[libvirt] handling qemuMonitorAddDevice failure: missing drive_del function?

[Jim Meyering]

Daniel P. Berrange wrote:

> On Tue, May 18, 2010 at 03:23:23PM +0200, Jim Meyering wrote:
>> In src/qemu/qemu_driver.c, coverity gripes (rightly) about this:
>>
>>  6912    qemuDomainObjEnterMonitorWithDriver(driver, vm);
>>  6913    if (qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE) {
>>  6914        ret = qemuMonitorAddDrive(priv->mon, drivestr);
>>  6915        if (ret == 0)
>> No check of the return value of "qemuMonitorAddDevice(priv->mon, devstr)".
>> Calling function "qemuMonitorAddDevice" without checking return value.
>>  6916            qemuMonitorAddDevice(priv->mon, devstr);
>>  6917            /* XXX remove the drive upon fail */
>>  6918    } else {
>>
>> Does anyone have a preference on how to deal with it
>> while we wait for a drive-removal function?
>> I think it deserves at least a diagnostic.
>
> Add a VIR_WARN message i guess

Here you go:


>From 62ece506ead7534ac37a70a6750a97e69809d088 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering at redhat.com>
Date: Tue, 18 May 2010 16:02:12 +0200
Subject: [PATCH] do not ignore qemuMonitorAddDrive failure; make uses identical

There were three very similar uses of qemuMonitorAddDrive.
This change makes the three 17-line sequences identical.
* src/qemu/qemu_driver.c (qemudDomainAttachPciDiskDevice): Detect
failure.  Add VIR_WARN and braces.
(qemudDomainAttachSCSIDisk): Add VIR_WARN and braces.
(qemudDomainAttachUsbMassstorageDevice): Likewise.
---
 src/qemu/qemu_driver.c |   44 +++++++++++++++++++++++++++++---------------
 1 files changed, 29 insertions(+), 15 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 5649a20..9d23191 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -6912,15 +6912,21 @@ static int qemudDomainAttachPciDiskDevice(struct qemud_driver *driver,
         goto error;
     }

     qemuDomainObjEnterMonitorWithDriver(driver, vm);
     if (qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE) {
         ret = qemuMonitorAddDrive(priv->mon, drivestr);
-        if (ret == 0)
-            qemuMonitorAddDevice(priv->mon, devstr);
-            /* XXX remove the drive upon fail */
+        if (ret == 0) {
+            ret = qemuMonitorAddDevice(priv->mon, devstr);
+            if (ret < 0) {
+                VIR_WARN(_("qemuMonitorAddDevice failed on %s (%s)"),
+                         drivestr, devstr);
+                /* XXX should call 'drive_del' on error but this does not
+                   exist yet */
+            }
+        }
     } else {
         virDomainDevicePCIAddress guestAddr;
         ret = qemuMonitorAddPCIDisk(priv->mon,
                                     disk->src,
                                     type,
                                     &guestAddr);
@@ -7126,18 +7132,22 @@ static int qemudDomainAttachSCSIDisk(struct qemud_driver *driver,
         virReportOOMError();
         goto error;
     }

     qemuDomainObjEnterMonitorWithDriver(driver, vm);
     if (qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE) {
-        ret = qemuMonitorAddDrive(priv->mon,
-                                  drivestr);
-        if (ret == 0)
-            ret = qemuMonitorAddDevice(priv->mon,
-                                       devstr);
-            /* XXX should call 'drive_del' on error but this does not exist yet */
+        ret = qemuMonitorAddDrive(priv->mon, drivestr);
+        if (ret == 0) {
+            ret = qemuMonitorAddDevice(priv->mon, devstr);
+            if (ret < 0) {
+                VIR_WARN(_("qemuMonitorAddDevice failed on %s (%s)"),
+                         drivestr, devstr);
+                /* XXX should call 'drive_del' on error but this does not
+                   exist yet */
+            }
+        }
     } else {
         virDomainDeviceDriveAddress driveAddr;
         ret = qemuMonitorAttachDrive(priv->mon,
                                      drivestr,
                                      &cont->info.addr.pci,
                                      &driveAddr);
@@ -7215,18 +7225,22 @@ static int qemudDomainAttachUsbMassstorageDevice(struct qemud_driver *driver,
         virReportOOMError();
         goto error;
     }

     qemuDomainObjEnterMonitorWithDriver(driver, vm);
     if (qemuCmdFlags & QEMUD_CMD_FLAG_DEVICE) {
-        ret = qemuMonitorAddDrive(priv->mon,
-                                  drivestr);
-        if (ret == 0)
-            ret = qemuMonitorAddDevice(priv->mon,
-                                       devstr);
-            /* XXX should call 'drive_del' on error but this does not exist yet */
+        ret = qemuMonitorAddDrive(priv->mon, drivestr);
+        if (ret == 0) {
+            ret = qemuMonitorAddDevice(priv->mon, devstr);
+            if (ret < 0) {
+                VIR_WARN(_("qemuMonitorAddDevice failed on %s (%s)"),
+                         drivestr, devstr);
+                /* XXX should call 'drive_del' on error but this does not
+                   exist yet */
+            }
+        }
     } else {
         ret = qemuMonitorAddUSBDisk(priv->mon, disk->src);
     }
     qemuDomainObjExitMonitorWithDriver(driver, vm);

     if (ret < 0)
--
1.7.1.250.g7d1e8