> -----Original Message----- > From: driverdev-devel-bounces@xxxxxxxxxxxxxxxxxxxxxx [mailto:driverdev- > devel-bounces@xxxxxxxxxxxxxxxxxxxxxx] On Behalf Of KY Srinivasan > Sent: Friday, June 20, 2014 2:37 PM > To: Jens Axboe; James Bottomley; michaelc@xxxxxxxxxxx > Cc: linux-scsi@xxxxxxxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; > jasowang@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; ohering@xxxxxxxx; > hch@xxxxxxxxxxxxx; apw@xxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx > Subject: RE: [PATCH 1/1] [SCSI] Fix a bug in deriving the FLUSH_TIMEOUT > from the basic I/O timeout > > > > > -----Original Message----- > > From: Jens Axboe [mailto:axboe@xxxxxxxxx] > > Sent: Friday, June 6, 2014 11:23 AM > > To: James Bottomley; michaelc@xxxxxxxxxxx > > Cc: linux-kernel@xxxxxxxxxxxxxxx; hch@xxxxxxxxxxxxx; > > devel@xxxxxxxxxxxxxxxxxxxxxx; apw@xxxxxxxxxxxxx; KY Srinivasan; linux- > > scsi@xxxxxxxxxxxxxxx; ohering@xxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; > > jasowang@xxxxxxxxxx > > Subject: Re: [PATCH 1/1] [SCSI] Fix a bug in deriving the > > FLUSH_TIMEOUT from the basic I/O timeout > > > > On 2014-06-06 11:52, James Bottomley wrote: > > > On Fri, 2014-06-06 at 12:18 -0500, Mike Christie wrote: > > >> On 6/5/14, 9:53 PM, KY Srinivasan wrote: > > >>> > > >>> > > >>>> -----Original Message----- > > >>>> From: Mike Christie [mailto:michaelc@xxxxxxxxxxx] > > >>>> Sent: Thursday, June 5, 2014 6:33 PM > > >>>> To: KY Srinivasan > > >>>> Cc: James Bottomley; linux-kernel@xxxxxxxxxxxxxxx; > > >>>> apw@xxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; > > hch@xxxxxxxxxxxxx; > > >>>> linux- scsi@xxxxxxxxxxxxxxx; ohering@xxxxxxxx; > > >>>> gregkh@xxxxxxxxxxxxxxxxxxx; jasowang@xxxxxxxxxx > > >>>> Subject: Re: [PATCH 1/1] [SCSI] Fix a bug in deriving the > > >>>> FLUSH_TIMEOUT from the basic I/O timeout > > >>>> > > >>>> On 06/04/2014 12:15 PM, KY Srinivasan wrote: > > >>>>> > > >>>>> > > >>>>>> -----Original Message----- > > >>>>>> From: James Bottomley [mailto:jbottomley@xxxxxxxxxxxxx] > > >>>>>> Sent: Wednesday, June 4, 2014 10:02 AM > > >>>>>> To: KY Srinivasan > > >>>>>> Cc: linux-kernel@xxxxxxxxxxxxxxx; apw@xxxxxxxxxxxxx; > > >>>>>> devel@xxxxxxxxxxxxxxxxxxxxxx; hch@xxxxxxxxxxxxx; linux- > > >>>>>> scsi@xxxxxxxxxxxxxxx; ohering@xxxxxxxx; > > >>>>>> gregkh@xxxxxxxxxxxxxxxxxxx; jasowang@xxxxxxxxxx > > >>>>>> Subject: Re: [PATCH 1/1] [SCSI] Fix a bug in deriving the > > >>>>>> FLUSH_TIMEOUT from the basic I/O timeout > > >>>>>> > > >>>>>> On Wed, 2014-06-04 at 09:33 -0700, K. Y. Srinivasan wrote: > > >>>>>>> Commit ID: 7e660100d85af860e7ad763202fff717adcdaacd added > > code > > >>>>>>> to derive the FLUSH_TIMEOUT from the basic I/O timeout. > > However, > > >>>>>>> this patch did not use the basic I/O timeout of the device. > > >>>>>>> Fix this > > bug. > > >>>>>>> > > >>>>>>> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > > >>>>>>> --- > > >>>>>>> drivers/scsi/sd.c | 4 +++- > > >>>>>>> 1 files changed, 3 insertions(+), 1 deletions(-) > > >>>>>>> > > >>>>>>> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index > > >>>>>>> e9689d5..54150b1 100644 > > >>>>>>> --- a/drivers/scsi/sd.c > > >>>>>>> +++ b/drivers/scsi/sd.c > > >>>>>>> @@ -832,7 +832,9 @@ static int > > sd_setup_write_same_cmnd(struct > > >>>>>>> scsi_device *sdp, struct request *rq) > > >>>>>>> > > >>>>>>> static int scsi_setup_flush_cmnd(struct scsi_device *sdp, > > >>>>>>> struct