linux-kernel - Re: [PATCH 11/12] libata: use IRQ expecting

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Date:	Fri, 25 Jun 2010 09:44:16 +0200
From:	Tejun Heo <tj@...nel.org>
To:	Jeff Garzik <jeff@...zik.org>
CC:	mingo@...e.hu, tglx@...utronix.de, bphilips@...e.de,
	yinghai@...nel.org, akpm@...ux-foundation.org,
	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-ide@...r.kernel.org, stern@...land.harvard.edu,
	gregkh@...e.de, khali@...ux-fr.org
Subject: Re: [PATCH 11/12] libata: use IRQ expecting

Hello, Jeff.

On 06/25/2010 02:22 AM, Jeff Garzik wrote:
>> @@ -4972,6 +4972,8 @@ void ata_qc_complete(struct ata_queued_cmd *qc)
>>   {
>>       struct ata_port *ap = qc->ap;
>>
>> +    unexpect_irq(ap->irq_expect, false);
>> +
>>       /* XXX: New EH and old EH use different mechanisms to
>>        * synchronize EH with regular execution path.
>>        *
> 
> Unconditional use of unexpect_irq() here seems incorrect for some cases,
> such as sata_mv's use, where ata_qc_complete() is called multiple times
> rather than a singleton ata_qc_complete_multiple() call.

Indeed, sata_mv is calling ata_qc_complete() directly multiple times.
I still think calling unexpect_irq() from ata_qc_complete() is correct
as ata_qc_complete() is always a good indicator of completion events.
What's missing is a way for sata_mv to indicate that it has more
events to expect for, which under the current implementation only
sata_mv interrupt handler can determine.  I'll see if I can convert it
to use ata_qc_complete_multiple() instead.

Thanks.

-- 
tejun
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