Re: [PATCH] Fix aic7xxx del_timer_sync() deadlock

[Jeff Garzik <jgarzik@pobox.com>]

Jens Axboe wrote:
> On Sat, Feb 28 2004, Jeff Garzik wrote:
> 
>>Jens Axboe wrote:
>>
>>>The only nasty right now is that you cannot unconditionally call
>>>blk_stop_queue(), it requires a manual blk_start_queue() on io
>>>completion which will only happen if io is pending of course. I just got
>>>an idea on how to do that properly, I'll make sure it works in any case.
>>
>>hmmm...  I thought the model was to call blk_stop_queue() when you can 
>>accept no more requests, and call blk_start_queue() once you can start 
>>accepting more requests.
>>
>>That would imply that blk_start_queue() is OK when there is no more I/O 
>>pending...
> 
> 
> That is the model. The problem is that you don't have an opportunitty to
> call blk_start_queue() if there's no more IO pending (you typicall do it
> from io completion). There's no problem with doing that.

Help me out here, I must be dumb :)

If you call blk_start_queue() from io completion -- as you should -- 
then it gets called unconditionally, regardless of whether there is IO 
pending or not.  The LLD should only care if it can accept more 
requests.  The opportunity seems to be there, to me...

	Jeff