linux-kernel - Re: [PATCH 02/10] Common flat fair queuing code in elevaotor layer

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Date:	Wed, 1 Apr 2009 21:06:40 -0700
From:	Divyesh Shah <dpshah@...gle.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	nauman@...gle.com, lizf@...fujitsu.com, mikew@...gle.com,
	fchecconi@...il.com, paolo.valente@...more.it,
	jens.axboe@...cle.com, ryov@...inux.co.jp,
	fernando@...ellilink.co.jp, s-uchida@...jp.nec.com,
	taka@...inux.co.jp, guijianfeng@...fujitsu.com,
	arozansk@...hat.com, jmoyer@...hat.com, oz-kernel@...hat.com,
	dhaval@...ux.vnet.ibm.com, balbir@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org,
	containers@...ts.linux-foundation.org, akpm@...ux-foundation.org,
	menage@...gle.com, peterz@...radead.org
Subject: Re: [PATCH 02/10] Common flat fair queuing code in elevaotor layer

On Wed, Mar 11, 2009 at 6:56 PM, Vivek Goyal <vgoyal@...hat.com> wrote:
> +/*
> + * elv_exit_fq_data is called before we call elevator_exit_fn. Before
> + * we ask elevator to cleanup its queues, we do the cleanup here so
> + * that all the group and idle tree references to ioq are dropped. Later
> + * during elevator cleanup, ioc reference will be dropped which will lead
> + * to removal of ioscheduler queue as well as associated ioq object.
> + */
> +void elv_exit_fq_data(struct elevator_queue *e)
> +{
> +       struct elv_fq_data *efqd = &e->efqd;
> +       struct request_queue *q = efqd->queue;
> +
> +       if (!elv_iosched_fair_queuing_enabled(e))
> +               return;
> +
> +       elv_shutdown_timer_wq(e);
> +
> +       spin_lock_irq(q->queue_lock);
> +       /* This should drop all the idle tree references of ioq */
> +       elv_free_idle_ioq_list(e);
> +       spin_unlock_irq(q->queue_lock);
> +
> +       elv_shutdown_timer_wq(e);
> +
> +       BUG_ON(timer_pending(&efqd->idle_slice_timer));
> +       io_free_root_group(e);
> +}
>

Hi Vivek,
        When cleaning up the elv_fq_data and ioqs for the iogs
associated with a device on elv_exit(), I don't see any iogs except
the root group being freed. In io_disconnect_groups() you remove the
ioqs from each of the iog and move them to the root iog and then
delete the root iog. Am I missing something here or are there leftover
iogs at elv_exit?

-Divyesh
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