scsi: Replace scsi_bus_new() with scsi_bus_init(), scsi_bus_init_named()

The function scsi_bus_new() creates a new SCSI bus; callers can
either pass in a name argument to specify the name of the new bus, or
they can pass in NULL to allow the bus to be given an automatically
generated unique name.  Almost all callers want to use the
autogenerated name; the only exception is the virtio-scsi device.

Taking a name argument that should almost always be NULL is an
easy-to-misuse API design -- it encourages callers to think perhaps
they should pass in some standard name like "scsi" or "scsi-bus".  We
don't do this anywhere for SCSI, but we do (incorrectly) do it for
other bus types such as i2c.

The function name also implies that it will return a newly allocated
object, when it in fact does in-place allocation.  We more commonly
name such functions foo_init(), with foo_new() being the
allocate-and-return variant.

Replace all the scsi_bus_new() callsites with either:
 * scsi_bus_init() for the usual case where the caller wants
   an autogenerated bus name
 * scsi_bus_init_named() for the rare case where the caller
   needs to specify the bus name

and document that for the _named() version it's then the caller's
responsibility to think about uniqueness of bus names.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20210923121153.23754-2-peter.maydell@linaro.org

hw/scsi/esp-pci.c

@@ -388,7 +388,7 @@ static void esp_pci_scsi_realize(PCIDevice *dev, Error **errp)
     pci_register_bar(dev, 0, PCI_BASE_ADDRESS_SPACE_IO, &pci->io);
     s->irq = pci_allocate_irq(dev);
 
-    scsi_bus_new(&s->bus, sizeof(s->bus), d, &esp_pci_scsi_info, NULL);
+    scsi_bus_init(&s->bus, sizeof(s->bus), d, &esp_pci_scsi_info);
 }
 
 static void esp_pci_scsi_exit(PCIDevice *d)

hw/scsi/esp.c

@@ -1348,7 +1348,7 @@ static void sysbus_esp_realize(DeviceState *dev, Error **errp)
 
     qdev_init_gpio_in(dev, sysbus_esp_gpio_demux, 2);
 
-    scsi_bus_new(&s->bus, sizeof(s->bus), dev, &esp_scsi_info, NULL);
+    scsi_bus_init(&s->bus, sizeof(s->bus), dev, &esp_scsi_info);
 }
 
 static void sysbus_esp_hard_reset(DeviceState *dev)

hw/scsi/lsi53c895a.c

@@ -2309,7 +2309,7 @@ static void lsi_scsi_realize(PCIDevice *dev, Error **errp)
     pci_register_bar(dev, 2, PCI_BASE_ADDRESS_SPACE_MEMORY, &s->ram_io);
     QTAILQ_INIT(&s->queue);
 
-    scsi_bus_new(&s->bus, sizeof(s->bus), d, &lsi_scsi_info, NULL);
+    scsi_bus_init(&s->bus, sizeof(s->bus), d, &lsi_scsi_info);
 }
 
 static void lsi_scsi_exit(PCIDevice *dev)

hw/scsi/megasas.c

@@ -2416,8 +2416,7 @@ static void megasas_scsi_realize(PCIDevice *dev, Error **errp)
         s->frames[i].state = s;
     }
 
-    scsi_bus_new(&s->bus, sizeof(s->bus), DEVICE(dev),
-                 &megasas_scsi_info, NULL);
+    scsi_bus_init(&s->bus, sizeof(s->bus), DEVICE(dev), &megasas_scsi_info);
 }
 
 static Property megasas_properties_gen1[] = {

hw/scsi/mptsas.c

@@ -1315,7 +1315,7 @@ static void mptsas_scsi_realize(PCIDevice *dev, Error **errp)
 
     s->request_bh = qemu_bh_new(mptsas_fetch_requests, s);
 
-    scsi_bus_new(&s->bus, sizeof(s->bus), &dev->qdev, &mptsas_scsi_info, NULL);
+    scsi_bus_init(&s->bus, sizeof(s->bus), &dev->qdev, &mptsas_scsi_info);
 }
 
 static void mptsas_scsi_uninit(PCIDevice *dev)

hw/scsi/scsi-bus.c

@@ -134,8 +134,8 @@ void scsi_device_unit_attention_reported(SCSIDevice *s)
 }
 
 /* Create a scsi bus, and attach devices to it.  */
-void scsi_bus_new(SCSIBus *bus, size_t bus_size, DeviceState *host,
-                  const SCSIBusInfo *info, const char *bus_name)
+void scsi_bus_init_named(SCSIBus *bus, size_t bus_size, DeviceState *host,
+                         const SCSIBusInfo *info, const char *bus_name)
 {
     qbus_create_inplace(bus, bus_size, TYPE_SCSI_BUS, host, bus_name);
     bus->busnr = next_scsi_bus++;

hw/scsi/spapr_vscsi.c

@@ -1216,8 +1216,7 @@ static void spapr_vscsi_realize(SpaprVioDevice *dev, Error **errp)
 
     dev->crq.SendFunc = vscsi_do_crq;
 
-    scsi_bus_new(&s->bus, sizeof(s->bus), DEVICE(dev),
-                 &vscsi_scsi_info, NULL);
+    scsi_bus_init(&s->bus, sizeof(s->bus), DEVICE(dev), &vscsi_scsi_info);
 
