Messages in this thread | | | Date | Wed, 12 Dec 2007 15:38:15 -0500 (EST) | Subject | Re: [PATCH 12/30] blk_end_request: changing ub (take 4) | From | Kiyoshi Ueda <> |
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Hi Pete,
On Tue, 11 Dec 2007 15:48:03 -0800, Pete Zaitcev <zaitcev@redhat.com> wrote: > > if (scsi_status == 0) { > > - uptodate = 1; > > + error = 0; > > } else { > > - uptodate = 0; > > + error = -EIO; > > rq->errors = scsi_status; > > } > > - 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(); > > Acked-by: Pete Zaitcev <zaitcev@redhat.com> > > I follow the discussion, actually, and wanted to ask someone to look > closer if it's appropriate to use __blk_end_request() here. > 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? If not, > and the above is sufficient, why have blk_end_request at all?
The difference between blk_end_request() and __blk_end_request() is whether the queue lock is held or not when end_that_request_last() is called. It's not relevant to the status of the request (error or not).
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.
Does that answer satisfy you?
Thanks, Kiyoshi Ueda
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