forgot to include <linux/module.h>
> 
> ...
> > +	write_lock(&css_set_lock);
> > +	for (i = 0; i < CSS_SET_TABLE_SIZE; i++) {
> > +		struct css_set *cg;
> > +		struct hlist_node *node, *tmp;
> > +		struct hlist_head *bucket = &css_set_table[i], *new_bucket;
> 
> Please add a blank line between variable declaration and other code.
> 
> And elsewhere in this patchset.
> 

checkpatch.pl didn't trip on this [and the more screenspace-intensive
comment style]; are they cgroups-specific style requirements or from
somewhere higher up?

> > +		hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) {
> > +			/* skip entries that we already rehashed */
> > +			if (cg->subsys[ss->subsys_id])
> > +				continue;
> > +			/* remove existing entry */
> > +			hlist_del(&cg->hlist);
> > +			/* set new value */
> > +			cg->subsys[ss->subsys_id] = css;
> > +			/* recompute hash and restore entry */
> > +			new_bucket = css_set_hash(cg->subsys);
> > +			hlist_add_head(&cg->hlist, new_bucket);
> > +		}
> > +	}
> > +	write_unlock(&css_set_lock);
> 
> 
> 
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