Hi Pete,
On Thu, 13 Dec 2007 13:59:16 -0800, Pete Zaitcev <[email protected]> wrote:
> > > > - end_that_request_first(rq, uptodate, rq->hard_nr_sectors);
> > > > - end_that_request_last(rq, uptodate);
> > > > + if (__blk_end_request(rq, error, blk_rq_bytes(rq)))
> > > > + BUG();
> > >
> > > My understanding was, blk_end_request() is the same thing, only
> > > takes the queue lock. But then, should I refactor ub so that it
> > > calls __blk_end_request if request function ends with an error
> > > and blk_end_request if the end-of-IO even is processed?
> >
> > I'm using __blk_end_request() here and I think it's sufficient, because:
> > o end_that_request_last() must be called with the queue lock held
> > o ub_end_rq() calls end_that_request_last() without taking
> > the queue lock in itself.
> > So the queue lock must have been taken outside ub_end_rq().
> >
> > But, if ub is calling end_that_request_last() without the queue lock,
> > it is a bug in the original code and we should use blk_end_request()
> > to fix that.
>
> So, I have to rewrite ub to split the paths after all, right?
> Let's do this then: I'll wait until your patch gets to Linus and
> then update it with the split. The reason is, I need the whole
> enchilada applied and I don't want to bother tracking iterations
> and all the little segments (of which you already have 30).
> Until then, ub will have a race by using your original small patch.
No.
Are you doubting that the current ub code has the problem, aren't you?
My patch shouldn't introduce a NEW problem to ub.
I have investigated all code paths which call ub_end_rq() in ub.c,
and confirmed that ub_end_rq() is always called with the queue lock
held. (sc->lock is registered as a queue lock.)
So there is no such race in the current ub code.
You don't need to rewrite ub.
Thanks,
Kiyoshi Ueda
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
