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

On Wed, Mar 17, 2021 at 5:36 PM Andy Shevchenko
[off-list ref] 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

Thanks!
Menglong Dong