netdev - Re: [PATCH v3 6/9] io_uring/cmd: Introduce SOCKET_URING_OP

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Date: Mon, 21 Aug 2023 10:52:57 -0400
From: Gabriel Krisman Bertazi <krisman@...e.de>
To: Breno Leitao <leitao@...ian.org>
Cc: sdf@...gle.com,  axboe@...nel.dk,  asml.silence@...il.com,
  willemdebruijn.kernel@...il.com,  martin.lau@...ux.dev,
  bpf@...r.kernel.org,  linux-kernel@...r.kernel.org,
  netdev@...r.kernel.org,  io-uring@...r.kernel.org,  kuba@...nel.org,
  pabeni@...hat.com
Subject: Re: [PATCH v3 6/9] io_uring/cmd: Introduce SOCKET_URING_OP_GETSOCKOPT

Breno Leitao <leitao@...ian.org> writes:

> Hello Gabriel,
>
> On Thu, Aug 17, 2023 at 02:38:46PM -0400, Gabriel Krisman Bertazi wrote:
>> Breno Leitao <leitao@...ian.org> writes:
>> 
>> > +#if defined(CONFIG_NET)
>> >  int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
>> >  {
>> >  	struct socket *sock = cmd->file->private_data;
>> > @@ -189,8 +219,16 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
>> >  		if (ret)
>> >  			return ret;
>> >  		return arg;
>> > +	case SOCKET_URING_OP_GETSOCKOPT:
>> > +		return io_uring_cmd_getsockopt(sock, cmd, issue_flags);
>> >  	default:
>> >  		return -EOPNOTSUPP;
>> >  	}
>> >  }
>> > +#else
>> > +int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
>> > +{
>> > +	return -EOPNOTSUPP;
>> > +}
>> > +#endif
>> >  EXPORT_SYMBOL_GPL(io_uring_cmd_sock);
>> 
>> The CONFIG_NET guards are unrelated and need to go in a separate commit.
>> Specially because it is not only gating getsockopt, but also the already
>> merged SOCKET_URING_OP_SIOCINQ/_OP_SIOCOUTQ.
>
> Well, so far, if CONFIG_NET is disable, and you call
> io_uring_cmd_getsockopt, the callbacks will be called and returned
> -EOPNOTSUPP.

I'm not talking about io_uring_cmd_getsockopt; that would obviously
return -EOPNOTSUPP before as well.  But you are changing
io_uring_cmd_sock, which does more things:

int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
{
        [...]
	if (!prot || !prot->ioctl)
		return -EOPNOTSUPP;

	switch (cmd->sqe->cmd_op) {
	case SOCKET_URING_OP_SIOCINQ:
		ret = prot->ioctl(sk, SIOCINQ, &arg);
		if (ret)
			return ret;
		return arg;
	case SOCKET_URING_OP_SIOCOUTQ:
		ret = prot->ioctl(sk, SIOCOUTQ, &arg);
		if (ret)
			return ret;

With your patch, these two cmd_op, are now being gated by CONFIG_NET.  I
think it makes sense for them to be gated by it, But it should
be in a separated change, or at least explained in your commit message.

> With this new patch, it will eventually call sk_getsockopt which does
> not exist in the CONFIG_NET=n world. That is why I have this
> protection now. I.e, this `#if defined(CONFIG_NET)` is only necessary now,
> since it is the first time this function (io_uring_cmd_sock) will call a
> function that does not exist if CONFIG_NET is disabled.
>
> I can split it in a different patch, if you think it makes a difference.

-- 
Gabriel Krisman Bertazi