New version of the netlink_has_listeners() patch.
Changes:
- Fix missing listeners bitmap update when there was no delta in the
number of subscribed groups
- Use RCU to protect nltable listeners bitmap
[NETLINK]: Add netlink_has_listeners() for checking for multicast listeners
netlink_has_listeners() should be used to avoid unneccessary event message
generation if there are no listeners.
Signed-off-by: Patrick McHardy <[EMAIL PROTECTED]>
---
commit e32451ce5600d4e0d7f74486b840279986f05cfb
tree 19a1553d346d8877ffd95065f07a6b632338d6cc
parent 3ee68c4af3fd7228c1be63254b9f884614f9ebb2
author Patrick McHardy <[EMAIL PROTECTED]> Tue, 31 Jan 2006 01:20:38 +0100
committer Patrick McHardy <[EMAIL PROTECTED]> Tue, 31 Jan 2006 01:20:38 +0100
include/linux/netlink.h | 1
net/netlink/af_netlink.c | 100 ++++++++++++++++++++++++++++++++++++----------
2 files changed, 80 insertions(+), 21 deletions(-)
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 6a2ccf7..03ecb89 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -151,6 +151,7 @@ struct netlink_skb_parms
extern struct sock *netlink_kernel_create(int unit, unsigned int groups, void
(*input)(struct sock *sk, int len), struct module *module);
extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
+extern int netlink_has_listeners(struct sock *sk, unsigned int group);
extern int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 pid,
int nonblock);
extern int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 pid,
__u32 group, gfp_t allocation);
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 2101b45..bf963f6 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -106,6 +106,7 @@ struct nl_pid_hash {
struct netlink_table {
struct nl_pid_hash hash;
struct hlist_head mc_list;
+ unsigned long *listeners;
unsigned int nl_nonroot;
unsigned int groups;
struct module *module;
@@ -296,6 +297,38 @@ static inline int nl_pid_hash_dilute(str
static const struct proto_ops netlink_ops;
+static void
+netlink_update_listeners(struct netlink_table *tbl, struct sock *sk)
+{
+ struct netlink_sock *nlk = nlk_sk(sk);
+ struct hlist_node *node;
+ unsigned long mask;
+ unsigned int i;
+
+ for (i = 0; i < NLGRPSZ(tbl->groups)/sizeof(unsigned long); i++) {
+ mask = 0;
+ sk_for_each_bound(sk, node, &tbl->mc_list)
+ mask |= nlk->groups[i];
+ tbl->listeners[i] = mask;
+ }
+ /* make sure updates are visible before bind() or setsockopt() return */
+ smp_wmb();
+}
+
+static void
+netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
+{
+ struct netlink_table *tbl = &nl_table[sk->sk_protocol];
+ struct netlink_sock *nlk = nlk_sk(sk);
+
+ if (nlk->subscriptions && !subscriptions)
+ __sk_del_bind_node(sk);
+ else if (!nlk->subscriptions && subscriptions)
+ sk_add_bind_node(sk, &tbl->mc_list);
+ netlink_update_listeners(tbl, sk);
+ nlk->subscriptions = subscriptions;
+}
+
static int netlink_insert(struct sock *sk, u32 pid)
{
struct nl_pid_hash *hash = &nl_table[sk->sk_protocol].hash;
@@ -453,15 +486,27 @@ static int netlink_release(struct socket
notifier_call_chain(&netlink_chain, NETLINK_URELEASE, &n);
}
- if (nlk->module)
- module_put(nlk->module);
+ netlink_table_grab();
+ if (nlk->subscriptions) {
+ memset(nlk->groups, 0, NLGRPSZ(nlk->ngroups));
+ netlink_update_subscriptions(sk, 0);
+ }
if (nlk->flags & NETLINK_KERNEL_SOCKET) {
