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Message-ID: <4AE279BE.30600@gmail.com>
Date: Sat, 24 Oct 2009 05:51:26 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: "David S. Miller" <davem@...emloft.net>
CC: Linux Netdev List <netdev@...r.kernel.org>,
Yoshifuji Hideaki <yoshfuji@...ux-ipv6.org>
Subject: [PATCH 1/2 net-next-2.6] 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 <eric.dumazet@...il.com>
---
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..290effb 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..8cdcc2a 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)
--
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