[dm-devel] Re: [PATCH 05/18] io-controller: Common hierarchical fair queuing code in elevaotor layer

[Gui Jianfeng]

Vivek Goyal wrote:
> This patch enables hierarchical fair queuing in common layer. It is
> controlled by config option CONFIG_GROUP_IOSCHED.
...
> +}
> +
> +void iocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
> +{
> +	struct io_cgroup *iocg = cgroup_to_io_cgroup(cgroup);
> +	struct hlist_node *n, *tmp;
> +	struct io_group *iog;
> +
> +	/*
> +	 * Since we are destroying the cgroup, there are no more tasks
> +	 * referencing it, and all the RCU grace periods that may have
> +	 * referenced it are ended (as the destruction of the parent
> +	 * cgroup is RCU-safe); bgrp->group_data will not be accessed by
> +	 * anything else and we don't need any synchronization.
> +	 */
> +	hlist_for_each_entry_safe(iog, n, tmp, &iocg->group_data, group_node)
> +		io_destroy_group(iocg, iog);
> +
> +	BUG_ON(!hlist_empty(&iocg->group_data));
> +

    Hi Vivek,

    IMHO, free_css_id() needs to be called here.

> +	kfree(iocg);
> +}
> +
> +void io_disconnect_groups(struct elevator_queue *e)
> +{
> +	struct hlist_node *pos, *n;
> +	struct io_group *iog;
> +	struct elv_fq_data *efqd = &e->efqd;
> +
> +	hlist_for_each_entry_safe(iog, pos, n, &efqd->group_list,
> +					elv_data_node) {
> +		hlist_del(&iog->elv_data_node);
> +

-- 
Regards
Gui Jianfeng