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Date: Tue, 6 Aug 2002 13:05:48 +0200
From: Jens Axboe <axboe@suse.de>
To: martin@dalecki.de
Cc: Petr Vandrovec <VANDROVE@vc.cvut.cz>, linux-kernel@vger.kernel.org,
       torvalds@transmeta.com
Subject: Re: [PATCH] 2.5.30 IDE 113
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On Tue, Aug 06 2002, Marcin Dalecki wrote:
> Uz.ytkownik Jens Axboe napisa?:
> >On Tue, Aug 06 2002, Marcin Dalecki wrote:
> >
> >>Uz.ytkownik Jens Axboe napisa?:
> >>
> >>>On Tue, Aug 06 2002, Marcin Dalecki wrote:
> >>>
> >>>
> >>>>device not per channel! If q->request_fn would properly return the
> >>>>error count instead of void, we could even get rid ot the
> >>>>checking for rq->errors after finishment... But well that's
> >>>>entierly different story.
> >>>
> >>>
> >>>That's nonsense! What exactly would you return from a request_fn after
> >>>having queued, eg, 20 commands? Error count is per request, anything
> >>>else would be stupid.
> >>
> >>Returning the error count in the case q->request_fn is called for
> >>a self submitted request like for example REQ_SPECIAL would be handy and 
> >>well defined. For the cumulative case it would of course make sense to 
> >>return the cumulative error count. Tough not very meaningfull, it would
> >>indicate the occurrence of the error very fine.
> >
> >
> >It's much nicer to maintain a sane API that doesn't depend on stuff like
> >the above. Cumulative error count, come on, you can't possibly be
> >serious?!
> 
> Hey don't get me wrong - I *do not* suggest adding it becouse I don't 
> think we are going to change the "eat as many as possible requests" 
> instead of "eat one request" semantics of the q->reuqest_fn().
> OK?

You look from the IDE perspective, I look from the interface
perspective. There's is no "eat one request" semantic of request_fn(),
in fact there's just the opposite. If you quit after having just
consumed one request, you must make sure to invoke request_fn _yourself_
later on -- or use the recent blk_start/stop_queue helpers.

-- 
Jens Axboe

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