Re: [PATCH] block: optimizations in blk_rq_timed_out_timer()

[malahal@us.ibm.com]

Jens Axboe [jens.axboe@oracle.com] wrote:
> > Yes, we should not access it although I don't think the request can be
> > freed while the existing code is accessing the deadline field. What 
> > likely can happen is that we may call mod_timer with jiffies that is
> > older than current which would call the timer immediately...
> 
> That would not call the timer immediately, that will not call it until
> jiffies reaches that value again. So you're looking at a minimum of 49
> days :-)

I remember the timer code treating "past" expiry times as special. If
not, then we have a real bug! It is also hard to guarantee in
blk_rq_timed_out_timer() that we always call mod_timer with future
expiry time!

--Malahal.