linux-kernel - Re: [PATCH 01/16] hpsa: do readl after writel in main i/o path to ensure commands don't get lost.

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Message-ID: <4DC155E7.1010802@redhat.com>
Date:	Wed, 04 May 2011 15:34:31 +0200
From:	Tomas Henzl <thenzl@...hat.com>
To:	scameron@...rdog.cce.hp.com
CC:	james.bottomley@...senpartnership.com, linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org, smcameron@...oo.com,
	akpm@...ux-foundation.org, mikem@...rdog.cce.hp.com
Subject: Re: [PATCH 01/16] hpsa: do readl after writel in main i/o path to
 ensure	commands don't get lost.

On 05/04/2011 02:52 PM, scameron@...rdog.cce.hp.com wrote:
> On Wed, May 04, 2011 at 01:15:50PM +0200, Tomas Henzl wrote:
>   
>> On 05/03/2011 09:58 PM, Stephen M. Cameron wrote:
>>     
>>> From: Stephen M. Cameron <scameron@...rdog.cce.hp.com>
>>>
>>> Apparently we've been doin it rong for a decade, but only lately do we
>>> run into problems.
>>>
>>> Signed-off-by: Stephen M. Cameron <scameron@...rdog.cce.hp.com>
>>> ---
>>>  drivers/scsi/hpsa.h |    1 +
>>>  1 files changed, 1 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
>>> index 621a153..98c97ca 100644
>>> --- a/drivers/scsi/hpsa.h
>>> +++ b/drivers/scsi/hpsa.h
>>> @@ -212,6 +212,7 @@ static void SA5_submit_command(struct ctlr_info *h,
>>>  	dev_dbg(&h->pdev->dev, "Sending %x, tag = %x\n", c->busaddr,
>>>  		c->Header.Tag.lower);
>>>  	writel(c->busaddr, h->vaddr + SA5_REQUEST_PORT_OFFSET);
>>> +	(void) readl(h->vaddr + SA5_REQUEST_PORT_OFFSET);
>>>   
>>>       
>> Hi,
>> a small nit -
>> the (void) ^ is I think not needed for gcc and isn't present in the cciss.h patch
>>     
> I just put it there to make it clear that it ignoring the return of readl is 
> done intentionally, not accidentally.  If this goes against some coding convention,
> whatever, I'm not super attached to the (void), but I did put it there on purpose,
> and would have done it in cciss as well, had I thought of it at the time.
>   
I'm not sure what the coding convention says about this, I personally would omit it,
both ways are used in the kernel - so it is fine for me.

Ack - Tomas



> -- steve
>
>   
>> Tomas
>>
>>     
>>>  	h->commands_outstanding++;
>>>  	if (h->commands_outstanding > h->max_outstanding)
>>>  		h->max_outstanding = h->commands_outstanding;
>>>
>>> --
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>>>   
>>>       
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>   

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