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

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Date: Tue, 05 Sep 2023 08:32:15 -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 v4 07/10] io_uring/cmd: return -EOPNOTSUPP if net is
 disabled

Breno Leitao <leitao@...ian.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@...ian.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