[PATCH] qemu_driver.c: Coverity fix in qemuNodeDeviceDetachFlags()

[Daniel Henrique Barboza]

Commit 76f47889326c4 made qemuNodeDeviceDetachFlags() unusable due to an
'if then else if' chain that will always results in a 'return -1',
regardless of 'driverName' input. This slipped through review process
and Gitlab CI, making it clear now that there is no unit tests
exercising this code ATM.

LUckily John Ferlan caught this up with his Coverity scan and spared us
from an unneeded headache later on.

Fixes: 76f47889326c45d2732711bc6dd5751aaf6e5194
Reported-by: John Ferlan <jferlan at redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413 at gmail.com>
---
 src/qemu/qemu_driver.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index f1035a536e..b9bbdf8d48 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -11998,7 +11998,6 @@ qemuNodeDeviceDetachFlags(virNodeDevicePtr dev,
                           unsigned int flags)
 {
     virQEMUDriverPtr driver = dev->conn->privateData;
-    bool vfio = qemuHostdevHostSupportsPassthroughVFIO();
     virHostdevManagerPtr hostdev_mgr = driver->hostdevMgr;
 
     virCheckFlags(0, -1);
@@ -12006,22 +12005,27 @@ qemuNodeDeviceDetachFlags(virNodeDevicePtr dev,
     if (!driverName)
         driverName = "vfio";
 
-    if (STREQ(driverName, "vfio") && !vfio) {
-        virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
-                       _("VFIO device assignment is currently not "
-                         "supported on this system"));
-         return -1;
-    } else if (STREQ(driverName, "kvm")) {
+    /* Only the 'vfio' driver is supported and a special error message for
+     * the previously supported 'kvm' driver is provided below. */
+    if (STRNEQ(driverName, "vfio") && STRNEQ(driverName, "kvm")) {
+        virReportError(VIR_ERR_INVALID_ARG,
+                       _("unknown driver name '%s'"), driverName);
+        return -1;
+    }
+
+    if (STREQ(driverName, "kvm")) {
         virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
                        _("KVM device assignment is no longer "
                          "supported on this system"));
         return -1;
-    } else {
-        virReportError(VIR_ERR_INVALID_ARG,
-                       _("unknown driver name '%s'"), driverName);
-        return -1;
     }
 
+    if (!qemuHostdevHostSupportsPassthroughVFIO()) {
+        virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
+                       _("VFIO device assignment is currently not "
+                         "supported on this system"));
+         return -1;
+    }
 
     /* virNodeDeviceDetachFlagsEnsureACL() is being called by
      * virDomainDriverNodeDeviceDetachFlags() */
-- 
2.29.2