[PATCH 08/10] scsi/scsi_bus: Add scsi_device_get

[Paolo Bonzini]

From: Maxim Levitsky <mlevitsk@redhat.com>

Add scsi_device_get which finds the scsi device
and takes a reference to it.

Suggested-by: Stefan Hajnoczi <stefanha@gmail.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200913160259.32145-8-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
        Compared to Maxim's patch, I am avoiding the extra argument
        to do_scsi_device_find by moving the RCU_READ_LOCK_GUARD()
        out of do_scsi_device_find itself.

 hw/scsi/scsi-bus.c     | 11 +++++++++++
 include/hw/scsi/scsi.h |  1 +
 2 files changed, 12 insertions(+)

diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index 7599113efe..eda8cb7e70 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -73,6 +73,17 @@ SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int 
id, int lun)
     return do_scsi_device_find(bus, channel, id, lun, false);
 }
 
+SCSIDevice *scsi_device_get(SCSIBus *bus, int channel, int id, int lun)
+{
+    SCSIDevice *d;
+    RCU_READ_LOCK_GUARD();
+    d = do_scsi_device_find(bus, channel, id, lun, false);
+    if (d) {
+        object_ref(d);
+    }
+    return d;
+}
+
 static void scsi_device_realize(SCSIDevice *s, Error **errp)
 {
     SCSIDeviceClass *sc = SCSI_DEVICE_GET_CLASS(s);
diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h
index 7a55cdbd74..09fa5c9d2a 100644
--- a/include/hw/scsi/scsi.h
+++ b/include/hw/scsi/scsi.h
@@ -190,6 +190,7 @@ int scsi_device_get_sense(SCSIDevice *dev, uint8_t *buf, 
int len, bool fixed);
 int scsi_SG_IO_FROM_DEV(BlockBackend *blk, uint8_t *cmd, uint8_t cmd_size,
                         uint8_t *buf, uint8_t buf_size);
 SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int target, int lun);
+SCSIDevice *scsi_device_get(SCSIBus *bus, int channel, int target, int lun);
 
 /* scsi-generic.c. */
 extern const SCSIReqOps scsi_generic_req_ops;
-- 
2.26.2