Re: [PATCH] hw: forbid DEFINE_PROP_ARRAY for user creatable devices

[Kevin Wolf]

Am 08.09.2023 um 11:29 hat Daniel P. Berrangé geschrieben:
> The DEFINE_PROP_ARRAY macro is a clever trick for defining array
> properties. It initially creates a property "len-$FOO". When that
> property is set, then it creates a sequence "$FOO[NN]" for NN
> in the range 0 to "len-$FOO".
> 
> The intended usage for this was to simplify code for internal
> devices, however, it crept into use for user creatable devices
> when the 'rocker' network device used it.
> 
> This relied on the user specifying the len property first on
> the -device comand line, and the args being processed in-order.
> The latter was broken[1] when -device was converted from QemuOpts
> to QDict[2], as ordering of loading properties was no longer
> guaranteed to match user specified ordering.
> 
> This change poisons the setter for "len-$FOO" such that it raises
> an error when used with a user creatable device.
> 
> This allows DEFINE_PROP_ARRAY to remain exclusively for internal
> devices, since code can ensure properties are set in the correct
> ordering.
> 
> [1] https://gitlab.com/qemu-project/qemu/-/issues/1090
> [2] f3558b1b763683bb877f7dd5b282469cdadc65c3
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

NACK.

This doesn't fix the problem, but breaks rocker for good. As I said, I'm
working on proper array support and will send patches soon.

Kevin