Re: [PATCH v4 RESEND net-next] net: socket: use BIT() for MSG_*

From: Menglong Dong
Date: Wed Mar 17 2021 - 09:54:21 EST

On Wed, Mar 17, 2021 at 5:36 PM Andy Shevchenko
<andy.shevchenko@xxxxxxxxx> wrote:
> The problematic code is negation of the flags when it's done in
> operations like &.
> It maybe fixed by swapping positions of the arguments, i.e. ~(FOO |
> BAR) & flags.
> All this is a beast called "integer promotions" in the C standard.
> The best is to try to get flags to be unsigned. By how invasive it may be?

Seems that the inconsistent usages of 'msg_flags' is a lot, for example the
'recvmsg()' in 'struct proto' and 'recvmsg()' in 'struct proto_ops':

int (*recvmsg)(struct sock *sk, struct msghdr *msg,
size_t len, int noblock, int flags,
int *addr_len);

This function prototype is used in many places, It's not easy to fix them.
This patch is already reverted, and I think maybe
I can resend it after I fix these 'int' flags.

> --
> With Best Regards,
> Andy Shevchenko

Menglong Dong