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Re: [libvirt] [PATCHv7 3/4] libvirt/qemu - check address confliction before addition.



On Tue, 29 Mar 2011 13:30:03 +0800
Wen Congyang <wency cn fujitsu com> wrote:

> At 03/29/2011 01:13 PM, KAMEZAWA Hiroyuki Write:
> > On Tue, 29 Mar 2011 13:09:37 +0800
> > Wen Congyang <wency cn fujitsu com> wrote:
> > 
> >> At 03/25/2011 04:17 PM, KAMEZAWA Hiroyuki Write:
> >>> >From 638341bdf3eaac824e36d265e134608279750049 Mon Sep 17 00:00:00 2001
> >>> From: KAMEZAWA Hiroyuki <kamezawa hiroyu jp fujitsu com>
> >>> Date: Fri, 25 Mar 2011 17:10:58 +0900
> >>> Subject: [PATCHv7 3/4] libvirt/qemu - check address confliction before addition.
> >>>
> >>> qemuDomainAttachDevicePersistent() calls qemuDomainAssignPCIAddresses()
> >>> and virDomainDefAddImplicitControllers() at the end of its call.
> >>>
> >>> But PCI/Drive address confliction checks are
> >>>  PCI - confliction will be found but error report is not verbose.
> >>>  Drive - never done.
> >>>
> >>> For example, you can add following (unusual) 2 devices without errors.
> >>>
> >>> <disk type='file' device='disk'>
> >>>    <driver name='qemu' type='raw'/>
> >>>    <source file='/var/lib/libvirt/images/test3.img'/>
> >>>    <target dev="sdx" bus='scsi'/>
> >>>    <address type='drive' controller='0' bus='0' unit='0'/>
> >>> </disk>
> >>>
> >>> <disk type='file' device='disk'>
> >>>    <driver name='qemu' type='raw'/>
> >>>    <source file='/var/lib/libvirt/images/test3.img'/>
> >>>    <target dev="sdy" bus='scsi'/>
> >>>    <address type='drive' controller='0' bus='0' unit='0'/>
> >>> </disk>
> >>>
> >>> It's better to check drive address confliction before addition.
> >>>
> >>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa hiroyu jp fujitsu com>
> >>> ---
> >>>  src/conf/domain_conf.c   |   59 ++++++++++++++++++++++++++++++++++++++++++++++
> >>>  src/conf/domain_conf.h   |    2 +
> >>>  src/libvirt_private.syms |    1 +
> >>>  src/qemu/qemu_driver.c   |    9 +++++++
> >>>  4 files changed, 71 insertions(+), 0 deletions(-)
> >>>
> >>> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> >>> index 3e3f342..4a54f62 100644
> >>> --- a/src/conf/domain_conf.c
> >>> +++ b/src/conf/domain_conf.c
> >>> @@ -1287,6 +1287,65 @@ void virDomainDefClearDeviceAliases(virDomainDefPtr def)
> >>>      virDomainDeviceInfoIterate(def, virDomainDeviceInfoClearAlias, NULL);
> >>>  }
> >>>  
> >>> +static int virDomainDeviceAddressMatch(virDomainDefPtr def ATTRIBUTE_UNUSED,
> >>> +                                       virDomainDeviceInfoPtr info,
> >>> +                                       void *opaque)
> >>> +{
> >>> +    virDomainDeviceInfoPtr checked = opaque;
> >>> +    /* skip to check confliction of alias */
> >>> +    if (info->type != checked->type)
> >>> +            return 0;
> >>> +    if (info->alias && checked->alias && strcmp(info->alias, checked->alias))
> >>> +            return -1;
> >>> +    if (!memcmp(&info->addr, &checked->addr, sizeof(info->addr)))
> >>> +            return -1;
> >>> +    return 0;
> >>> +}
> >>> +
> >>> +int virDomainDefFindDeviceAddressConflict(virDomainDefPtr def,
> >>> +                                          virDomainDeviceDefPtr dev)
> >>> +{
> >>> +    virDomainDeviceInfoPtr checked;
> >>> +
> >>> +    switch (dev->type) {
> >>> +    case VIR_DOMAIN_DEVICE_DISK:
> >>> +        checked = &dev->data.disk->info;
> >>> +        break;
> >>> +    case VIR_DOMAIN_DEVICE_FS:
> >>> +        checked = &dev->data.fs->info;
> >>> +        break;
> >>> +    case VIR_DOMAIN_DEVICE_NET:
> >>> +        checked = &dev->data.net->info;
> >>> +        break;
> >>> +    case VIR_DOMAIN_DEVICE_INPUT:
> >>> +        checked = &dev->data.input->info;
> >>> +        break;
> >>> +    case VIR_DOMAIN_DEVICE_SOUND:
> >>> +        checked = &dev->data.sound->info;
> >>> +        break;
> >>> +    case VIR_DOMAIN_DEVICE_VIDEO:
> >>> +        checked = &dev->data.video->info;
> >>> +        break;
> >>> +    case VIR_DOMAIN_DEVICE_HOSTDEV:
> >>> +        checked = &dev->data.hostdev->info;
> >>> +        break;
> >>> +    case VIR_DOMAIN_DEVICE_WATCHDOG:
> >>> +        checked = &dev->data.watchdog->info;
> >>> +        break;
> >>> +    case VIR_DOMAIN_DEVICE_CONTROLLER:
> >>> +        checked = &dev->data.controller->info;
> >>> +        break;
> >>> +    case VIR_DOMAIN_DEVICE_GRAPHICS: /* has no address info */
> >>> +        return 0;
> >>> +    default:
> >>> +        virDomainReportError(VIR_ERR_INTERNAL_ERROR,
> >>> +                             "%s", _("Unknown device type"));
> >>> +        return -1;
> >>
> >> You report error here, but you report error in caller(qemuDomainAttachDevicePersistent())
> >> again.
> > 
> > "unknown device type" is an internal/"should never happen" error rathar than
> > errors reported in the caller.
> > 
> > I think this error should be reported. Internal error implies bug.
> 
> Yes, this should not happen. If it happens, the error message will be overwritten by the caller.
> We can report error here if virDomainDeviceInfoIterate() returns -1, and the caller do not
> report error.
> 

Is that make usability of this function ? If we report error, this function cannot
be used for simple sanity check of pci addresses.

Hmm, I'll replace this with DEBUG message. ok and never add error report here.
Ok ?

Thanks,
-Kame




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