[Qemu-devel] [PATCH 1/2] qdev: qdev_unplug(): Use error_set()

[Luiz Capitulino]

It currently uses qerror_report(), but next commits will convert
the drive_del command to the QAPI and this requires using
error_set().

One particularity of qerror_report() is that it knows when it's
running on monitor context or command-line context and prints the
error message accordingly. error_set() doesn't do this, so we
have to be careful not to drop error messages.

qdev_unplug() has three kinds of usages:

 1. It's called when hot adding a device fails, to undo anything
    that has been done before hitting the error

 2. It's called by function monitor functions like device_del(),
    to unplug a device

 3. It's used by xen_platform.c in a way that doesn't _seem_ to
    be in monitor context

Only item 2 can print an error message to the user, this commit
maintains that.

Signed-off-by: Luiz Capitulino <address@hidden>
---
 hw/pci-hotplug.c     |   15 ++++++++++++---
 hw/qdev-monitor.c    |   11 ++++++++++-
 hw/qdev.c            |    5 +++--
 hw/qdev.h            |    3 ++-
 hw/usb/dev-storage.c |    2 +-
 hw/xen_platform.c    |    4 ++--
 6 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/hw/pci-hotplug.c b/hw/pci-hotplug.c
index 5c6307f..a060917 100644
--- a/hw/pci-hotplug.c
+++ b/hw/pci-hotplug.c
@@ -32,6 +32,7 @@
 #include "virtio-blk.h"
 #include "qemu-config.h"
 #include "blockdev.h"
+#include "error.h"
 
 #if defined(TARGET_I386)
 static PCIDevice *qemu_pci_hot_add_nic(Monitor *mon,
@@ -191,7 +192,7 @@ static PCIDevice *qemu_pci_hot_add_storage(Monitor *mon,
             dev = NULL;
         if (dev && dinfo) {
             if (scsi_hot_add(mon, &dev->qdev, dinfo, 0) != 0) {
-                qdev_unplug(&dev->qdev);
+                qdev_unplug(&dev->qdev, NULL);
                 dev = NULL;
             }
         }
@@ -256,8 +257,9 @@ void pci_device_hot_add(Monitor *mon, const QDict *qdict)
 static int pci_device_hot_remove(Monitor *mon, const char *pci_addr)
 {
     PCIDevice *d;
-    int dom, bus;
+    int dom, bus, ret;
     unsigned slot;
+    Error *errp = NULL;
 
     if (pci_read_devaddr(mon, pci_addr, &dom, &bus, &slot)) {
         return -1;
@@ -268,7 +270,14 @@ static int pci_device_hot_remove(Monitor *mon, const char 
*pci_addr)
         monitor_printf(mon, "slot %d empty\n", slot);
         return -1;
     }
-    return qdev_unplug(&d->qdev);
+
+    ret = qdev_unplug(&d->qdev, &errp);
+    if (error_is_set(&errp)) {
+        monitor_printf(mon, "%s\n", error_get_pretty(errp));
+        error_free(errp);
+    }
+
+    return ret;
 }
 
 void do_pci_device_hot_remove(Monitor *mon, const QDict *qdict)
diff --git a/hw/qdev-monitor.c b/hw/qdev-monitor.c
index a310cc7..58fa943 100644
--- a/hw/qdev-monitor.c
+++ b/hw/qdev-monitor.c
@@ -578,13 +578,22 @@ int do_device_del(Monitor *mon, const QDict *qdict, 
QObject **ret_data)
 {
     const char *id = qdict_get_str(qdict, "id");
     DeviceState *dev;
+    Error *local_err = NULL;
+    int ret;
 
     dev = qdev_find_recursive(sysbus_get_default(), id);
     if (NULL == dev) {
         qerror_report(QERR_DEVICE_NOT_FOUND, id);
         return -1;
     }
-    return qdev_unplug(dev);
+
+    ret = qdev_unplug(dev, &local_err);
+    if (error_is_set(&local_err)) {
+        qerror_report_err(local_err);
+        error_free(local_err);
+    }
+
+    return ret;
 }
 
 void qdev_machine_init(void)
diff --git a/hw/qdev.c b/hw/qdev.c
index ee21d90..cf2a9a9 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -28,6 +28,7 @@
 #include "net.h"
 #include "qdev.h"
 #include "sysemu.h"
+#include "error.h"
 
 int qdev_hotplug = 0;
 static bool qdev_hot_added = false;
@@ -172,12 +173,12 @@ void qdev_set_legacy_instance_id(DeviceState *dev, int 
alias_id,
     dev->alias_required_for_version = required_for_version;
 }
 
-int qdev_unplug(DeviceState *dev)
+int qdev_unplug(DeviceState *dev, Error **errp)
 {
     DeviceClass *dc = DEVICE_GET_CLASS(dev);
 
     if (!dev->parent_bus->allow_hotplug) {
-        qerror_report(QERR_BUS_NO_HOTPLUG, dev->parent_bus->name);
+        error_set(errp, QERR_BUS_NO_HOTPLUG, dev->parent_bus->name);
         return -1;
     }
     assert(dc->unplug != NULL);
diff --git a/hw/qdev.h b/hw/qdev.h
index 9cc3f98..22cf490 100644
--- a/hw/qdev.h
+++ b/hw/qdev.h
@@ -7,6 +7,7 @@
 #include "qemu-option.h"
 #include "qapi/qapi-visit-core.h"
 #include "qemu/object.h"
+#include "error.h"
 
 typedef struct Property Property;
 
@@ -148,7 +149,7 @@ int qdev_init(DeviceState *dev) QEMU_WARN_UNUSED_RESULT;
 void qdev_init_nofail(DeviceState *dev);
 void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
                                  int required_for_version);
-int qdev_unplug(DeviceState *dev);
+int qdev_unplug(DeviceState *dev, Error **errp);
 void qdev_free(DeviceState *dev);
 int qdev_simple_unplug_cb(DeviceState *dev);
 void qdev_machine_creation_done(void);
diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
index bdbe7bd..d865a5e 100644
--- a/hw/usb/dev-storage.c
+++ b/hw/usb/dev-storage.c
@@ -499,7 +499,7 @@ static void usb_msd_password_cb(void *opaque, int err)
         err = usb_device_attach(&s->dev);
 
     if (err)
-        qdev_unplug(&s->dev.qdev);
+        qdev_unplug(&s->dev.qdev, NULL);
 }
 
 static const struct SCSIBusInfo usb_msd_scsi_info = {
diff --git a/hw/xen_platform.c b/hw/xen_platform.c
index 5a7c4cc..a9c52a6 100644
--- a/hw/xen_platform.c
+++ b/hw/xen_platform.c
@@ -87,7 +87,7 @@ static void unplug_nic(PCIBus *b, PCIDevice *d)
 {
     if (pci_get_word(d->config + PCI_CLASS_DEVICE) ==
             PCI_CLASS_NETWORK_ETHERNET) {
-        qdev_unplug(&(d->qdev));
+        qdev_unplug(&(d->qdev), NULL);
     }
 }
 
@@ -100,7 +100,7 @@ static void unplug_disks(PCIBus *b, PCIDevice *d)
 {
     if (pci_get_word(d->config + PCI_CLASS_DEVICE) ==
             PCI_CLASS_STORAGE_IDE) {
-        qdev_unplug(&(d->qdev));
+        qdev_unplug(&(d->qdev), NULL);
     }
 }
 
-- 
1.7.9.2.384.g4a92a