On 06/04/2014 12:15 PM, KY Srinivasan wrote: > > >> -----Original Message----- >> From: James Bottomley [mailto:jbottom...@parallels.com] >> Sent: Wednesday, June 4, 2014 10:02 AM >> To: KY Srinivasan >> Cc: linux-ker...@vger.kernel.org; a...@canonical.com; >> de...@linuxdriverproject.org; h...@infradead.org; linux- >> s...@vger.kernel.org; oher...@suse.com; gre...@linuxfoundation.org; >> jasow...@redhat.com >> 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 <k...@microsoft.com> >>> --- >>> 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. _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
