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Message-ID: <20210317150240.GA159538@roeck-us.net>
Date: Wed, 17 Mar 2021 08:02:40 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Menglong Dong <menglong8.dong@...il.com>
Cc: Andy Shevchenko <andy.shevchenko@...il.com>,
Jakub Kicinski <kuba@...nel.org>,
"davem@...emloft.net" <davem@...emloft.net>,
"axboe@...nel.dk" <axboe@...nel.dk>,
"viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
"herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
"dong.menglong@....com.cn" <dong.menglong@....com.cn>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH v4 RESEND net-next] net: socket: use BIT() for MSG_*
On Wed, Mar 17, 2021 at 09:53:23PM +0800, Menglong Dong wrote:
> On Wed, Mar 17, 2021 at 5:36 PM Andy Shevchenko
> <andy.shevchenko@...il.com> 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.
Also, flags is used in several other functions, not just recvmsg.
> This patch is already reverted, and I think maybe
> I can resend it after I fix these 'int' flags.
I would suggest to consult with Dave on that. While much of the conversion
could be handled automatically with coccinelle, it touches a lot of files.
I don't think that is worth the effort (or risk).
Guenter
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