f11e6659ce
As per RFC2461, section 6.3.6, item #2, when no routers on the matching list are known to be reachable or probably reachable we do round robin on those available routes so that we make sure to probe as many of them as possible to detect when one becomes reachable faster. Each routing table has a rwlock protecting the tree and the linked list of routes at each leaf. The round robin code executes during lookup and thus with the rwlock taken as a reader. A small local spinlock tries to provide protection but this does not work at all for two reasons: 1) The round-robin list manipulation, as coded, goes like this (with read lock held): walk routes finding head and tail spin_lock(); rotate list using head and tail spin_unlock(); While one thread is rotating the list, another thread can end up with stale values of head and tail and then proceed to corrupt the list when it gets the lock. This ends up causing the OOPS in fib6_add() later onthat many people have been hitting. 2) All the other code paths that run with the rwlock held as a reader do not expect the list to change on them, they expect it to remain completely fixed while they hold the lock in that way. So, simply stated, it is impossible to implement this correctly using a manipulation of the list without violating the rwlock locking semantics. Reimplement using a per-fib6_node round-robin pointer. This way we don't need to manipulate the list at all, and since the round-robin pointer can only ever point to real existing entries we don't need to perform any locking on the changing of the round-robin pointer itself. We only need to reset the round-robin pointer to NULL when the entry it is pointing to is removed. The idea is from Thomas Graf and it is very similar to how this was implemented before the advanced router selection code when in. Signed-off-by: David S. Miller <davem@davemloft.net>
227 lines
4.8 KiB
C
227 lines
4.8 KiB
C
/*
|
|
* Linux INET6 implementation
|
|
*
|
|
* Authors:
|
|
* Pedro Roque <roque@di.fc.ul.pt>
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#ifndef _IP6_FIB_H
|
|
#define _IP6_FIB_H
|
|
|
|
#ifdef __KERNEL__
|
|
|
|
#include <linux/ipv6_route.h>
|
|
#include <linux/rtnetlink.h>
|
|
#include <linux/spinlock.h>
|
|
#include <net/dst.h>
|
|
#include <net/flow.h>
|
|
#include <net/netlink.h>
|
|
|
|
struct rt6_info;
|
|
|
|
struct fib6_config
|
|
{
|
|
u32 fc_table;
|
|
u32 fc_metric;
|
|
int fc_dst_len;
|
|
int fc_src_len;
|
|
int fc_ifindex;
|
|
u32 fc_flags;
|
|
u32 fc_protocol;
|
|
|
|
struct in6_addr fc_dst;
|
|
struct in6_addr fc_src;
|
|
struct in6_addr fc_gateway;
|
|
|
|
unsigned long fc_expires;
|
|
struct nlattr *fc_mx;
|
|
int fc_mx_len;
|
|
|
|
struct nl_info fc_nlinfo;
|
|
};
|
|
|
|
struct fib6_node
|
|
{
|
|
struct fib6_node *parent;
|
|
struct fib6_node *left;
|
|
struct fib6_node *right;
|
|
#ifdef CONFIG_IPV6_SUBTREES
|
|
struct fib6_node *subtree;
|
|
#endif
|
|
struct rt6_info *leaf;
|
|
|
|
__u16 fn_bit; /* bit key */
|
|
__u16 fn_flags;
|
|
__u32 fn_sernum;
|
|
struct rt6_info *rr_ptr;
|
|
};
|
|
|
|
#ifndef CONFIG_IPV6_SUBTREES
|
|
#define FIB6_SUBTREE(fn) NULL
|
|
#else
|
|
#define FIB6_SUBTREE(fn) ((fn)->subtree)
|
|
#endif
|
|
|
|
/*
|
|
* routing information
|
|
*
|
|
*/
|
|
|
|
struct rt6key
|
|
{
|
|
struct in6_addr addr;
|
|
int plen;
|
|
};
|
|
|
|
struct fib6_table;
|
|
|
|
struct rt6_info
|
|
{
|
|
union {
|
|
struct dst_entry dst;
|
|
} u;
|
|
|
|
struct inet6_dev *rt6i_idev;
|
|
|
|
#define rt6i_dev u.dst.dev
|
|
#define rt6i_nexthop u.dst.neighbour
|
|
#define rt6i_expires u.dst.expires
|
|
|
