Re: 2.6.4-rc-bk3: hdparm -X locks up IDE

[Jeff Garzik <jgarzik@pobox.com>]

Bartlomiej Zolnierkiewicz wrote:
> On Thursday 11 of March 2004 15:48, Jens Axboe wrote:
> 
>>On Thu, Mar 11 2004, Bartlomiej Zolnierkiewicz wrote:
>>
>>>On Thursday 11 of March 2004 15:14, Denis Vlasenko wrote:
>>>
>>>>I discovered that hdparm -X <mode> /dev/hda can lock up IDE
>>>>interface if there is some activity.
>>>
>>>Known bug and is on TODO but fixing it ain't easy.
>>>Thanks for a report anyway.
>>
>>Wouldn't it be possible to do the stuff that needs serializing from the
>>end_request() part and get automatic synchronization with normal
>>requests?
> 
> 
> That's the way to do it (REQ_SPECIAL) but unfortunately on some chipsets
> we need to synchronize both channels (whereas we don't need to serialize
> normal operations).

blk_stop_queue() on all queues attached to the hardware?

You need to synchronize anyway for the rare hardware that reports itself 
as "simplex" -- one DMA engine for both channels.

	Jeff