Re: [PATCH v5 9/9] devcg: propagate local changes down thehierarchy

[Serge E. Hallyn]

Quoting Aristeu Rozanski (aris@xxxxxxxxxx):
> +/**
> + * propagate_exception - propagates a new exception to the children
> + * @devcg_root: device cgroup that added a new exception
> + *
> + * returns: 0 in case of success, != 0 in case of error
> + */
> +static int propagate_exception(struct dev_cgroup *devcg_root)
> +{
> +	struct cgroup *root = devcg_root->css.cgroup;
> +	struct dev_cgroup *devcg, *parent, *tmp;
> +	int rc = 0;
> +	LIST_HEAD(pending);
> +
> +	get_online_devcg(root, &pending);
> +
> +	list_for_each_entry_safe(devcg, tmp, &pending, propagate_pending) {
> +		parent = cgroup_to_devcgroup(devcg->css.cgroup->parent);
> +
> +		dev_exception_clean(&devcg->exceptions);
> +		if (devcg->behavior == parent->behavior) {
> +			rc = dev_exceptions_copy(&devcg->exceptions, &parent->exceptions);

Let's say parent A and child B both have DEFAULT_DENY, with a set of let's
say 5 whitelist exceptions.  Now the parent adds two more whitelist
exceptions.  As you say, we don't propagate those.

Now the parent removes one of it's whitelist exceptions.
devcgroup_update_access() calls dev_exception_rm() followed by
propagate_exception(), which comes here and copies the parent's
whitelist - including the two new whitelist rules - to the
child.

-serge
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/