[libvirt] [PATCH v3] qemu: Add callback struct for qemuBuildCommandLine

[Daniel P. Berrange]

On Fri, May 17, 2013 at 06:17:07PM +0800, Osier Yang wrote:
> On 17/05/13 18:12, Daniel P. Berrange wrote:
> >On Thu, May 16, 2013 at 11:02:00PM +0800, Osier Yang wrote:
> >>Since 0d70656afded, it starts to access the sysfs files to build
> >>the qemu command line (by virSCSIDeviceGetSgName, which is to find
> >>out the scsi generic device name by adpater:bus:target:unit), there
> >>is no way to work around, qemu wants to see the scsi generic device
> >>like "/dev/sg6" anyway.
> >>
> >>And there might be other places which need to access sysfs files
> >>when building qemu command line in future.
> >>
> >>Instead of increasing the arguments of qemuBuildCommandLine, this
> >>introduces a new callback for qemuBuildCommandLine, and thus tests
> >>can register their own callbacks for sysfs test input files accessing.
> >>
> >>* src/qemu/qemu_command.h: (New callback struct
> >>                             qemuBuildCommandLineCallbacks;
> >>                             extern buildCommandLineCallbacks)
> >>* src/qemu/qemu_command.c: (wire up the callback struct)
> >>* src/qemu/qemu_driver.c: (Use the new syntax of qemuBuildCommandLine)
> >>* src/qemu/qemu_hotplug.c: Likewise
> >>* src/qemu/qemu_process.c: Likewise
> >>* tests/qemuxml2argvtest.c: (Helper testSCSIDeviceGetSgName;
> >>                              callback struct testCallbacks;
> >>                              Use the callback struct)
> >>* src/tests/qemuxmlnstest.c  Use the new syntax of qemuBuildCommandLine)
> >>---
> >>  src/qemu/qemu_command.c  | 28 ++++++++++++++++++++--------
> >>  src/qemu/qemu_command.h  | 16 ++++++++++++++--
> >>  src/qemu/qemu_driver.c   |  3 ++-
> >>  src/qemu/qemu_hotplug.c  |  6 ++++--
> >>  src/qemu/qemu_process.c  |  3 ++-
> >>  tests/qemuxml2argvtest.c | 21 ++++++++++++++++++++-
> >>  tests/qemuxmlnstest.c    |  3 ++-
> >>  7 files changed, 64 insertions(+), 16 deletions(-)
> >>
> >>diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> >>index 5b95c07..e775479 100644
> >>--- a/src/qemu/qemu_command.c
> >>+++ b/src/qemu/qemu_command.c
> >>@@ -4757,18 +4757,25 @@ qemuBuildUSBHostdevUsbDevStr(virDomainHostdevDefPtr dev)
> >>  char *
> >>  qemuBuildSCSIHostdevDrvStr(virDomainHostdevDefPtr dev,
> >>-                           virQEMUCapsPtr qemuCaps ATTRIBUTE_UNUSED)
> >>+                           virQEMUCapsPtr qemuCaps ATTRIBUTE_UNUSED,
> >>+                           qemuBuildCommandLineCallbacksPtr callbacks)
> >>  {
> >>      virBuffer buf = VIR_BUFFER_INITIALIZER;
> >>      char *sg = NULL;
> >>-    if (!(sg = virSCSIDeviceGetSgName(dev->source.subsys.u.scsi.adapter,
> >>-                                      dev->source.subsys.u.scsi.bus,
> >>-                                      dev->source.subsys.u.scsi.target,
> >>-                                      dev->source.subsys.u.scsi.unit))) {
> >>-        goto error;
> >>+    if (!callbacks) {
> >>+        virReportError(VIR_ERR_INVALID_ARG, "%s",
> >>+                       _("callbacks cannot be NULL"));
> >>+        return NULL;
> >I think I'd remove this check and....
> >
> >
> >>diff --git a/src/qemu/qemu_command.h b/src/qemu/qemu_command.h
> >>index 36dfa6b..23b6af3 100644
> >>--- a/src/qemu/qemu_command.h
> >>+++ b/src/qemu/qemu_command.h
> >>@@ -61,7 +71,8 @@ virCommandPtr qemuBuildCommandLine(virConnectPtr conn,
> >>                                     const char *migrateFrom,
> >>                                     int migrateFd,
> >>                                     virDomainSnapshotObjPtr current_snapshot,
> >>-                                   enum virNetDevVPortProfileOp vmop)
> >>+                                   enum virNetDevVPortProfileOp vmop,
> >>+                                   qemuBuildCommandLineCallbacksPtr callbacks)
> >>      ATTRIBUTE_NONNULL(1);
> >...add another ATTRIBUTE_NONNULL here and...
> 
> Do we need ATTRIBUT_NONULL for qemuBuildCommandLine too? the
> callbacks could be NULL in case of it won't call qemuBuildSCSIHostdevDrvStr,
> or something else in future.

Yes, we should expect to use this facility in other places too, so we
should add NUNULL here to prepare for that.

> If it should be NONNULL, I have to set up the callback from qemuxmlnstest.c
> too, the callbacks is meaningless for it though.

Yep, could put a reusable callback impl in testutilsqemu.c
so that we don't need to duplicate it in all the tests.

Daniel
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