On Tue, Sep 08, 2020 at 05:53:16PM +0000, Felipe Franciosi wrote:
>
>
> > On Sep 8, 2020, at 3:22 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
> >
> > On 28/08/20 14:21, Matej Genci wrote:
> >> VirtIO 1.0 spec says
> >> The removed and rescan events ... when sent for LUN 0, they MAY
> >> apply to the entire target so the driver can ask the initiator
> >> to rescan the target to detect this.
> >>
> >> This change introduces the behaviour described above by scanning the
> >> entire scsi target when LUN is set to 0. This is both a functional and a
> >> performance fix. It aligns the driver with the spec and allows control
> >> planes to hotplug targets with large numbers of LUNs without having to
> >> request a RESCAN for each one of them.
> >>
> >> Signed-off-by: Matej Genci <matej@xxxxxxxxxxx>
> >> Suggested-by: Felipe Franciosi <felipe@xxxxxxxxxxx>
> >> ---
> >> drivers/scsi/virtio_scsi.c | 7 ++++++-
> >> 1 file changed, 6 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> >> index bfec84aacd90..a4b9bc7b4b4a 100644
> >> --- a/drivers/scsi/virtio_scsi.c
> >> +++ b/drivers/scsi/virtio_scsi.c
> >> @@ -284,7 +284,12 @@ static void virtscsi_handle_transport_reset(struct virtio_scsi *vscsi,
> >>
> >> switch (virtio32_to_cpu(vscsi->vdev, event->reason)) {
> >> case VIRTIO_SCSI_EVT_RESET_RESCAN:
> >> - scsi_add_device(shost, 0, target, lun);
> >> + if (lun == 0) {
> >> + scsi_scan_target(&shost->shost_gendev, 0, target,
> >> + SCAN_WILD_CARD, SCSI_SCAN_INITIAL);
> >> + } else {
> >> + scsi_add_device(shost, 0, target, lun);
> >> + }
> >> break;
> >> case VIRTIO_SCSI_EVT_RESET_REMOVED:
> >> sdev = scsi_device_lookup(shost, 0, target, lun);
> >>
> >
> >
> > Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>
> Cc: stable@xxxxxxxxxxxxxxx
>
> Thanks, Paolo.
>
> I'm Cc'ing stable as I believe this fixes a driver bug where it
> doesn't follow the spec. Per commit message, today devices are
> required to issue RESCAN events for each LUN behind a target when
> hotplugging, or risking the driver not seeing the new LUNs.
>
> Is this enough? Or should we resend after merge per below?
> https://www.kernel.org/doc/Documentation/process/stable-kernel-rules.rst
You need to let stable know the git commit id of the patch in Linus's
tree if the cc: stable is not on the final commit that gets merged.
thanks,
greg k-h
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