- netlink_table_grab();
+ unsigned long *listeners;
+
+ listeners = nl_table[sk->sk_protocol].listeners;
+ nl_table[sk->sk_protocol].listeners = NULL;
+ synchronize_rcu();
+ kfree(nl_table[sk->sk_protocol].listeners);
+
nl_table[sk->sk_protocol].module = NULL;
nl_table[sk->sk_protocol].registered = 0;
- netlink_table_ungrab();
}
+ netlink_table_ungrab();
+
+ if (nlk->module)
+ module_put(nlk->module);
kfree(nlk->groups);
nlk->groups = NULL;
@@ -514,18 +559,6 @@ static inline int netlink_capable(struct
capable(CAP_NET_ADMIN);
}
-static void
-netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
-{
- struct netlink_sock *nlk = nlk_sk(sk);
-
- if (nlk->subscriptions && !subscriptions)
- __sk_del_bind_node(sk);
- else if (!nlk->subscriptions && subscriptions)
- sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
- nlk->subscriptions = subscriptions;
-}
-
static int netlink_alloc_groups(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
@@ -554,6 +587,7 @@ static int netlink_bind(struct socket *s
struct sock *sk = sock->sk;
struct netlink_sock *nlk = nlk_sk(sk);
struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
+ unsigned int subscriptions;
int err;
if (nladdr->nl_family != AF_NETLINK)
@@ -585,10 +619,10 @@ static int netlink_bind(struct socket *s
return 0;
netlink_table_grab();
- netlink_update_subscriptions(sk, nlk->subscriptions +
- hweight32(nladdr->nl_groups) -
- hweight32(nlk->groups[0]));
- nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups;
+ subscriptions = nlk->subscriptions + hweight32(nladdr->nl_groups)
+ - hweight32(nlk->groups[0]);
+ nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups;
+ netlink_update_subscriptions(sk, subscriptions);
netlink_table_ungrab();
return 0;
@@ -806,6 +840,20 @@ retry:
return netlink_sendskb(sk, skb, ssk->sk_protocol);
}
+int netlink_has_listeners(struct sock *sk, unsigned int group)
+{
+ unsigned long *listeners;
+ int res = 0;
+
+ rcu_read_lock();
+ listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
+ if (group - 1 < nl_table[sk->sk_protocol].groups)
+ res = test_bit(group - 1, listeners);
+ rcu_read_unlock();
+ return res;
+}
+EXPORT_SYMBOL_GPL(netlink_has_listeners);
+
static __inline__ int netlink_broadcast_deliver(struct sock *sk, struct
sk_buff *skb)
{
struct netlink_sock *nlk = nlk_sk(sk);
@@ -1235,6 +1283,7 @@ netlink_kernel_create(int unit, unsigned
struct socket *sock;
struct sock *sk;
struct netlink_sock *nlk;
+ unsigned long *listeners = NULL;
if (!nl_table)
return NULL;
@@ -1248,6 +1297,13 @@ netlink_kernel_create(int unit, unsigned
if (__netlink_create(sock, unit) < 0)
goto out_sock_release;
+ if (groups < 32)
+ groups = 32;
+
+ listeners = kzalloc(NLGRPSZ(groups), GFP_KERNEL);
+ if (!listeners)
+ goto out_sock_release;
+
sk = sock->sk;
sk->sk_data_ready = netlink_data_ready;
if (input)
@@ -1260,7 +1316,8 @@ netlink_kernel_create(int unit, unsigned
nlk->flags |= NETLINK_KERNEL_SOCKET;
netlink_table_grab();
- nl_table[unit].groups = groups < 32 ? 32 : groups;
+ nl_table[unit].groups = groups;
+ nl_table[unit].listeners = listeners;
nl_table[unit].module = module;
nl_table[unit].registered = 1;
netlink_table_ungrab();
@@ -1268,6 +1325,7 @@ netlink_kernel_create(int unit, unsigned
return sk;
out_sock_release:
+ kfree(listeners);
sock_release(sock);
return NULL;
}