     /* ibmvscsi SCSI bus does not allow hotplug. */
     qbus_set_hotplug_handler(BUS(&s->bus), NULL);

hw/scsi/virtio-scsi.c

@@ -1019,8 +1019,8 @@ static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    scsi_bus_new(&s->bus, sizeof(s->bus), dev,
-                 &virtio_scsi_scsi_info, vdev->bus_name);
+    scsi_bus_init_named(&s->bus, sizeof(s->bus), dev,
+                       &virtio_scsi_scsi_info, vdev->bus_name);
     /* override default SCSI bus hotplug-handler, with virtio-scsi's one */
     qbus_set_hotplug_handler(BUS(&s->bus), OBJECT(dev));
 

hw/scsi/vmw_pvscsi.c

@@ -1180,8 +1180,7 @@ pvscsi_realizefn(PCIDevice *pci_dev, Error **errp)
 
     s->completion_worker = qemu_bh_new(pvscsi_process_completion_queue, s);
 
-    scsi_bus_new(&s->bus, sizeof(s->bus), DEVICE(pci_dev),
-                 &pvscsi_scsi_info, NULL);
+    scsi_bus_init(&s->bus, sizeof(s->bus), DEVICE(pci_dev), &pvscsi_scsi_info);
     /* override default SCSI bus hotplug-handler, with pvscsi's one */
     qbus_set_hotplug_handler(BUS(&s->bus), OBJECT(s));
     pvscsi_reset_state(s);

hw/usb/dev-storage-bot.c

@@ -37,8 +37,7 @@ static void usb_msd_bot_realize(USBDevice *dev, Error **errp)
         s->dev.auto_attach = 0;
     }
 
-    scsi_bus_new(&s->bus, sizeof(s->bus), DEVICE(dev),
-                 &usb_msd_scsi_info_bot, NULL);
+    scsi_bus_init(&s->bus, sizeof(s->bus), DEVICE(dev), &usb_msd_scsi_info_bot);
     usb_msd_handle_reset(dev);
 }
 

hw/usb/dev-storage-classic.c

@@ -65,8 +65,8 @@ static void usb_msd_storage_realize(USBDevice *dev, Error **errp)
     usb_desc_create_serial(dev);
     usb_desc_init(dev);
     dev->flags |= (1 << USB_DEV_FLAG_IS_SCSI_STORAGE);
-    scsi_bus_new(&s->bus, sizeof(s->bus), DEVICE(dev),
-                 &usb_msd_scsi_info_storage, NULL);
+    scsi_bus_init(&s->bus, sizeof(s->bus), DEVICE(dev),
+                 &usb_msd_scsi_info_storage);
     scsi_dev = scsi_bus_legacy_add_drive(&s->bus, blk, 0, !!s->removable,
                                          s->conf.bootindex, s->conf.share_rw,
                                          s->conf.rerror, s->conf.werror,

hw/usb/dev-uas.c

@@ -938,8 +938,7 @@ static void usb_uas_realize(USBDevice *dev, Error **errp)
     uas->status_bh = qemu_bh_new(usb_uas_send_status_bh, uas);
 
     dev->flags |= (1 << USB_DEV_FLAG_IS_SCSI_STORAGE);
-    scsi_bus_new(&uas->bus, sizeof(uas->bus), DEVICE(dev),
-                 &usb_uas_scsi_info, NULL);
+    scsi_bus_init(&uas->bus, sizeof(uas->bus), DEVICE(dev), &usb_uas_scsi_info);
 }
 
 static const VMStateDescription vmstate_usb_uas = {

include/hw/scsi/scsi.h

@@ -146,8 +146,34 @@ struct SCSIBus {
     const SCSIBusInfo *info;
 };
 
-void scsi_bus_new(SCSIBus *bus, size_t bus_size, DeviceState *host,
-                  const SCSIBusInfo *info, const char *bus_name);
+/**
+ * scsi_bus_init_named: Initialize a SCSI bus with the specified name
+ * @bus: SCSIBus object to initialize
+ * @bus_size: size of @bus object
+ * @host: Device which owns the bus (generally the SCSI controller)
+ * @info: structure defining callbacks etc for the controller
+ * @bus_name: Name to use for this bus
+ *
+ * This in-place initializes @bus as a new SCSI bus with a name
+ * provided by the caller. It is the caller's responsibility to make
+ * sure that name does not clash with the name of any other bus in the
+ * system. Unless you need the new bus to have a specific name, you
+ * should use scsi_bus_new() instead.
+ */
+void scsi_bus_init_named(SCSIBus *bus, size_t bus_size, DeviceState *host,
+                         const SCSIBusInfo *info, const char *bus_name);
+
+/**
+ * scsi_bus_init: Initialize a SCSI bus
+ *
+ * This in-place-initializes @bus as a new SCSI bus and gives it
+ * an automatically generated unique name.
+ */
+static inline void scsi_bus_init(SCSIBus *bus, size_t bus_size,
+                                 DeviceState *host, const SCSIBusInfo *info)
+{
+    scsi_bus_init_named(bus, bus_size, host, info, NULL);
+}
 
 static inline SCSIBus *scsi_bus_from_device(SCSIDevice *d)
 {