linux-kernel - Re: [PATCH net-next v6 01/18] net: Declare MSG_SPLICE

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Message-ID: <20230413005129.GZ3390869@ZenIV>
Date:   Thu, 13 Apr 2023 01:51:29 +0100
From:   Al Viro <viro@...iv.linux.org.uk>
To:     David Howells <dhowells@...hat.com>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        David Ahern <dsahern@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Christoph Hellwig <hch@...radead.org>,
        Jens Axboe <axboe@...nel.dk>, Jeff Layton <jlayton@...nel.org>,
        Christian Brauner <brauner@...nel.org>,
        Chuck Lever III <chuck.lever@...cle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next v6 01/18] net: Declare MSG_SPLICE_PAGES internal
 sendmsg() flag

On Tue, Apr 11, 2023 at 05:08:45PM +0100, David Howells wrote:

> @@ -2483,6 +2484,7 @@ static int ____sys_sendmsg(struct socket *sock, struct msghdr *msg_sys,
>  	}
>  	msg_sys->msg_flags = flags;
>  
> +	flags &= ~MSG_INTERNAL_SENDMSG_FLAGS;
>  	if (sock->file->f_flags & O_NONBLOCK)
>  		msg_sys->msg_flags |= MSG_DONTWAIT;

A bit too late, innit?  There's no users of 'flags' downstream of that
assignment to ->msg_flags, so your &= is a no-op; it should be done
*before* that assignment...