Re: [Qemu-devel] [Qemu-block] [PATCH 4/7] block: convert ThrottleGroup to object with QOM

[Stefan Hajnoczi]

On Tue, Jul 25, 2017 at 01:29:08PM +0300, Manos Pitsidianakis wrote:
> On Mon, Jul 24, 2017 at 04:12:47PM +0100, Stefan Hajnoczi wrote:
> > On Fri, Jul 14, 2017 at 12:45:18PM +0300, Manos Pitsidianakis wrote:
> > > ThrottleGroup is converted to an object. This will allow the future
> > > throttle block filter drive easy creation and configuration of throttle
> > > groups in QMP and cli.
> > > 
> > > A new QAPI struct, ThrottleLimits, is introduced to provide a shared
> > > struct for all throttle configuration needs in QMP.
> > > 
> > > ThrottleGroups can be created via CLI as
> > >     -object throttling-group,id=foo,x-iops-total=100,x-..
> > 
> > Please make the QOM name and struct name consistent.  Either
> > ThrottleGroup/throttle-group or ThrottlingGroup/throttling-group but not
> > ThrottleGroup/throttling-group.
> 
> I did this on purpose because current throttling has ThrottleGroup
> internally and throttling.group in the command line. Should we keep this
> only in legacy and make it throttle-group everywhere?

I don't see a compatibility issue because -drive throttling.group= is a
-drive property while THROTTLE_GROUP ("throttling-group") is a QOM class
name.  They are unrelated and the QOM convention is for the
typedef/struct name (ThrottleGroup) to be consistent with the QOM class
name.

Therefore it should be safe to use "throttle-group" as the QOM class
name instead of "throttling-group".

> > > +    visit_type_int64(v, name, &value, &local_err);
> > > +    if (local_err) {
> > > +        goto fail;
> > > +    }
> > > +    if (value < 0) {
> > > +        error_setg(&local_err, "Property value must be in range "
> > > +                               "[0, %"PRId64"]", INT64_MAX);
> > 
> > Please print the maximum value relevant to the actual field type instead
> > of INT64_MAX.
> 
> This checks the limits of the int64 field you give to QOM. I think you mean
> in the value assignment to each field that follows? In any case, since
> unsigned is the only smaller field we could convert it to uint64_t/uint32_t
> internally.

I'm saying that UNSIGNED fields are silently truncated if the value is
larger than UINT_MAX, and also that the error message is misleading
since UNSIGNED fields cannot take values in the whole range we print.

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