Re: [PATCH] Asynchronous scan support for libata

[Tejun Heo <htejun@gmail.com>]

Matthew Wilcox wrote:
> On Sat, Sep 08, 2007 at 05:10:27PM +0900, Tejun Heo wrote:
>> I think it's generally okay although it would need to spend quite some
>> time in -mm and we'll need to exclude several drivers which require
>> host-wide silence for mode programming (the current code is buggy but
>> sequential probing hides it pretty well) till host-wide exclusion is
>> implemented.
> 
> Can you tell me a bit more about these drivers?  Would it be possible to
> convert them to one host/many channels, which would give us the exclusion
> we want?

IIRC, sata_promise is of this type and there probably are a few old PATA
ones.  Ports on the host are mostly independent.  There's no need for
cross-port synchronization for most of the time but configuring transfer
mode requires host-wide quiescence.  Currently, the planned way to fix
the problem is to implement host-wide exclusion mechanism in the error
handler (summon EH of all other threads and wait till all of them are
parked) and it's on top of the TODO list, so I don't think it will take
too long.

Thanks.

-- 
tejun