|
struct fib6_node *rt6i_node;
|
|
|
|
struct in6_addr rt6i_gateway;
|
|
|
|
u32 rt6i_flags;
|
|
u32 rt6i_metric;
|
|
atomic_t rt6i_ref;
|
|
struct fib6_table *rt6i_table;
|
|
|
|
struct rt6key rt6i_dst;
|
|
struct rt6key rt6i_src;
|
|
|
|
u8 rt6i_protocol;
|
|
};
|
|
|
|
static inline struct inet6_dev *ip6_dst_idev(struct dst_entry *dst)
|
|
{
|
|
return ((struct rt6_info *)dst)->rt6i_idev;
|
|
}
|
|
|
|
struct fib6_walker_t
|
|
{
|
|
struct fib6_walker_t *prev, *next;
|
|
struct fib6_node *root, *node;
|
|
struct rt6_info *leaf;
|
|
unsigned char state;
|
|
unsigned char prune;
|
|
int (*func)(struct fib6_walker_t *);
|
|
void *args;
|
|
};
|
|
|
|
struct rt6_statistics {
|
|
__u32 fib_nodes;
|
|
__u32 fib_route_nodes;
|
|
__u32 fib_rt_alloc; /* permanent routes */
|
|
__u32 fib_rt_entries; /* rt entries in table */
|
|
__u32 fib_rt_cache; /* cache routes */
|
|
__u32 fib_discarded_routes;
|
|
};
|
|
|
|
#define RTN_TL_ROOT 0x0001
|
|
#define RTN_ROOT 0x0002 /* tree root node */
|
|
#define RTN_RTINFO 0x0004 /* node with valid routing info */
|
|
|
|
/*
|
|
* priority levels (or metrics)
|
|
*
|
|
*/
|
|
|
|
#define RTPRI_FIREWALL 8 /* Firewall control information */
|
|
#define RTPRI_FLOW 16 /* Flow based forwarding rules */
|
|
#define RTPRI_KERN_CTL 32 /* Kernel control routes */
|
|
|
|
#define RTPRI_USER_MIN 256 /* Mimimum user priority */
|
|
#define RTPRI_USER_MAX 1024 /* Maximum user priority */
|
|
|
|
#define RTPRI_KERN_DFLT 4096 /* Kernel default routes */
|
|
|
|
#define MAX_FLOW_BACKTRACE 32
|
|
|
|
|
|
typedef void (*f_pnode)(struct fib6_node *fn, void *);
|
|
|
|
struct fib6_table {
|
|
struct hlist_node tb6_hlist;
|
|
u32 tb6_id;
|
|
rwlock_t tb6_lock;
|
|
struct fib6_node tb6_root;
|
|
};
|
|
|
|
#define RT6_TABLE_UNSPEC RT_TABLE_UNSPEC
|
|
#define RT6_TABLE_MAIN RT_TABLE_MAIN
|
|
#define RT6_TABLE_DFLT RT6_TABLE_MAIN
|
|
#define RT6_TABLE_INFO RT6_TABLE_MAIN
|
|
#define RT6_TABLE_PREFIX RT6_TABLE_MAIN
|
|
|
|
#ifdef CONFIG_IPV6_MULTIPLE_TABLES
|
|
#define FIB6_TABLE_MIN 1
|
|
#define FIB6_TABLE_MAX RT_TABLE_MAX
|
|
#define RT6_TABLE_LOCAL RT_TABLE_LOCAL
|
|
#else
|
|
#define FIB6_TABLE_MIN RT_TABLE_MAIN
|
|
#define FIB6_TABLE_MAX FIB6_TABLE_MIN
|
|
#define RT6_TABLE_LOCAL RT6_TABLE_MAIN
|
|
#endif
|
|
|
|
typedef struct rt6_info *(*pol_lookup_t)(struct fib6_table *,
|
|
struct flowi *, int);
|
|
|
|
/*
|
|
* exported functions
|
|
*/
|
|
|
|
extern struct fib6_table * fib6_get_table(u32 id);
|
|
extern struct fib6_table * fib6_new_table(u32 id);
|
|
extern struct dst_entry * fib6_rule_lookup(struct flowi *fl, int flags,
|
|
pol_lookup_t lookup);
|
|
|
|
extern struct fib6_node *fib6_lookup(struct fib6_node *root,
|
|
struct in6_addr *daddr,
|
|
struct in6_addr *saddr);
|
|
|
|
struct fib6_node *fib6_locate(struct fib6_node *root,
|
|
struct in6_addr *daddr, int dst_len,
|
|
struct in6_addr *saddr, int src_len);
|
|
|
|
extern void fib6_clean_all(int (*func)(struct rt6_info *, void *arg),
|
|
int prune, void *arg);
|
|
|
|
extern int fib6_add(struct fib6_node *root,
|
|
struct rt6_info *rt,
|
|
struct nl_info *info);
|
|
|
|
extern int fib6_del(struct rt6_info *rt,
|
|
struct nl_info *info);
|
|
|
|
extern void inet6_rt_notify(int event, struct rt6_info *rt,
|
|
struct nl_info *info);
|
|
|
|
extern void fib6_run_gc(unsigned long dummy);
|
|
|
|
extern void fib6_gc_cleanup(void);
|
|
|
|
extern void fib6_init(void);
|
|
|
|
extern void fib6_rules_init(void);
|
|
extern void fib6_rules_cleanup(void);
|
|
extern int fib6_rules_dump(struct sk_buff *,
|
|
struct netlink_callback *);
|
|
|
|
#endif
|
|
#endif
|