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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@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-10-01 16:15:01 +00:00 committed by David S. Miller
parent 55747a0a73
commit 4c9687098f
1 changed files with 49 additions and 42 deletions
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91
net/ipv4/ipmr.c
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@ -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;
}
}
}