From 7b204afd45820fc21b5983205ad535c6b8088765 Mon Sep 17 00:00:00 2001 From: Robert Olsson Date: Mon, 20 Mar 2006 17:18:53 -0800 Subject: [PATCH] [IPV4]: Use RCU locking in fib_rules. Signed-off-by: Robert Olsson Signed-off-by: David S. Miller --- net/ipv4/fib_rules.c | 113 ++++++++++++++++++++++++++----------------- 1 file changed, 68 insertions(+), 45 deletions(-) diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c index 0dd4d06e456d..7b462a39aa4d 100644 --- a/net/ipv4/fib_rules.c +++ b/net/ipv4/fib_rules.c @@ -40,6 +40,8 @@ #include #include #include +#include +#include #include #include @@ -52,7 +54,7 @@ struct fib_rule { - struct fib_rule *r_next; + struct hlist_node hlist; atomic_t r_clntref; u32 r_preference; unsigned char r_table; @@ -75,6 +77,7 @@ struct fib_rule #endif char r_ifname[IFNAMSIZ]; int r_dead; + struct rcu_head rcu; }; static struct fib_rule default_rule = { @@ -85,7 +88,6 @@ static struct fib_rule default_rule = { }; static struct fib_rule main_rule = { - .r_next = &default_rule, .r_clntref = ATOMIC_INIT(2), .r_preference = 0x7FFE, .r_table = RT_TABLE_MAIN, @@ -93,23 +95,24 @@ static struct fib_rule main_rule = { }; static struct fib_rule local_rule = { - .r_next = &main_rule, .r_clntref = ATOMIC_INIT(2), .r_table = RT_TABLE_LOCAL, .r_action = RTN_UNICAST, }; -static struct fib_rule *fib_rules = &local_rule; -static DEFINE_RWLOCK(fib_rules_lock); +struct hlist_head fib_rules; + +/* writer func called from netlink -- rtnl_sem hold*/ int inet_rtm_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) { struct rtattr **rta = arg; struct rtmsg *rtm = NLMSG_DATA(nlh); - struct fib_rule *r, **rp; + struct fib_rule *r; + struct hlist_node *node; int err = -ESRCH; - for (rp=&fib_rules; (r=*rp) != NULL; rp=&r->r_next) { + hlist_for_each_entry(r, node, &fib_rules, hlist) { if ((!rta[RTA_SRC-1] || memcmp(RTA_DATA(rta[RTA_SRC-1]), &r->r_src, 4) == 0) && rtm->rtm_src_len == r->r_src_len && rtm->rtm_dst_len == r->r_dst_len && @@ -126,10 +129,8 @@ int inet_rtm_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) if (r == &local_rule) break; - write_lock_bh(&fib_rules_lock); - *rp = r->r_next; + hlist_del_rcu(&r->hlist); r->r_dead = 1; - write_unlock_bh(&fib_rules_lock); fib_rule_put(r); err = 0; break; @@ -150,21 +151,30 @@ static struct fib_table *fib_empty_table(void) return NULL; } +static inline void fib_rule_put_rcu(struct rcu_head *head) +{ + struct fib_rule *r = container_of(head, struct fib_rule, rcu); + kfree(r); +} + void fib_rule_put(struct fib_rule *r) { if (atomic_dec_and_test(&r->r_clntref)) { if (r->r_dead) - kfree(r); + call_rcu(&r->rcu, fib_rule_put_rcu); else printk("Freeing alive rule %p\n", r); } } +/* writer func called from netlink -- rtnl_sem hold*/ + int inet_rtm_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) { struct rtattr **rta = arg; struct rtmsg *rtm = NLMSG_DATA(nlh); - struct fib_rule *r, *new_r, **rp; + struct fib_rule *r, *new_r, *last = NULL; + struct hlist_node *node = NULL; unsigned char table_id; if (rtm->rtm_src_len > 32 || rtm->rtm_dst_len > 32 || @@ -188,6 +198,7 @@ int inet_rtm_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) if (!new_r) return -ENOMEM; memset(new_r, 0, sizeof(*new_r)); + if (rta[RTA_SRC-1]) memcpy(&new_r->r_src, RTA_DATA(rta[RTA_SRC-1]), 4); if (rta[RTA_DST-1]) @@ -220,28 +231,28 @@ int inet_rtm_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg) if (rta[RTA_FLOW-1]) memcpy(&new_r->r_tclassid, RTA_DATA(rta[RTA_FLOW-1]), 4); #endif + r = container_of(fib_rules.first, struct fib_rule, hlist); - rp = &fib_rules; if (!new_r->r_preference) { - r = fib_rules; - if (r && (r = r->r_next) != NULL) { - rp = &fib_rules->r_next; + if (r && r->hlist.next != NULL) { + r = container_of(r->hlist.next, struct fib_rule, hlist); if (r->r_preference) new_r->r_preference = r->r_preference - 1; } } - while ( (r = *rp) != NULL ) { + hlist_for_each_entry(r, node, &fib_rules, hlist) { if (r->r_preference > new_r->r_preference) break; - rp = &r->r_next; + last = r; } - - new_r->r_next = r; atomic_inc(&new_r->r_clntref); - write_lock_bh(&fib_rules_lock); - *rp = new_r; - write_unlock_bh(&fib_rules_lock); + + if (last) + hlist_add_after_rcu(&last->hlist, &new_r->hlist); + else + hlist_add_before_rcu(&new_r->hlist, &r->hlist); + return 0; } @@ -254,30 +265,30 @@ u32 fib_rules_tclass(struct fib_result *res) } #endif +/* callers should hold rtnl semaphore */ static void fib_rules_detach(struct net_device *dev) { + struct hlist_node *node; struct fib_rule *r; - for (r=fib_rules; r; r=r->r_next) { - if (r->r_ifindex == dev->ifindex) { - write_lock_bh(&fib_rules_lock); + hlist_for_each_entry(r, node, &fib_rules, hlist) { + if (r->r_ifindex == dev->ifindex) r->r_ifindex = -1; - write_unlock_bh(&fib_rules_lock); - } + } } +/* callers should hold rtnl semaphore */ + static void fib_rules_attach(struct net_device *dev) { + struct hlist_node *node; struct fib_rule *r; - for (r=fib_rules; r; r=r->r_next) { - if (r->r_ifindex == -1 && strcmp(dev->name, r->r_ifname) == 0) { - write_lock_bh(&fib_rules_lock); + hlist_for_each_entry(r, node, &fib_rules, hlist) { + if (r->r_ifindex == -1 && strcmp(dev->name, r->r_ifname) == 0) r->r_ifindex = dev->ifindex; - write_unlock_bh(&fib_rules_lock); - } } } @@ -286,14 +297,17 @@ int fib_lookup(const struct flowi *flp, struct fib_result *res) int err; struct fib_rule *r, *policy; struct fib_table *tb; + struct hlist_node *node; u32 daddr = flp->fl4_dst; u32 saddr = flp->fl4_src; FRprintk("Lookup: %u.%u.%u.%u <- %u.%u.%u.%u ", NIPQUAD(flp->fl4_dst), NIPQUAD(flp->fl4_src)); - read_lock(&fib_rules_lock); - for (r = fib_rules; r; r=r->r_next) { + + rcu_read_lock(); + + hlist_for_each_entry_rcu(r, node, &fib_rules, hlist) { if (((saddr^r->r_src) & r->r_srcmask) || ((daddr^r->r_dst) & r->r_dstmask) || (r->r_tos && r->r_tos != flp->fl4_tos) || @@ -309,14 +323,14 @@ FRprintk("tb %d r %d ", r->r_table, r->r_action); policy = r; break; case RTN_UNREACHABLE: - read_unlock(&fib_rules_lock); + rcu_read_unlock(); return -ENETUNREACH; default: case RTN_BLACKHOLE: - read_unlock(&fib_rules_lock); + rcu_read_unlock(); return -EINVAL; case RTN_PROHIBIT: - read_unlock(&fib_rules_lock); + rcu_read_unlock(); return -EACCES; } @@ -327,16 +341,16 @@ FRprintk("tb %d r %d ", r->r_table, r->r_action); res->r = policy; if (policy) atomic_inc(&policy->r_clntref); - read_unlock(&fib_rules_lock); + rcu_read_unlock(); return 0; } if (err < 0 && err != -EAGAIN) { - read_unlock(&fib_rules_lock); + rcu_read_unlock(); return err; } } FRprintk("FAILURE\n"); - read_unlock(&fib_rules_lock); + rcu_read_unlock(); return -ENETUNREACH; } @@ -414,20 +428,25 @@ rtattr_failure: return -1; } +/* callers should hold rtnl semaphore */ + int inet_dump_rules(struct sk_buff *skb, struct netlink_callback *cb) { - int idx; + int idx = 0; int s_idx = cb->args[0]; struct fib_rule *r; + struct hlist_node *node; + + rcu_read_lock(); + hlist_for_each_entry(r, node, &fib_rules, hlist) { - read_lock(&fib_rules_lock); - for (r=fib_rules, idx=0; r; r = r->r_next, idx++) { if (idx < s_idx) continue; if (inet_fill_rule(skb, r, cb, NLM_F_MULTI) < 0) break; + idx++; } - read_unlock(&fib_rules_lock); + rcu_read_unlock(); cb->args[0] = idx; return skb->len; @@ -435,5 +454,9 @@ int inet_dump_rules(struct sk_buff *skb, struct netlink_callback *cb) void __init fib_rules_init(void) { + INIT_HLIST_HEAD(&fib_rules); + hlist_add_head(&local_rule.hlist, &fib_rules); + hlist_add_after(&local_rule.hlist, &main_rule.hlist); + hlist_add_after(&main_rule.hlist, &default_rule.hlist); register_netdevice_notifier(&fib_rules_notifier); } -- 2.20.1