From ef9a9d1183b36fbf3de327f44596533b770c3005 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 23 Oct 2009 17:51:26 +0000 Subject: [PATCH] ipv6 sit: RCU conversion phase I SIT tunnels use one rwlock to protect their prl entries. This first patch adds RCU locking for prl management, with standard call_rcu() calls. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/ipip.h | 1 + net/ipv6/sit.c | 73 +++++++++++++++++++++++++++++++++++++----------------- 2 files changed, 51 insertions(+), 23 deletions(-) diff --git a/include/net/ipip.h b/include/net/ipip.h index 86f1c8b..b3db2fd 100644 --- a/include/net/ipip.h +++ b/include/net/ipip.h @@ -45,6 +45,7 @@ struct ip_tunnel_prl_entry struct ip_tunnel_prl_entry *next; __be32 addr; u16 flags; + struct rcu_head rcu_head; }; #define IPTUNNEL_XMIT() do { \ diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index 510d31f..8cdcc2ad 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -240,15 +240,22 @@ failed: return NULL; } +static DEFINE_SPINLOCK(ipip6_prl_lock); + +#define for_each_prl_rcu(start) \ + for (prl = rcu_dereference(start); \ + prl; \ + prl = rcu_dereference(prl->next)) + static struct ip_tunnel_prl_entry * __ipip6_tunnel_locate_prl(struct ip_tunnel *t, __be32 addr) { - struct ip_tunnel_prl_entry *p = (struct ip_tunnel_prl_entry *)NULL; + struct ip_tunnel_prl_entry *prl; - for (p = t->prl; p; p = p->next) - if (p->addr == addr) + for_each_prl_rcu(t->prl) + if (prl->addr == addr) break; - return p; + return prl; } @@ -273,7 +280,7 @@ static int ipip6_tunnel_get_prl(struct ip_tunnel *t, kcalloc(cmax, sizeof(*kp), GFP_KERNEL) : NULL; - read_lock(&ipip6_lock); + rcu_read_lock(); ca = t->prl_count < cmax ? t->prl_count : cmax; @@ -291,7 +298,7 @@ static int ipip6_tunnel_get_prl(struct ip_tunnel *t, } c = 0; - for (prl = t->prl; prl; prl = prl->next) { + for_each_prl_rcu(t->prl) { if (c >= cmax) break; if (kprl.addr != htonl(INADDR_ANY) && prl->addr != kprl.addr) @@ -303,7 +310,7 @@ static int ipip6_tunnel_get_prl(struct ip_tunnel *t, break; } out: - read_unlock(&ipip6_lock); + rcu_read_unlock(); len = sizeof(*kp) * c; ret = 0; @@ -324,12 +331,14 @@ ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg) if (a->addr == htonl(INADDR_ANY)) return -EINVAL; - write_lock(&ipip6_lock); + spin_lock(&ipip6_prl_lock); for (p = t->prl; p; p = p->next) { if (p->addr == a->addr) { - if (chg) - goto update; + if (chg) { + p->flags = a->flags; + goto out; + } err = -EEXIST; goto out; } @@ -346,46 +355,63 @@ ipip6_tunnel_add_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a, int chg) goto out; } + INIT_RCU_HEAD(&p->rcu_head); p->next = t->prl; - t->prl = p; - t->prl_count++; -update: p->addr = a->addr; p->flags = a->flags; + t->prl_count++; + rcu_assign_pointer(t->prl, p); out: - write_unlock(&ipip6_lock); + spin_unlock(&ipip6_prl_lock); return err; } +static void prl_entry_destroy_rcu(struct rcu_head *head) +{ + kfree(container_of(head, struct ip_tunnel_prl_entry, rcu_head)); +} + +static void prl_list_destroy_rcu(struct rcu_head *head) +{ + struct ip_tunnel_prl_entry *p, *n; + + p = container_of(head, struct ip_tunnel_prl_entry, rcu_head); + do { + n = p->next; + kfree(p); + p = n; + } while (p); +} + static int ipip6_tunnel_del_prl(struct ip_tunnel *t, struct ip_tunnel_prl *a) { struct ip_tunnel_prl_entry *x, **p; int err = 0; - write_lock(&ipip6_lock); + spin_lock(&ipip6_prl_lock); if (a && a->addr != htonl(INADDR_ANY)) { for (p = &t->prl; *p; p = &(*p)->next) { if ((*p)->addr == a->addr) { x = *p; *p = x->next; - kfree(x); + call_rcu(&x->rcu_head, prl_entry_destroy_rcu); t->prl_count--; goto out; } } err = -ENXIO; } else { - while (t->prl) { + if (t->prl) { + t->prl_count = 0; x = t->prl; - t->prl = t->prl->next; - kfree(x); - t->prl_count--; + call_rcu(&x->rcu_head, prl_list_destroy_rcu); + t->prl = NULL; } } out: - write_unlock(&ipip6_lock); + spin_unlock(&ipip6_prl_lock); return err; } @@ -395,7 +421,7 @@ isatap_chksrc(struct sk_buff *skb, struct iphdr *iph, struct ip_tunnel *t) struct ip_tunnel_prl_entry *p; int ok = 1; - read_lock(&ipip6_lock); + rcu_read_lock(); p = __ipip6_tunnel_locate_prl(t, iph->saddr); if (p) { if (p->flags & PRL_DEFAULT) @@ -411,7 +437,7 @@ isatap_chksrc(struct sk_buff *skb, struct iphdr *iph, struct ip_tunnel *t) else ok = 0; } - read_unlock(&ipip6_lock); + rcu_read_unlock(); return ok; } @@ -1192,6 +1218,7 @@ static void __exit sit_cleanup(void) xfrm4_tunnel_deregister(&sit_handler, AF_INET6); unregister_pernet_gen_device(sit_net_id, &sit_net_ops); + rcu_barrier(); /* Wait for completion of call_rcu()'s */ } static int __init sit_init(void) -- 2.7.4