diff options
Diffstat (limited to 'net/ipv4/multipath_drr.c')
| -rw-r--r-- | net/ipv4/multipath_drr.c | 265 |
1 files changed, 265 insertions, 0 deletions
diff --git a/net/ipv4/multipath_drr.c b/net/ipv4/multipath_drr.c new file mode 100644 index 00000000000..9349686131f --- /dev/null +++ b/net/ipv4/multipath_drr.c @@ -0,0 +1,265 @@ +/* + * Device round robin policy for multipath. + * + * + * Version: $Id: multipath_drr.c,v 1.1.2.1 2004/09/16 07:42:34 elueck Exp $ + * + * Authors: Einar Lueck <elueck@de.ibm.com><lkml@einar-lueck.de> + * + * 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/config.h> +#include <asm/system.h> +#include <asm/uaccess.h> +#include <linux/types.h> +#include <linux/sched.h> +#include <linux/errno.h> +#include <linux/timer.h> +#include <linux/mm.h> +#include <linux/kernel.h> +#include <linux/fcntl.h> +#include <linux/stat.h> +#include <linux/socket.h> +#include <linux/in.h> +#include <linux/inet.h> +#include <linux/netdevice.h> +#include <linux/inetdevice.h> +#include <linux/igmp.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include <linux/mroute.h> +#include <linux/init.h> +#include <net/ip.h> +#include <net/protocol.h> +#include <linux/skbuff.h> +#include <net/sock.h> +#include <net/icmp.h> +#include <net/udp.h> +#include <net/raw.h> +#include <linux/notifier.h> +#include <linux/if_arp.h> +#include <linux/netfilter_ipv4.h> +#include <net/ipip.h> +#include <net/checksum.h> +#include <net/ip_mp_alg.h> + +struct multipath_device { + int ifi; /* interface index of device */ + atomic_t usecount; + int allocated; +}; + +#define MULTIPATH_MAX_DEVICECANDIDATES 10 + +static struct multipath_device state[MULTIPATH_MAX_DEVICECANDIDATES]; +static DEFINE_SPINLOCK(state_lock); +static struct rtable *last_selection = NULL; + +static int inline __multipath_findslot(void) +{ + int i; + + for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) { + if (state[i].allocated == 0) + return i; + } + return -1; +} + +static int inline __multipath_finddev(int ifindex) +{ + int i; + + for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) { + if (state[i].allocated != 0 && + state[i].ifi == ifindex) + return i; + } + return -1; +} + +static int drr_dev_event(struct notifier_block *this, + unsigned long event, void *ptr) +{ + struct net_device *dev = ptr; + int devidx; + + switch (event) { + case NETDEV_UNREGISTER: + case NETDEV_DOWN: + spin_lock_bh(&state_lock); + + devidx = __multipath_finddev(dev->ifindex); + if (devidx != -1) { + state[devidx].allocated = 0; + state[devidx].ifi = 0; + atomic_set(&state[devidx].usecount, 0); + } + + spin_unlock_bh(&state_lock); + break; + }; + + return NOTIFY_DONE; +} + +struct notifier_block drr_dev_notifier = { + .notifier_call = drr_dev_event, +}; + +static void drr_remove(struct rtable *rt) +{ + if (last_selection == rt) + last_selection = NULL; +} + +static void drr_safe_inc(atomic_t *usecount) +{ + int n; + + atomic_inc(usecount); + + n = atomic_read(usecount); + if (n <= 0) { + int i; + + spin_lock_bh(&state_lock); + + for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) + atomic_set(&state[i].usecount, 0); + + spin_unlock_bh(&state_lock); + } +} + +static void drr_select_route(const struct flowi *flp, + struct rtable *first, struct rtable **rp) +{ + struct rtable *nh, *result, *cur_min; + int min_usecount = -1; + int devidx = -1; + int cur_min_devidx = -1; + + /* if necessary and possible utilize the old alternative */ + if ((flp->flags & FLOWI_FLAG_MULTIPATHOLDROUTE) != 0 && + last_selection != NULL) { + result = last_selection; + *rp = result; + return; + } + + /* 1. make sure all alt. nexthops have the same GC related data */ + /* 2. determine the new candidate to be returned */ + result = NULL; + cur_min = NULL; + for (nh = rcu_dereference(first); nh; + nh = rcu_dereference(nh->u.rt_next)) { + if ((nh->u.dst.flags & DST_BALANCED) != 0 && + multipath_comparekeys(&nh->fl, flp)) { + int nh_ifidx = nh->u.dst.dev->ifindex; + + nh->u.dst.lastuse = jiffies; + nh->u.dst.__use++; + if (result != NULL) + continue; + + /* search for the output interface */ + + /* this is not SMP safe, only add/remove are + * SMP safe as wrong usecount updates have no big + * impact + */ + devidx = __multipath_finddev(nh_ifidx); + if (devidx == -1) { + /* add the interface to the array + * SMP safe + */ + spin_lock_bh(&state_lock); + + /* due to SMP: search again */ + devidx = __multipath_finddev(nh_ifidx); + if (devidx == -1) { + /* add entry for device */ + devidx = __multipath_findslot(); + if (devidx == -1) { + /* unlikely but possible */ + continue; + } + + state[devidx].allocated = 1; + state[devidx].ifi = nh_ifidx; + atomic_set(&state[devidx].usecount, 0); + min_usecount = 0; + } + + spin_unlock_bh(&state_lock); + } + + if (min_usecount == 0) { + /* if the device has not been used it is + * the primary target + */ + drr_safe_inc(&state[devidx].usecount); + result = nh; + } else { + int count = + atomic_read(&state[devidx].usecount); + + if (min_usecount == -1 || + count < min_usecount) { + cur_min = nh; + cur_min_devidx = devidx; + min_usecount = count; + } + } + } + } + + if (!result) { + if (cur_min) { + drr_safe_inc(&state[cur_min_devidx].usecount); + result = cur_min; + } else { + result = first; + } + } + + *rp = result; + last_selection = result; +} + +static struct ip_mp_alg_ops drr_ops = { + .mp_alg_select_route = drr_select_route, + .mp_alg_remove = drr_remove, +}; + +static int __init drr_init(void) +{ + int err = register_netdevice_notifier(&drr_dev_notifier); + + if (err) + return err; + + err = multipath_alg_register(&drr_ops, IP_MP_ALG_RR); + if (err) + goto fail; + + return 0; + +fail: + unregister_netdevice_notifier(&drr_dev_notifier); + return err; +} + +static void __exit drr_exit(void) +{ + unregister_netdevice_notifier(&drr_dev_notifier); + multipath_alg_unregister(&drr_ops, IP_MP_ALG_DRR); +} + +module_init(drr_init); +module_exit(drr_exit); |