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

[Jeff Garzik]

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




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