* Re: [PATCH] Rescan the entire target on transport reset when LUN is 0 [not found] ` <200ad446-1242-9555-96b6-4fa94ee27ec7@redhat.com> @ 2020-09-08 17:53 ` Felipe Franciosi 2020-09-09 5:54 ` Greg KH 0 siblings, 1 reply; 2+ messages in thread From: Felipe Franciosi @ 2020-09-08 17:53 UTC (permalink / raw) To: Paolo Bonzini, stable@vger.kernel.org Cc: Matej Genci, linux-kernel@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, stefanha@redhat.com, jejb@linux.ibm.com, martin.petersen@oracle.com, virtualization@lists.linux-foundation.org, linux-scsi@vger.kernel.org > On Sep 8, 2020, at 3:22 PM, Paolo Bonzini <pbonzini@redhat.com> 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@nutanix.com> >> Suggested-by: Felipe Franciosi <felipe@nutanix.com> >> --- >> 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@redhat.com> Cc: stable@vger.kernel.org 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 F. ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] Rescan the entire target on transport reset when LUN is 0 2020-09-08 17:53 ` [PATCH] Rescan the entire target on transport reset when LUN is 0 Felipe Franciosi @ 2020-09-09 5:54 ` Greg KH 0 siblings, 0 replies; 2+ messages in thread From: Greg KH @ 2020-09-09 5:54 UTC (permalink / raw) To: Felipe Franciosi Cc: Paolo Bonzini, stable@vger.kernel.org, Matej Genci, linux-kernel@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, stefanha@redhat.com, jejb@linux.ibm.com, martin.petersen@oracle.com, virtualization@lists.linux-foundation.org, linux-scsi@vger.kernel.org On Tue, Sep 08, 2020 at 05:53:16PM +0000, Felipe Franciosi wrote: > > > > On Sep 8, 2020, at 3:22 PM, Paolo Bonzini <pbonzini@redhat.com> 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@nutanix.com> > >> Suggested-by: Felipe Franciosi <felipe@nutanix.com> > >> --- > >> 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@redhat.com> > > Cc: stable@vger.kernel.org > > 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 ^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-09-08 17:53 ` [PATCH] Rescan the entire target on transport reset when LUN is 0 Felipe Franciosi
2020-09-09 5:54 ` Greg KH
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