File virtio-scsi-use-scsi_device_get.patch of Package qemu.20153

From: Maxim Levitsky <mlevitsk@redhat.com>
Date: Tue, 6 Oct 2020 15:39:03 +0300
Subject: virtio-scsi: use scsi_device_get

Git-commit: 07a47d4a1879370009baab44f1f387610d88a299
References: bsc#1184574

This will help us to avoid the scsi device disappearing
after we took a reference to it.

It doesn't by itself forbid case when we try to access
an unrealized device

Suggested-by: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200913160259.32145-9-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20201006123904.610658-13-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Lin Ma <lma@suse.com>
---
 hw/scsi/virtio-scsi.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 52c3a964ecb112a9d1c00bfbe57d..57789f40d040096d163f2a9986da 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -34,7 +34,7 @@ static inline int virtio_scsi_get_lun(uint8_t *lun)
     return ((lun[2] << 8) | lun[3]) & 0x3FFF;
 }
 
-static inline SCSIDevice *virtio_scsi_device_find(VirtIOSCSI *s, uint8_t *lun)
+static inline SCSIDevice *virtio_scsi_device_get(VirtIOSCSI *s, uint8_t *lun)
 {
     if (lun[0] != 1) {
         return NULL;
@@ -42,7 +42,7 @@ static inline SCSIDevice *virtio_scsi_device_find(VirtIOSCSI *s, uint8_t *lun)
     if (lun[2] != 0 && !(lun[2] >= 0x40 && lun[2] < 0x80)) {
         return NULL;
     }
-    return scsi_device_find(&s->bus, 0, lun[1], virtio_scsi_get_lun(lun));
+    return scsi_device_get(&s->bus, 0, lun[1], virtio_scsi_get_lun(lun));
 }
 
 void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req)
@@ -261,7 +261,7 @@ static inline void virtio_scsi_ctx_check(VirtIOSCSI *s, SCSIDevice *d)
  *  case of async cancellation. */
 static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
 {
-    SCSIDevice *d = virtio_scsi_device_find(s, req->req.tmf.lun);
+    SCSIDevice *d = virtio_scsi_device_get(s, req->req.tmf.lun);
     SCSIRequest *r, *next;
     BusChild *kid;
     int target;
@@ -377,10 +377,10 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
 
         rcu_read_lock();
         QTAILQ_FOREACH_RCU(kid, &s->bus.qbus.children, sibling) {
-             d = SCSI_DEVICE(kid->child);
-             if (d->channel == 0 && d->id == target) {
-                qdev_reset_all(&d->qdev);
-             }
+            SCSIDevice *d1 = SCSI_DEVICE(kid->child);
+            if (d1->channel == 0 && d1->id == target) {
+                qdev_reset_all(&d1->qdev);
+            }
         }
         rcu_read_unlock();
 
@@ -393,14 +393,17 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
         break;
     }
 
+    object_unref(OBJECT(d));
     return ret;
 
 incorrect_lun:
     req->resp.tmf.response = VIRTIO_SCSI_S_INCORRECT_LUN;
+    object_unref(OBJECT(d));
     return ret;
 
 fail:
     req->resp.tmf.response = VIRTIO_SCSI_S_BAD_TARGET;
+    object_unref(OBJECT(d));
     return ret;
 }
 
@@ -618,7 +621,7 @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
     trace_virtio_scsi_cmd_req(virtio_scsi_get_lun(req->req.cmd.lun),
                               req->req.cmd.tag, req->req.cmd.cdb[0]);
 
-    d = virtio_scsi_device_find(s, req->req.cmd.lun);
+    d = virtio_scsi_device_get(s, req->req.cmd.lun);
     if (!d) {
         req->resp.cmd.response = VIRTIO_SCSI_S_BAD_TARGET;
         virtio_scsi_complete_cmd_req(req);
@@ -634,10 +637,12 @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
             req->sreq->cmd.xfer > req->qsgl.size)) {
         req->resp.cmd.response = VIRTIO_SCSI_S_OVERRUN;
         virtio_scsi_complete_cmd_req(req);
+        object_unref(OBJECT(d));
         return -ENOBUFS;
     }
     scsi_req_ref(req->sreq);
     blk_io_plug(d->conf.blk);
+    object_unref(OBJECT(d));
     return 0;
 }