[PATCH] Revert "virtio-scsi: Send "REPORTED LUNS CHANGED" sense data upon disk hotplug events"

[Stefano Garzarella <sgarzare@redhat.com>]

This reverts commit 8cc5583abe6419e7faaebc9fbd109f34f4c850f2.

That commit causes several problems in Linux as described in the BZ.
In particular, after a while, other devices on the bus are no longer
usable even if those devices are not affected by the hotunplug.
This may be a problem in Linux, but we have not been able to identify
it so far. So better to revert this patch until we find a solution.

Also, Oracle, which initially proposed this patch for a problem with
Solaris, seems to have already reversed it downstream:
    https://linux.oracle.com/errata/ELSA-2023-12065.html

Suggested-by: Thomas Huth <thuth@redhat.com>
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2176702
Cc: qemu-stable@nongnu.org
Cc: Mark Kanda <mark.kanda@oracle.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
 include/hw/scsi/scsi.h |  1 -
 hw/scsi/scsi-bus.c     | 18 ------------------
 hw/scsi/virtio-scsi.c  |  2 --
 3 files changed, 21 deletions(-)

diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h
index e2bb1a2fbf..7c8adf10b1 100644
--- a/include/hw/scsi/scsi.h
+++ b/include/hw/scsi/scsi.h
@@ -198,7 +198,6 @@ SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk,
                                       BlockdevOnError rerror,
                                       BlockdevOnError werror,
                                       const char *serial, Error **errp);
-void scsi_bus_set_ua(SCSIBus *bus, SCSISense sense);
 void scsi_bus_legacy_handle_cmdline(SCSIBus *bus);
 
 SCSIRequest *scsi_req_alloc(const SCSIReqOps *reqops, SCSIDevice *d,
diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index f80f4cb4fc..42a915f8b7 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -1617,24 +1617,6 @@ static int scsi_ua_precedence(SCSISense sense)
     return (sense.asc << 8) | sense.ascq;
 }
 
-void scsi_bus_set_ua(SCSIBus *bus, SCSISense sense)
-{
-    int prec1, prec2;
-    if (sense.key != UNIT_ATTENTION) {
-        return;
-    }
-
-    /*
-     * Override a pre-existing unit attention condition, except for a more
-     * important reset condition.
-     */
-    prec1 = scsi_ua_precedence(bus->unit_attention);
-    prec2 = scsi_ua_precedence(sense);
-    if (prec2 < prec1) {
-        bus->unit_attention = sense;
-    }
-}
-
 void scsi_device_set_ua(SCSIDevice *sdev, SCSISense sense)
 {
     int prec1, prec2;
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 45b95ea070..1f56607100 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -1080,7 +1080,6 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
 
         virtio_scsi_acquire(s);
         virtio_scsi_push_event(s, &info);
-        scsi_bus_set_ua(&s->bus, SENSE_CODE(REPORTED_LUNS_CHANGED));
         virtio_scsi_release(s);
     }
 }
@@ -1112,7 +1111,6 @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev,
     if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
         virtio_scsi_acquire(s);
         virtio_scsi_push_event(s, &info);
-        scsi_bus_set_ua(&s->bus, SENSE_CODE(REPORTED_LUNS_CHANGED));
         virtio_scsi_release(s);
     }
 }
-- 
2.41.0