Re: [libvirt] [PATCH 3/4] qemu: Remove unnecessary virtio disk detach info.alias check
On 10/20/2017 08:21 AM, Ján Tomko wrote:
On Fri, Oct 20, 2017 at 08:03:29AM -0400, John Ferlan wrote:
> Since qemuAssignDeviceDiskAlias checks whether the input info.alias
> is already present, no need to check here as well.
>
> Signed-off-by: John Ferlan <jferlan(a)redhat.com>
> ---
> src/qemu/qemu_hotplug.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> index 51a7a68f84..9fbb3a0712 100644
> --- a/src/qemu/qemu_hotplug.c
> +++ b/src/qemu/qemu_hotplug.c
> @@ -4447,10 +4447,8 @@
> qemuDomainDetachVirtioDiskDevice(virQEMUDriverPtr driver,
> goto cleanup;
> }
>
> - if (!detach->info.alias) {
> - if (qemuAssignDeviceDiskAlias(vm->def, detach,
> priv->qemuCaps) < 0)
> - goto cleanup;
> - }
> + if (qemuAssignDeviceDiskAlias(vm->def, detach, priv->qemuCaps) < 0)
> + goto cleanup;
>
All the calls assigning aliases in the Detach functions are
unnecessary. At this point, all the domain's devices should have their
aliases assigned. If by any case they do not, it is an error in other
part of the libvirt code.
True - I was following the symptom though... That being calling
qemuMonitorDelDevice with a NULL detach->info.alias means
qemuMonitorTextDelDevice could dereference @devalias in the call to
qemuMonitorEscapeArg. In the json path, failure will come during
qemuMonitorJSONMakeCommand because "s:id" requires a NON NULL value in
virJSONValueObjectAddVArgs.
Anyway this just seemed to be the "easiest" adjustment especially since
no other caller checks if !*->info.alias before calling
qemuAssignDeviceDiskAlias (similar for Controller too) because the top
of each checks if already assigned, return 0.
I was going to send patches cleaning these up, but I could not decide
whether to report an error if we find a device without an alias,
or to just quietly assume that an alias. And I did not want to conflict
with Michal's series again.
Jan
Still I do believe it indicates that providing an error message is
probably better than blindly hoping things will work. I wasn't following
the user alias series that closely so I wasn't thinking about that.
I'm perfectly fine with just dropping this and the next patch since at
this point it's just Coverity noise that I can easily filter out until
something better is provided.
John
> qemuDomainMarkDeviceForRemoval(vm, &detach->info);
>
> --
> 2.13.6
>
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