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Message-ID: <1285985701.2582.522.camel@edumazet-laptop>
Date: Sat, 02 Oct 2010 04:15:01 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next 2/4] ipmr: RCU conversion of mroute_sk
Use RCU and RTNL to protect (struct mr_table)->mroute_sk
Readers use RCU, writers use RTNL.
ip_ra_control() already use an RCU grace period before
ip_ra_destroy_rcu(), so we dont need synchronize_rcu() in
mrtsock_destruct()
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
net/ipv4/ipmr.c | 91
++++++++++++++++++++++++++++++--------------------------
1 file changed, 49 insertions(+), 42 deletions(-)
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 1a92ebd..e2db2ea 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -75,7 +75,7 @@ struct mr_table {
struct net *net;
#endif
u32 id;
- struct sock *mroute_sk;
+ struct sock __rcu *mroute_sk;
struct timer_list ipmr_expire_timer;
struct list_head mfc_unres_queue;
struct list_head mfc_cache_array[MFC_LINES];
@@ -867,6 +867,7 @@ static int ipmr_cache_report(struct mr_table *mrt,
const int ihl = ip_hdrlen(pkt);
struct igmphdr *igmp;
struct igmpmsg *msg;
+ struct sock *mroute_sk;
int ret;
#ifdef CONFIG_IP_PIMSM
@@ -925,7 +926,10 @@ static int ipmr_cache_report(struct mr_table *mrt,
skb->transport_header = skb->network_header;
}
- if (mrt->mroute_sk == NULL) {
+ rcu_read_lock();
+ mroute_sk = rcu_dereference(mrt->mroute_sk);
+ if (mroute_sk == NULL) {
+ rcu_read_unlock();
kfree_skb(skb);
return -EINVAL;
}
@@ -933,7 +937,8 @@ static int ipmr_cache_report(struct mr_table *mrt,
/*
* Deliver to mrouted
*/
- ret = sock_queue_rcv_skb(mrt->mroute_sk, skb);
+ ret = sock_queue_rcv_skb(mroute_sk, skb);
+ rcu_read_unlock();
if (ret < 0) {
if (net_ratelimit())
printk(KERN_WARNING "mroute: pending queue full, dropping entries.\n");
@@ -1164,6 +1169,9 @@ static void mroute_clean_tables(struct mr_table *mrt)
}
}
+/* called from ip_ra_control(), before an RCU grace period,
+ * we dont need to call synchronize_rcu() here
+ */
static void mrtsock_destruct(struct sock *sk)
{
struct net *net = sock_net(sk);
@@ -1171,13 +1179,9 @@ static void mrtsock_destruct(struct sock *sk)
rtnl_lock();
ipmr_for_each_table(mrt, net) {
- if (sk == mrt->mroute_sk) {
+ if (sk == rtnl_dereference(mrt->mroute_sk)) {
IPV4_DEVCONF_ALL(net, MC_FORWARDING)--;
-
- write_lock_bh(&mrt_lock);
- mrt->mroute_sk = NULL;
- write_unlock_bh(&mrt_lock);
-
+ rcu_assign_pointer(mrt->mroute_sk, NULL);
mroute_clean_tables(mrt);
}
}
@@ -1204,7 +1208,8 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi
return -ENOENT;
if (optname != MRT_INIT) {
- if (sk != mrt->mroute_sk && !capable(CAP_NET_ADMIN))
+ if (sk != rcu_dereference_raw(mrt->mroute_sk) &&
+ !capable(CAP_NET_ADMIN))
return -EACCES;
}
@@ -1217,23 +1222,20 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi
return -ENOPROTOOPT;
rtnl_lock();
- if (mrt->mroute_sk) {
+ if (rtnl_dereference(mrt->mroute_sk)) {
rtnl_unlock();
return -EADDRINUSE;
}
ret = ip_ra_control(sk, 1, mrtsock_destruct);
if (ret == 0) {
- write_lock_bh(&mrt_lock);
- mrt->mroute_sk = sk;
