From: Vivek Goyal <vgoyal@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: axboe@kernel.dk, ctalbott@google.com, rni@google.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 10/13] block, cfq: unlink cfq_io_context's immediately
Date: Wed, 26 Oct 2011 15:48:57 -0400 [thread overview]
Message-ID: <20111026194857.GF355@redhat.com> (raw)
In-Reply-To: <1319593719-19132-11-git-send-email-tj@kernel.org>
On Tue, Oct 25, 2011 at 06:48:36PM -0700, Tejun Heo wrote:
[..]
> +/*
> + * Slow path for ioc release in put_io_context(). Performs double-lock
> + * dancing to unlink all cic's and then frees ioc.
> + */
> +static void ioc_release_fn(struct work_struct *work)
> {
> - if (!hlist_empty(&ioc->cic_list)) {
> - struct cfq_io_context *cic;
> + struct io_context *ioc = container_of(work, struct io_context,
> + release_work);
> + struct request_queue *last_q = NULL;
> +
> + spin_lock_irq(&ioc->lock);
> +
> + while (!hlist_empty(&ioc->cic_list)) {
> + struct cfq_io_context *cic = hlist_entry(ioc->cic_list.first,
> + struct cfq_io_context,
> + cic_list);
> + if (cic->q != last_q) {
> + struct request_queue *this_q = cic->q;
> +
> + /*
> + * Need to switch to @this_q. Once we release
> + * @ioc->lock, it can go away along with @cic.
> + * Hold on to it.
> + */
> + __blk_get_queue(this_q);
> +
> + /*
> + * blk_put_queue() might sleep thanks to kobject
> + * idiocy. Always release both locks, put and
> + * restart.
> + */
> + if (last_q) {
> + spin_unlock(last_q->queue_lock);
> + spin_unlock_irq(&ioc->lock);
> + blk_put_queue(last_q);
> + } else {
> + spin_unlock_irq(&ioc->lock);
> + }
> +
> + last_q = this_q;
> + spin_lock_irq(this_q->queue_lock);
> + spin_lock(&ioc->lock);
> + continue;
> + }
> + ioc_release_depth_inc(cic->q);
> + cic->exit(cic);
> + cic->release(cic);
> + ioc_release_depth_dec(cic->q);
cic->release(cic) can free the cic? Are we accessing cic after freeing it
up in ioc_release_depth_dec(cic->q);
Thanks
Vivek
next prev parent reply other threads:[~2011-10-26 19:49 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-26 1:48 [PATCHSET block:for-3.2/core] rescue cfq from RCU death sprial :) Tejun Heo
2011-10-26 1:48 ` [PATCH 01/13] ida: make ida_simple_get/put() IRQ safe Tejun Heo
2011-10-26 4:42 ` Rusty Russell
2011-10-26 20:28 ` Tejun Heo
2011-10-26 1:48 ` [PATCH 02/13] block, cfq: move cfqd->cic_index to q->id Tejun Heo
2011-10-26 1:48 ` [PATCH 03/13] block: misc ioc cleanups Tejun Heo
2011-10-26 1:48 ` [PATCH 04/13] block: make ioc get/put interface more conventional and fix race on alloction Tejun Heo
2011-10-26 16:01 ` Vivek Goyal
2011-10-26 19:29 ` Tejun Heo
2011-10-26 21:30 ` [PATCH UPDATED " Tejun Heo
2011-10-26 1:48 ` [PATCH 05/13] block: misc updates to blk_get_queue() Tejun Heo
2011-10-26 1:48 ` [PATCH 06/13] block, cfq: misc updates to cfq_io_context Tejun Heo
2011-10-27 15:39 ` Vivek Goyal
2011-10-27 16:24 ` Tejun Heo
2011-10-26 1:48 ` [PATCH 07/13] block, cfq: move ioc ioprio/cgroup changed handling to cic Tejun Heo
2011-10-26 1:48 ` [PATCH 08/13] block, cfq: fix race condition in cic creation path and tighten locking Tejun Heo
2011-10-26 1:48 ` [PATCH 09/13] block, cfq: fix cic lookup locking Tejun Heo
2011-10-26 1:48 ` [PATCH 10/13] block, cfq: unlink cfq_io_context's immediately Tejun Heo
2011-10-26 19:48 ` Vivek Goyal [this message]
2011-10-26 19:55 ` Tejun Heo
2011-10-26 20:38 ` Vivek Goyal
2011-10-26 20:54 ` Tejun Heo
2011-10-26 21:31 ` [PATCH UPDATED " Tejun Heo
2011-10-27 14:31 ` Vivek Goyal
2011-10-27 16:17 ` Tejun Heo
2011-10-27 17:05 ` Vivek Goyal
2011-10-27 17:11 ` Tejun Heo
2011-10-26 1:48 ` [PATCH 11/13] block, cfq: remove delayed unlink Tejun Heo
2011-10-26 1:48 ` [PATCH 12/13] block, cfq: kill ioc_gone Tejun Heo
2011-10-26 1:48 ` [PATCH 13/13] block, cfq: kill cic->key Tejun Heo
2011-10-26 21:36 ` [PATCHSET block:for-3.2/core] rescue cfq from RCU death sprial :) Tejun Heo
2011-10-27 15:32 ` Vivek Goyal
2011-10-27 16:10 ` Tejun Heo
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