[libvirt] [PATCH] qemu: Restore error/cleanup logic for qemuBuildNetCommandLine

[John Ferlan]

The virDomainConfVMNWFilterTeardown was called in the error path of
qemuBuildCommandLine once network setup was partially or fully completed
using the last_good_net as the basis to determine which filters needed
to be torn down.  Commit id 'ef2ab8fd' moved that inside the new
qemuBuildNetCommandLine, so that lost the failure.  Moving that cleanup
back outside the call to the more general failure case.

Signed-off-by: John Ferlan <jferlan at redhat.com>
---

Jan notes post push that the cleanup path after building the network
command line was there for any other failures and not just the failure
in building the network command line:

http://www.redhat.com/archives/libvir-list/2016-March/msg00561.html

Even though the teardown is called during qemuProcessStop from
virDomainConfVMNWFilterTeardown, the cleanup here could still be done.

The reason for moving it inside was based on a different patch where the
desire was to not leak anything that could have changed inside one of the
moved qemuBuild*CommandLine functions. In this case, though since it's
used more generally for cleanup, it seems a good idea to return it.

The other option would be to just let qemuProcessStop handle it and a
different patch to remove the error reset logic.

 src/qemu/qemu_command.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index ba8c216..2e15c05 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -7659,10 +7659,10 @@ qemuBuildNetCommandLine(virCommandPtr cmd,
                         bool emitBootindex,
                         size_t *nnicindexes,
                         int **nicindexes,
-                        int *bootHostdevNet)
+                        int *bootHostdevNet,
+                        int *last_good_net)
 {
     size_t i;
-    int last_good_net = -1;
 
     if (!def->nnets) {
         /* If we have -device, then we set -nodefault already */
@@ -7697,9 +7697,9 @@ qemuBuildNetCommandLine(virCommandPtr cmd,
                                               qemuCaps, vlan, bootNet, vmop,
                                               standalone, nnicindexes,
                                               nicindexes) < 0)
-                goto error;
+                return -1;
 
-            last_good_net = i;
+            *last_good_net = i;
             /* if this interface is a type='hostdev' interface and we
              * haven't yet added a "bootindex" parameter to an
              * emulated network device, save the bootindex - hostdev
@@ -7714,11 +7714,6 @@ qemuBuildNetCommandLine(virCommandPtr cmd,
         }
     }
     return 0;
-
- error:
-    for (i = 0; last_good_net != -1 && i <= last_good_net; i++)
-        virDomainConfNWFilterTeardown(def->nets[i]);
-    return -1;
 }
 
 
@@ -8604,6 +8599,7 @@ qemuBuildCommandLine(virConnectPtr conn,
     bool emitBootindex = false;
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
     int bootHostdevNet = 0;
+    int last_good_net = -1;
 
 
     VIR_DEBUG("conn=%p driver=%p def=%p mon=%p json=%d "
@@ -8725,7 +8721,7 @@ qemuBuildCommandLine(virConnectPtr conn,
 
     if (qemuBuildNetCommandLine(cmd, driver, def, qemuCaps, vmop, standalone,
                                 emitBootindex, nnicindexes, nicindexes,
-                                &bootHostdevNet) < 0)
+                                &bootHostdevNet, &last_good_net) < 0)
         goto error;
 
     if (qemuBuildSmartcardCommandLine(logManager, cmd, def, qemuCaps) < 0)
@@ -9280,6 +9276,8 @@ qemuBuildCommandLine(virConnectPtr conn,
     /* free up any resources in the network driver
      * but don't overwrite the original error */
     originalError = virSaveLastError();
+    for (i = 0; last_good_net != -1 && i <= last_good_net; i++)
+        virDomainConfNWFilterTeardown(def->nets[i]);
     virSetError(originalError);
     virFreeError(originalError);
     virCommandFree(cmd);
-- 
2.5.0