- write_unlock_bh(&mrt_lock);
-
+ rcu_assign_pointer(mrt->mroute_sk, sk);
IPV4_DEVCONF_ALL(net, MC_FORWARDING)++;
}
rtnl_unlock();
return ret;
case MRT_DONE:
- if (sk != mrt->mroute_sk)
+ if (sk != rcu_dereference_raw(mrt->mroute_sk))
return -EACCES;
return ip_ra_control(sk, 0, NULL);
case MRT_ADD_VIF:
@@ -1246,7 +1248,8 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi
return -ENFILE;
rtnl_lock();
if (optname == MRT_ADD_VIF) {
- ret = vif_add(net, mrt, &vif, sk == mrt->mroute_sk);
+ ret = vif_add(net, mrt, &vif,
+ sk == rtnl_dereference(mrt->mroute_sk));
} else {
ret = vif_delete(mrt, vif.vifc_vifi, 0, NULL);
}
@@ -1267,7 +1270,8 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi
if (optname == MRT_DEL_MFC)
ret = ipmr_mfc_delete(mrt, &mfc);
else
- ret = ipmr_mfc_add(net, mrt, &mfc, sk == mrt->mroute_sk);
+ ret = ipmr_mfc_add(net, mrt, &mfc,
+ sk == rtnl_dereference(mrt->mroute_sk));
rtnl_unlock();
return ret;
/*
@@ -1309,14 +1313,16 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi
return -EINVAL;
if (get_user(v, (u32 __user *)optval))
return -EFAULT;
- if (sk == mrt->mroute_sk)
- return -EBUSY;
rtnl_lock();
ret = 0;
- if (!ipmr_new_table(net, v))
- ret = -ENOMEM;
- raw_sk(sk)->ipmr_table = v;
+ if (sk == rtnl_dereference(mrt->mroute_sk)) {
+ ret = -EBUSY;
+ } else {
+ if (!ipmr_new_table(net, v))
+ ret = -ENOMEM;
+ raw_sk(sk)->ipmr_table = v;
+ }
rtnl_unlock();
return ret;
}
@@ -1713,6 +1719,7 @@ dont_forward:
/*
* Multicast packets for forwarding arrive here
+ * Called with rcu_read_lock();
*/
int ip_mr_input(struct sk_buff *skb)
@@ -1726,7 +1733,7 @@ int ip_mr_input(struct sk_buff *skb)
/* Packet is looped back after forward, it should not be
forwarded second time, but still can be delivered locally.
*/
- if (IPCB(skb)->flags&IPSKB_FORWARDED)
+ if (IPCB(skb)->flags & IPSKB_FORWARDED)
goto dont_forward;
err = ipmr_fib_lookup(net, &skb_rtable(skb)->fl, &mrt);
@@ -1736,24 +1743,24 @@ int ip_mr_input(struct sk_buff *skb)
}
if (!local) {
- if (IPCB(skb)->opt.router_alert) {
- if (ip_call_ra_chain(skb))
- return 0;
- } else if (ip_hdr(skb)->protocol == IPPROTO_IGMP){
- /* IGMPv1 (and broken IGMPv2 implementations sort of
- Cisco IOS <= 11.2(8)) do not put router alert
- option to IGMP packets destined to routable
- groups. It is very bad, because it means
- that we can forward NO IGMP messages.
- */
- read_lock(&mrt_lock);
- if (mrt->mroute_sk) {
- nf_reset(skb);
- raw_rcv(mrt->mroute_sk, skb);
- read_unlock(&mrt_lock);
- return 0;
- }
- read_unlock(&mrt_lock);
+ if (IPCB(skb)->opt.router_alert) {
+ if (ip_call_ra_chain(skb))
+ return 0;
+ } else if (ip_hdr(skb)->protocol == IPPROTO_IGMP) {
+ /* IGMPv1 (and broken IGMPv2 implementations sort of
+ * Cisco IOS <= 11.2(8)) do not put router alert
+ * option to IGMP packets destined to routable
+ * groups. It is very bad, because it means
+ * that we can forward NO IGMP messages.
+ */
+ struct sock *mroute_sk;
+
+ mroute_sk = rcu_dereference(mrt->mroute_sk);
+ if (mroute_sk) {
+ nf_reset(skb);
+ raw_rcv(mroute_sk, skb);
+ return 0;
+ }
}
}
--
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