Re: [PATCH][noop-iosched] don't reuse a freed request
From: Jens Axboe
Date: Mon Oct 31 2005 - 04:10:37 EST
On Mon, Oct 31 2005, Tejun Heo wrote:
> >For now, we should add the former.
> Yeap, also verified oops doesn't happen with the following patch.
> I'll soon post a patch to convert noop such that it does proper
> dispatching. BTW, while I was looking at the code, I found something
> else, in elv_former/latter_request functions, if the iosched doesn't
> supply the callbacks, it uses rq->queue_list.prev/next implicitly
> (without this, this noop bug wouldn't have been triggered). I think
> this code is not necessary anymore. What do you think?
Well that should still work for noop, if it has its own internal
queueing list. But I would be quite fine with removing that implicit
next/prev support and simply require io scheds to supply these functions
always if they require rq-to-rq merging. Noop is the only one that
relied on this in the past, now seems a good time to clean that up as
Besides, as you note, with merging disallowed on the ->queue_head, they
don't work as expected anymore.
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