[PATCH v3 6/7] scsi: Add scsi_device_get

[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>
---
 hw/scsi/scsi-bus.c     | 31 ++++++++++++++++++++++++-------
 include/hw/scsi/scsi.h |  2 ++
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index 92d412b65c..677074eaa6 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -1572,8 +1572,13 @@ static char *scsibus_get_fw_dev_path(DeviceState *dev)
     return g_strdup_printf("channel@%x/%s@%x,%x", d->channel,
                            qdev_fw_name(dev), d->id, d->lun);
 }
-
-SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun)
+/*
+ * Finds a matching channel/id/lun device on scsi bus, and
+ * takes a reference to it and returns it.
+ * If we don't find exact match (channel/bus/lun),
+ * we will return the first device which matches channel/bus
+ */
+SCSIDevice *scsi_device_get(SCSIBus *bus, int channel, int id, int lun)
 {
     BusChild *kid;
     SCSIDevice *target_dev = NULL;
@@ -1586,25 +1591,37 @@ SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun)
 
         if (dev->channel == channel && dev->id == id) {
             if (dev->lun == lun) {
+                object_ref(OBJECT(dev));
                 rcu_read_unlock();
                 return dev;
             }
 
-            /*
-             * If we don't find exact match (channel/bus/lun),
-             * we will return the first device which matches channel/bus
-             */
-
             if (!target_dev) {
                 target_dev = dev;
             }
         }
     }
 
+    object_ref(OBJECT(target_dev));
     rcu_read_unlock();
     return target_dev;
 }
 
+/*
+ * This function works like scsi_device_get but doesn't take a reference
+ * to the returned object.
+ * Devices that run under the QEMU global mutex can use this function.
+ * Devices that run outside the QEMU global mutex must use
+ * scsi_device_get() instead.
+ */
+SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun)
+{
+    SCSIDevice *dev = scsi_device_get(bus, channel, id, lun);
+
+    object_unref(OBJECT(dev));
+    return dev;
+}
+
 /* SCSI request list.  For simplicity, pv points to the whole device */
 
 static int put_scsi_requests(QEMUFile *f, void *pv, size_t size,
diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h
index 2fc23e44ba..6e11ece641 100644
--- a/include/hw/scsi/scsi.h
+++ b/include/hw/scsi/scsi.h
@@ -193,7 +193,9 @@ void scsi_generic_read_device_inquiry(SCSIDevice *dev);
 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