Re: [patch 7/8] fdmap v2 - implement sys_socket2

[David Miller <davem@davemloft.net>]

From: Davide Libenzi <davidel@xmailserver.org>
Date: Wed, 06 Jun 2007 15:30:31 -0700

> This patch implement a new syscall sys_socket2(), that accepts an
> extra "flags" parameter:
> 
> int socket2(int domain, int type, int protocol, int flags);
> 
> The flags parameter is used to pass extra flags to the kernel, and is
> at the moment used to select the file descriptor allocations inside
> the non-sequential area (O_NONSEQFD). The remaining parameters are
> exactly the same as the ones of sys_socket().
> The sys_accept() system call has been modified to return a file
> descriptor inside the non-sequential area, if the listening fd is.
> The sys_socketcall() system call has been also changed to support
> a new SYS_SOCKET2 indentifier.
> 
> Signed-off-by: Davide Libenzi <davidel@xmailserver.org>

Since the valid range of "domain" values is quite small,
we could avoid the new system call by cribbing some of the
upper bits of the 'domain' argument.

Valid existing programs pass in valid 'domain' values and
thus will not set any of the new flags.

Just an idea.