request *rq) { > > >>>>>>> - rq->timeout *= SD_FLUSH_TIMEOUT_MULTIPLIER; > > >>>>>>> + int timeout = sdp->request_queue->rq_timeout; > > >>>>>>> + > > >>>>>>> + rq->timeout = (timeout * > > SD_FLUSH_TIMEOUT_MULTIPLIER); > > >>>>>> > > >>>>>> Could you share where you found this to be a problem? It looks > > >>>>>> like a bug in block because all inbound requests being prepared > > >>>>>> should have a timeout set, so block would be the place to fix it. > > >>>>> > > >>>>> Perhaps; what I found was that the value in rq->timeout was 0 > > >>>>> coming into this function and thus multiplying obviously has no > effect. > > >>>>> > > >>>> > > >>>> I think you are right. We hit this problem because we are doing: > > >>>> > > >>>> scsi_request_fn -> blk_peek_request -> sd_prep_fn -> > > >>>> scsi_setup_flush_cmnd. > > >>>> > > >>>> At this time request->timeout is zero so the multiplication does > > >>>> nothing. See how sd_setup_write_same_cmnd will set the request- > > >timeout at this time. > > >>>> > > >>>> Then in scsi_request_fn we do: > > >>>> > > >>>> scsi_request_fn -> blk_start_request -> blk_add_timer. > > >>>> > > >>>> At this time it will set the request->timeout if something like > > >>>> req block pc users (like scsi_execute() or block/scsi_ioctl.c) or > > >>>> the write same code mentioned above have not set the timeout. > > >>> > > >>> I don't think this is a recent change. Prior to this commit, we > > >>> were setting the timeout value in this function; it just happened > > >>> to be a different constant unrelated to the I/O timeout. > > >>> > > >> > > >> Yeah, it looks like when 7e660100d85af860e7ad763202fff717adcdaacd > > >> was merged we were supposed to initialize it like in your patch in this > thread. > > >> > > >> I guess we could do your patch in this thread, or if we want the > > >> block layer to initialize the timeout before the prep_fn callout is > > >> called then we would need to have the blk-flush.c code to that when > > >> it sets up the request. If we do the latter, do we want the discard > > >> and write same code to initialize the request's timeout before the > > >> prep_fn callout is called too? > > > > > > I looked through the call chain; it seems to be intentional > > > behaviour on the part of block. Just from an mq point of view, it > > > would make better code if we unconditionally initialised rq->timeout > > > early and allowed prep to modify it and then dumped the > > > if(!req->timeout) in blk_add_timer(), but it's a marginal if > > > condition that would compile to a conditional store on sensible > > > architectures, so losing the conditional probably isn't worth worrying > about. > > > > > > Cc'd Jens for his opinion with the block patch > > > > I just committed this one earlier today: > > > > http://git.kernel.dk/?p=linux- > > block.git;a=commit;h=f6be4fb4bcb396fc3b1c134b7863351972de081f > > > > since I ran into the same thing on nvme. Either approach is fine with > > me, as they both allow override of the timeout before insertion. But > > we've always done the rq->timeout = 0 init, so I think we should just > > reinstate that behavior. > > James, > > How is this being fixed now. > > Regards, > > K. Y I still see this problem. There was talk of fixing it elsewhere. Regards, K. Y > > _______________________________________________ > devel mailing list > devel@xxxxxxxxxxxxxxxxxxxxxx > http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
