linux/drivers/net/team/team_mode_random.c
Daniel Borkmann f337db64af random32: add prandom_u32_max and convert open coded users
Many functions have open coded a function that returns a random
number in range [0,N-1]. Under the assumption that we have a PRNG
such as taus113 with being well distributed in [0, ~0U] space,
we can implement such a function as uword t = (n*m')>>32, where
m' is a random number obtained from PRNG, n the right open interval
border and t our resulting random number, with n,m',t in u32 universe.

Lets go with Joe and simply call it prandom_u32_max(), although
technically we have an right open interval endpoint, but that we
have documented. Other users can further be migrated to the new
prandom_u32_max() function later on; for now, we need to make sure
to migrate reciprocal_divide() users for the reciprocal_divide()
follow-up fixup since their function signatures are going to change.

Joint work with Hannes Frederic Sowa.

Cc: Jakub Zawadzki <darkjames-ws@darkjames.pl>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-01-21 23:17:20 -08:00

68 lines
1.6 KiB
C

/*
* drivers/net/team/team_mode_random.c - Random mode for team
* Copyright (c) 2013 Jiri Pirko <jiri@resnulli.us>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/if_team.h>
static bool rnd_transmit(struct team *team, struct sk_buff *skb)
{
struct team_port *port;
int port_index;
port_index = prandom_u32_max(team->en_port_count);
port = team_get_port_by_index_rcu(team, port_index);
if (unlikely(!port))
goto drop;
port = team_get_first_port_txable_rcu(team, port);
if (unlikely(!port))
goto drop;
if (team_dev_queue_xmit(team, port, skb))
return false;
return true;
drop:
dev_kfree_skb_any(skb);
return false;
}
static const struct team_mode_ops rnd_mode_ops = {
.transmit = rnd_transmit,
.port_enter = team_modeop_port_enter,
.port_change_dev_addr = team_modeop_port_change_dev_addr,
};
static const struct team_mode rnd_mode = {
.kind = "random",
.owner = THIS_MODULE,
.ops = &rnd_mode_ops,
};
static int __init rnd_init_module(void)
{
return team_mode_register(&rnd_mode);
}
static void __exit rnd_cleanup_module(void)
{
team_mode_unregister(&rnd_mode);
}
module_init(rnd_init_module);
module_exit(rnd_cleanup_module);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>");
MODULE_DESCRIPTION("Random mode for team");
MODULE_ALIAS("team-mode-random");