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Message-ID: <20090730183014.GA6067@redhat.com>
Date: Thu, 30 Jul 2009 14:30:14 -0400
From: Vivek Goyal <vgoyal@...hat.com>
To: Jerome Marchand <jmarchan@...hat.com>
Cc: linux-kernel@...r.kernel.org,
containers@...ts.linux-foundation.org, dm-devel@...hat.com,
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paolo.valente@...more.it, fernando@....ntt.co.jp,
s-uchida@...jp.nec.com, taka@...inux.co.jp, jmoyer@...hat.com,
dhaval@...ux.vnet.ibm.com, m-ikeda@...jp.nec.com, agk@...hat.com,
akpm@...ux-foundation.org, peterz@...radead.org
Subject: Re: [PATCH 05/24] io-controller: Modify cfq to make use of flat
elevator fair queuing
On Thu, Jul 30, 2009 at 05:42:46PM +0200, Jerome Marchand wrote:
> Vivek Goyal wrote:
> > @@ -1616,11 +1234,12 @@ static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
> > struct cfq_data *cfqd = cic->key;
> > struct cfq_queue *cfqq;
> > unsigned long flags;
> > + struct request_queue *q = cfqd->queue;
>
> cfqd may be NULL here. We'd better test it before using it.
>
Thanks Jerome.
Actually I will drop this chage altogether. This is not required. I don't
know why did I change original code to introduce another local variable.
Thanks
Vivek
> >
> > if (unlikely(!cfqd))
> > return;
> >
> > - spin_lock_irqsave(cfqd->queue->queue_lock, flags);
> > + spin_lock_irqsave(q->queue_lock, flags);
> >
> > cfqq = cic->cfqq[BLK_RW_ASYNC];
> > if (cfqq) {
> > @@ -1637,7 +1256,7 @@ static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
> > if (cfqq)
> > cfq_mark_cfqq_prio_changed(cfqq);
> >
> > - spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
> > + spin_unlock_irqrestore(q->queue_lock, flags);
> > }
> >
> > static void cfq_ioc_set_ioprio(struct io_context *ioc)
>
>
> --- block/cfq-iosched.c.orig 2009-07-29 10:22:08.000000000 +0200
> +++ block/cfq-iosched.c 2009-07-30 17:25:05.000000000 +0200
> @@ -1271,11 +1271,12 @@ static void changed_ioprio(struct io_con
> struct cfq_data *cfqd = cic->key;
> struct cfq_queue *cfqq;
> unsigned long flags;
> - struct request_queue *q = cfqd->queue;
> + struct request_queue *q;
>
> if (unlikely(!cfqd))
> return;
>
> + q = cfqd->queue;
> spin_lock_irqsave(q->queue_lock, flags);
>
> cfqq = cic->cfqq[BLK_RW_ASYNC];
--
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