Use unsigned timeout in cmdMigrateSetMaxDowntime

[libvirt] [PATCH] Use unsigned timeout in cmdMigrateSetMaxDowntime

Posted by Scott Garfinkle 7 years, 10 months ago

While looking to implement a migrate-getmaxdowntime command (coming),
I noticed that the setmaxdowntime is incorrectly looking at its
parameter as a signed longlong. Not sure how that got past gcc, but
here's a simple patch to make the command line parsing and the parameter to
the worker functions all have the correct (unsigned) type.

Signed-off-by: Scott Garfinkle <seg@us.ibm.com>
---
 tools/virsh-domain.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
index 5311a57..0d21fe7 100644
--- a/tools/virsh-domain.c
+++ b/tools/virsh-domain.c
@@ -10696,13 +10696,13 @@ static bool
 cmdMigrateSetMaxDowntime(vshControl *ctl, const vshCmd *cmd)
 {
     virDomainPtr dom = NULL;
-    long long downtime = 0;
+    unsigned long long downtime = 0;
     bool ret = false;
 
     if (!(dom = virshCommandOptDomain(ctl, cmd, NULL)))
         return false;
 
-    if (vshCommandOptLongLong(ctl, cmd, "downtime", &downtime) < 0)
+    if (vshCommandOptULongLong(ctl, cmd, "downtime", &downtime) < 0)
         goto done;
     if (downtime < 1) {
         vshError(ctl, "%s", _("migrate: Invalid downtime"));
-- 
1.8.3.1

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Re: [libvirt] [PATCH] Use unsigned timeout in cmdMigrateSetMaxDowntime

Posted by John Ferlan 7 years, 10 months ago

On 06/27/2017 11:19 AM, Scott Garfinkle wrote:
> While looking to implement a migrate-getmaxdowntime command (coming),
> I noticed that the setmaxdowntime is incorrectly looking at its
> parameter as a signed longlong. Not sure how that got past gcc, but
> here's a simple patch to make the command line parsing and the parameter to
> the worker functions all have the correct (unsigned) type.
> 
> Signed-off-by: Scott Garfinkle <seg@us.ibm.com>
> ---
>  tools/virsh-domain.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 

"For some commands" allowing a -1 provides a mechanism to set an almost
infinite time without having to type such a large value.  Still in this
case since, the "downtime < 1" check immediately follows it seems that
wouldn't be the case here!

Looking at QEMU code briefly - I do note the QEMU set downtime (and
speed) commands that end up getting called are listed as "deprecated" in
favor of migrate-set-parameters (downtime-limit and max-bandwidth, since
QEMU 2.8).  So while you're at thinking about a getmaxdowntime type
functionality maybe you'd want to give that a go as well (of course
you'd have to add capabilities to detect when it was implemented using
set-parameters)...

In any case,

Reviewed-by: John Ferlan <jferlan@redhat.com>

I'll push in a bit...

Tks -

John

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Re: [libvirt] [PATCH] Use unsigned timeout in cmdMigrateSetMaxDowntime

Posted by Scott Garfinkle 7 years, 10 months ago

John Ferlan <jferlan@redhat.com> wrote on 07/10/2017 06:41:34 AM:

> From: John Ferlan <jferlan@redhat.com>
> To: Scott Garfinkle <seg@us.ibm.com>, libvir-list@redhat.com
> Date: 07/10/2017 06:41 AM
> Subject: Re: [libvirt] [PATCH] Use unsigned timeout in 
> cmdMigrateSetMaxDowntime
> 
> 
> 
> On 06/27/2017 11:19 AM, Scott Garfinkle wrote:
> > While looking to implement a migrate-getmaxdowntime command (coming),
> > I noticed that the setmaxdowntime is incorrectly looking at its
> > parameter as a signed longlong. Not sure how that got past gcc, but
> > here's a simple patch to make the command line parsing and the 
parameter to
> > the worker functions all have the correct (unsigned) type.
> > 
> > Signed-off-by: Scott Garfinkle <seg@us.ibm.com>
> > ---
> >  tools/virsh-domain.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> 
> "For some commands" allowing a -1 provides a mechanism to set an almost
> infinite time without having to type such a large value.  Still in this
> case since, the "downtime < 1" check immediately follows it seems that
> wouldn't be the case here!
Yes, and maybe removing that check would have been a better alternative? 
Still, thanks.
 
> Looking at QEMU code briefly - I do note the QEMU set downtime (and
> speed) commands that end up getting called are listed as "deprecated" in
> favor of migrate-set-parameters (downtime-limit and max-bandwidth, since
> QEMU 2.8).  So while you're at thinking about a getmaxdowntime type
> functionality maybe you'd want to give that a go as well (of course
> you'd have to add capabilities to detect when it was implemented using
> set-parameters)...

Thanks for pointing that out. So, I have patches to implement the 
get-maxdowntime, which would seem to be a separate but related effort. 
Being a newcomer to the code, I'll what are probably obvious questions: is 
the concern that qemu will eventually just stop providing that interface? 
Or, is there something inherently useful about changing the set-* 
commands? Otherwise, I'm not sure what the value to the code is of 
changing the already-working set commands.

regards, Scott Garfinkle

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