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From: Donald Hunter <donald.hunter@gmail•com>
To: Jakub Kicinski <kuba@kernel•org>
Cc: netdev@vger•kernel.org, "David S. Miller" <davem@davemloft•net>,
	Eric Dumazet <edumazet@google•com>,
	Paolo Abeni <pabeni@redhat•com>,
	donald.hunter@redhat•com
Subject: Re: [PATCH net-next v2 3/6] tools: ynl: Add array-nest attr decoding to ynl
Date: Wed, 22 Mar 2023 11:27:25 +0000	[thread overview]
Message-ID: <m2fs9xjaaq.fsf@gmail.com> (raw)
In-Reply-To: <20230321221809.26293ca7@kernel.org> (Jakub Kicinski's message of "Tue, 21 Mar 2023 22:18:09 -0700")

Jakub Kicinski <kuba@kernel•org> writes:

> On Sun, 19 Mar 2023 19:38:00 +0000 Donald Hunter wrote:
>> Add support for decoding nested arrays of scalars in netlink messages.
>
> example?

OVS_VPORT_ATTR_UPCALL_PID is a C array of u32 values. I can provide that
as an example in the commit message.

>> Signed-off-by: Donald Hunter <donald.hunter@gmail•com>
>> ---
>>  tools/net/ynl/lib/ynl.py | 6 ++++++
>>  1 file changed, 6 insertions(+)
>> 
>> diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py
>> index 32536e1f9064..077ba9e8dc98 100644
>> --- a/tools/net/ynl/lib/ynl.py
>> +++ b/tools/net/ynl/lib/ynl.py
>> @@ -93,6 +93,10 @@ class NlAttr:
>>      def as_bin(self):
>>          return self.raw
>>  
>> +    def as_array(self, type):
>> +        format, _ = self.type_formats[type]
>> +        return list({ x[0] for x in struct.iter_unpack(format, self.raw) })
>
> So in terms of C this treats the payload of the attr as a packed array?
> That's not what array-nest is, array-nest wraps every entry in another
> nlattr:
> https://docs.kernel.org/next/userspace-api/netlink/genetlink-legacy.html#array-nest
>
> It's not a C array dumped into an attribute.
>
> IIRC I was intending to use 'binary' for packed arrays. Still use
> sub-type to carry the type, but main type should be 'binary'.
>
> If that sounds reasonable could you document or remind me to document
> this as the expected behavior? Sub-type appears completely undocumented
> now :S

That sounds reasonable, yes. I will also rename the method to
'as_c_array'. I think it should just be restricted to scalar subtypes,
i.e. u16, u32, etc. Do you agree?

I will update the  documentation for this.

  reply	other threads:[~2023-03-22 11:55 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-19 19:37 [PATCH net-next v2 0/6] ynl: add support for user headers and struct attrs Donald Hunter
2023-03-19 19:37 ` [PATCH net-next v2 1/6] tools: ynl: Fix genlmsg header encoding formats Donald Hunter
2023-03-19 19:37 ` [PATCH net-next v2 2/6] tools: ynl: Add struct parsing to nlspec Donald Hunter
2023-03-22  5:22   ` Jakub Kicinski
2023-03-22 11:38     ` Donald Hunter
2023-03-22 18:25       ` Jakub Kicinski
2023-03-19 19:38 ` [PATCH net-next v2 3/6] tools: ynl: Add array-nest attr decoding to ynl Donald Hunter
2023-03-22  5:18   ` Jakub Kicinski
2023-03-22 11:27     ` Donald Hunter [this message]
2023-03-22 18:27       ` Jakub Kicinski
2023-03-19 19:38 ` [PATCH net-next v2 4/6] tools: ynl: Add struct " Donald Hunter
2023-03-22  5:30   ` Jakub Kicinski
2023-03-22 11:48     ` Donald Hunter
2023-03-22 18:37       ` Jakub Kicinski
2023-03-22 22:06         ` Donald Hunter
2023-03-19 19:38 ` [PATCH net-next v2 5/6] tools: ynl: Add fixed-header support " Donald Hunter
2023-03-22  5:34   ` Jakub Kicinski
2023-03-22 11:54     ` Donald Hunter
2023-03-19 19:38 ` [PATCH net-next v2 6/6] netlink: specs: add partial specification for openvswitch Donald Hunter
2023-03-23  3:50 ` [PATCH net-next v2 0/6] ynl: add support for user headers and struct attrs patchwork-bot+netdevbpf

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