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Date: Mon, 22 Nov 2010 18:36:17 +0000
From: Alban Crequy <alban.crequy@...labora.co.uk>
To: Alban Crequy <alban.crequy@...labora.co.uk>
Cc: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <eric.dumazet@...il.com>,
Stephen Hemminger <shemminger@...tta.com>,
Cyrill Gorcunov <gorcunov@...nvz.org>,
Alexey Dobriyan <adobriyan@...il.com>,
Lennart Poettering <lennart@...ttering.net>,
Kay Sievers <kay.sievers@...y.org>,
Ian Molton <ian.molton@...labora.co.uk>,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
Alban Crequy <alban.crequy@...labora.co.uk>
Subject: [PATCH 4/9] AF_UNIX: find the recipients for multicast messages
unix_find_multicast_recipients() builds an array of recipients. It can either
find the peers of a specific multicast address, or find all the peers of all
multicast group the sender is part of.
Signed-off-by: Alban Crequy <alban.crequy@...labora.co.uk>
---
net/unix/af_unix.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 144 insertions(+), 0 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 2278829..3cc9695 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -114,15 +114,48 @@
#include <linux/mount.h>
#include <net/checksum.h>
#include <linux/security.h>
+#include <linux/sort.h>
static struct hlist_head unix_socket_table[UNIX_HASH_SIZE + 1];
static DEFINE_SPINLOCK(unix_table_lock);
+static DEFINE_SPINLOCK(unix_multicast_lock);
static atomic_long_t unix_nr_socks;
#define unix_sockets_unbound (&unix_socket_table[UNIX_HASH_SIZE])
#define UNIX_ABSTRACT(sk) (unix_sk(sk)->addr->hash != UNIX_HASH_SIZE)
+struct sock_item {
+ struct sock *s;
+ struct sk_buff *skb;
+ int to_deliver;
+};
+
+struct sock_set {
+ int cnt;
+ struct sock_item items[0];
+};
+
+static void kfree_sock_set(struct sock_set *set)
+{
+ int i;
+ for (i = 0 ; i < set->cnt ; i++)
+ sock_put(set->items[i].s);
+ kfree(set);
+}
+
+static int sock_item_compare(const void *_a, const void *_b)
+{
+ const struct sock_item *a = _a;
+ const struct sock_item *b = _b;
+ if (a->s > b->s)
+ return 1;
+ else if (a->s < b->s)
+ return -1;
+ else
+ return 0;
+}
+
#ifdef CONFIG_SECURITY_NETWORK
static void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
{
@@ -824,6 +857,117 @@ fail:
return NULL;
}
+static int unix_find_multicast_members(struct sock_set *set,
+ int recipient_cnt,
+ struct sock *sender,
+ struct hlist_head *list)
+{
+ struct unix_mcast *node;
+ struct hlist_node *pos;
+ hlist_for_each_entry(node, pos, list,
+ member_node) {
+ if (set->cnt + 1 > recipient_cnt)
+ return -ENOMEM;
+ if (node->member == unix_sk(sender) &&
+ !(node->flags & UNIX_MREQ_LOOPBACK))
+ continue;
+
+ sock_hold(&node->member->sk);
+ set->items[set->cnt].s = &node->member->sk;
+ set->items[set->cnt].skb = NULL;
+ set->items[set->cnt].to_deliver = 1;
+ set->cnt++;
+ }
+ return 0;
+}
+
+/* Find the recipients for a message sent by 'sender' to 'addr'. If 'dest' is
+ * NULL, the recipients are peers of all subscribed groups.
+ */
+static struct sock_set *unix_find_multicast_recipients(struct sock *sender,
+ struct sock *dest,
+ int *err)
+{
+ struct unix_sock *u = unix_sk(sender);
+ struct unix_mcast *node;
+ struct hlist_node *pos;
+ struct sock_set *set;
+ int recipient_cnt;
+
+ /* We cannot allocate in the spin lock. First, count the recipients */
+try_again:
+ spin_lock(&unix_multicast_lock);
+ if (dest != NULL) {
+ if (unix_sk(dest)->is_mcast_addr) {
+ recipient_cnt = unix_sk(dest)->mcast_members_cnt;
+ } else {
+ recipient_cnt = 1;
+ }
+ } else {
+ recipient_cnt = 0;
+ hlist_for_each_entry(node, pos, &u->mcast_subscriptions,
+ subscription_node) {
+ recipient_cnt += node->addr->mcast_members_cnt;
+ }
+ }
+ spin_unlock(&unix_multicast_lock);
+
+ /* Allocate for the set and hope the number of recipients does not
+ * change while the lock is released. If it changes, we have to try
+ * again... We allocate a bit more than needed, so if a _few_ members
+ * are added in a multicast group meanwhile, we don't always need to
+ * try again. */
+ recipient_cnt += 5;
+
+ set = kmalloc(sizeof(struct sock_set)
+ + sizeof(struct sock_item) * recipient_cnt,
+ GFP_KERNEL);
+ if (!set) {
+ *err = -ENOMEM;
+ return NULL;
+ }
+ set->cnt = 0;
+
+ spin_lock(&unix_multicast_lock);
+ if (dest && unix_sk(dest)->is_mcast_addr) {
+ /* Message sent to a multicast address */
+ if (unix_find_multicast_members(set, recipient_cnt,
+ sender,
+ &unix_sk(dest)->mcast_members)) {
+ spin_unlock(&unix_multicast_lock);
+ kfree_sock_set(set);
+ goto try_again;
+ }
+ } else if (!dest) {
+ /* Destination not specified, sending to all peers of
+ * subscribed groups */
+ hlist_for_each_entry(node, pos, &u->mcast_subscriptions,
+ subscription_node) {
+ if (unix_find_multicast_members(set, recipient_cnt,
+ sender,
+ &node->addr->mcast_members)) {
+ spin_unlock(&unix_multicast_lock);
+ kfree_sock_set(set);
+ goto try_again;
+ }
+ }
+ } else {
+ /* Message sent to a non-multicast address */
+ BUG_ON(recipient_cnt < 1);
+ set->cnt = 1;
+ sock_hold(dest);
+ set->items[0].s = dest;
+ set->items[0].skb = NULL;
+ set->items[0].to_deliver = 1;
+ }
+ spin_unlock(&unix_multicast_lock);
+
+ /* Keep the array ordered to prevent deadlocks on circular waits */
+ sort(set->items, set->cnt, sizeof(struct sock_item),
+ sock_item_compare, NULL);
+ return set;
+}
+
static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
--
1.7.1
--
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