On Thu, 02 Mar 2017 10:36:17 -0800 James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > On March 2, 2017 10:23:24 AM PST, Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx> wrote: > >On Thu, 2 Mar 2017 14:25:14 +0100 > >Hannes Reinecke <hare@xxxxxxx> wrote: > > > >> On 03/02/2017 02:40 AM, Stephen Hemminger wrote: > >> > On Thu, 2 Mar 2017 01:56:15 +0100 > >> > Christoph Hellwig <hch@xxxxxx> wrote: > >> > > >> >> On Thu, Mar 02, 2017 at 01:01:35AM +0100, Christoph Hellwig wrote: > > > >> >>> On Wed, Mar 01, 2017 at 07:54:12AM -0800, Stephen Hemminger > >wrote: > >> >>>>> > > http://git.infradead.org/users/hch/block.git/commitdiff/148cff67b401e2229c076c0ea418712654be77e4 > > > >> >>>> > >> >>>> It appears that is already in the code I am testing in > >linux-next... > >> >>> > >> >>> It's in -next now, but it wasn't at the time you reported the > >bug. > >> >>> > >> >>> And it would sortof explain the bug if the INQUIRY data is > >correct > >> >>> in the scatterlist, but we ignore it, given that scsi_probe_lun > >> >>> ignores the result based on sense data. > >> >>> > >> >>> Can you check what happens with the horrible hack below: > >> >> > >> >> Strike that - we're checking result later, so this can't be the > >case. > >> >> > >> >> Now the other interesting thing is the memset in __scsi_exectute, > >> >> which looks very suspicious. Try the following please: > >> >> > >> >> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > >> >> index 3e32dc954c3c..22f4fb550561 100644 > >> >> --- a/drivers/scsi/scsi_lib.c > >> >> +++ b/drivers/scsi/scsi_lib.c > >> >> @@ -253,7 +253,8 @@ static int __scsi_execute(struct scsi_device > >*sdev, const unsigned char *cmd, > >> >> * and prevent security leaks by zeroing out the excess data. > >> >> */ > >> >> if (unlikely(rq->resid_len > 0 && rq->resid_len <= bufflen)) > >> >> - memset(buffer + (bufflen - rq->resid_len), 0, rq->resid_len); > >> >> +// memset(buffer + (bufflen - rq->resid_len), 0, rq->resid_len); > >> >> + printk_ratelimited("%s: got resid %d\n", __func__, > >rq->resid_len); > >> >> > >> >> if (resid) > >> >> *resid = rq->resid_len; > >> > > >> > > >> > Still fails but does print resid on some of the later INQUIRY > >commands (not the initial one). > >> > > >> Can you test what happens if you blank out the storvsc_drv > >workaround: > >> > >> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c > >> index 585e54f..c36f42d 100644 > >> --- a/drivers/scsi/storvsc_drv.c > >> +++ b/drivers/scsi/storvsc_drv.c > >> @@ -1060,13 +1060,13 @@ static void storvsc_on_io_completion(struct > >> storvsc_device *stor_device, > >> * We do this so we can distinguish truly fatal failues > >> * (srb status == 0x4) and off-line the device in that case. > >> */ > >> - > >> +#if 0 > >> if ((stor_pkt->vm_srb.cdb[0] == INQUIRY) || > >> (stor_pkt->vm_srb.cdb[0] == MODE_SENSE)) { > >> vstor_packet->vm_srb.scsi_status = 0; > >> vstor_packet->vm_srb.srb_status = > >SRB_STATUS_SUCCESS; > >> } > >> - > >> +#endif > >> > >> /* Copy over the status...etc */ > >> stor_pkt->vm_srb.scsi_status = > >vstor_packet->vm_srb.scsi_status; > >> > >> It might thappen that we're fail to interpret the 'Device not > >present' > >> status correctly (which will happen for non-connected DVDs) causing > >the > >> SCSI stack to make incorrect decisions later on. > >> > >> Cheers, > >> > >> Hannes > > > >There are several oddities about the host SCSI interface that I see: > > 1. The host bus seems to report up to 6 devices even though only 2 are > > present (Disk and CDROM). > >2. The CDROM emulation doesn't report the same status as a real device. > > 3. The host emulation of SCSI doesn't support all the page codes which > > is why there is the hack. > > > >But as James said, these don't appear to be related to the failure > >because > >the code worked before and only in post 4.11 merege is there a problem. > > Your wait for the hang trace is the most suggestive. It says we're waiting for a partition read to the spurious device. Previously this would have failed or timed out, so this seems to be the root cause. > > James > > Where is the number of valid LUN's determined during the scan process?
