Re: [PATCH v4 07/10] io_uring/cmd: return -EOPNOTSUPP if net is disabled

From: Gabriel Krisman Bertazi <krisman@suse.de>
To: Breno Leitao <leitao@debian.org>
Cc: sdf@google.com, axboe@kernel.dk, asml.silence@gmail.com,
	willemdebruijn.kernel@gmail.com, martin.lau@linux.dev,
	bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, io-uring@vger.kernel.org,
	kuba@kernel.org, pabeni@redhat.com
Subject: Re: [PATCH v4 07/10] io_uring/cmd: return -EOPNOTSUPP if net is disabled
Date: Tue, 05 Sep 2023 08:32:15 -0400	[thread overview]
Message-ID: <871qfcby28.fsf@suse.de> (raw)
In-Reply-To: <20230904162504.1356068-8-leitao@debian.org> (Breno Leitao's message of "Mon, 4 Sep 2023 09:25:00 -0700")

Breno Leitao <leitao@debian.org> writes:

> Protect io_uring_cmd_sock() to be called if CONFIG_NET is not set. If
> network is not enabled, but io_uring is, then we want to return
> -EOPNOTSUPP for any possible socket operation.
>
> This is helpful because io_uring_cmd_sock() can now call functions that
> only exits if CONFIG_NET is enabled without having #ifdef CONFIG_NET
> inside the function itself.
>
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>  io_uring/uring_cmd.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
> index 60f843a357e0..6a91e1af7d05 100644
> --- a/io_uring/uring_cmd.c
> +++ b/io_uring/uring_cmd.c
> @@ -167,6 +167,7 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
>  }
>  EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed);
>  
> +#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;
> @@ -192,4 +193,11 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
>  		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);

It doesn't make much sense to export the symbol on the !CONFIG_NET case.
Usually, you'd make it a 'static inline' in the header file (even though
it won't be ever inlined in this case):

in include/linux/io_uring.h:

#if defined(CONFIG_NET)
int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags);
#else
static inline int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
{
	return -EOPNOTSUPP;
}
#endif

But this is a minor detail. I'd say to consider doing it if you end up doing
another spin of the patchset.  Other than that, looks good to me.

Thanks,

-- 
Gabriel Krisman Bertazi