ipv6: refactor ipv6_dev_mc_inc()

Refactor out allocation and initialization and make
the refcount code more readable.

Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 49 insertions, 33 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index d64e26366cb8..592eba61e78a 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -641,14 +641,6 @@ bool inet6_mc_check(struct sock *sk, const struct in6_addr *mc_addr,
         return rv;
 }
 
-static void ma_put(struct ifmcaddr6 *mc)
-{
-        if (atomic_dec_and_test(&mc->mca_refcnt)) {
-                in6_dev_put(mc->idev);
-                kfree(mc);
-        }
-}
-
 static void igmp6_group_added(struct ifmcaddr6 *mc)
 {
         struct net_device *dev = mc->idev->dev;
@@ -814,6 +806,48 @@ static void mld_clear_delrec(struct inet6_dev *idev)
         read_unlock_bh(&idev->lock);
 }
 
+static void mca_get(struct ifmcaddr6 *mc)
+{
+        atomic_inc(&mc->mca_refcnt);
+}
+
+static void ma_put(struct ifmcaddr6 *mc)
+{
+        if (atomic_dec_and_test(&mc->mca_refcnt)) {
+                in6_dev_put(mc->idev);
+                kfree(mc);
+        }
+}
+
+static struct ifmcaddr6 *mca_alloc(struct inet6_dev *idev,
+                                   const struct in6_addr *addr)
+{
+        struct ifmcaddr6 *mc;
+
+        mc = kzalloc(sizeof(*mc), GFP_ATOMIC);
+        if (mc == NULL)
+                return NULL;
+
+        setup_timer(&mc->mca_timer, igmp6_timer_handler, (unsigned long)mc);
+
+        mc->mca_addr = *addr;
+        mc->idev = idev; /* reference taken by caller */
+        mc->mca_users = 1;
+        /* mca_stamp should be updated upon changes */
+        mc->mca_cstamp = mc->mca_tstamp = jiffies;
+        atomic_set(&mc->mca_refcnt, 1);
+        spin_lock_init(&mc->mca_lock);
+
+        /* initial mode is (EX, empty) */
+        mc->mca_sfmode = MCAST_EXCLUDE;
+        mc->mca_sfcount[MCAST_EXCLUDE] = 1;
+
+        if (ipv6_addr_is_ll_all_nodes(&mc->mca_addr) ||
+            IPV6_ADDR_MC_SCOPE(&mc->mca_addr) < IPV6_ADDR_SCOPE_LINKLOCAL)
+                mc->mca_flags |= MAF_NOREPORT;
+
+        return mc;
+}
 
 /*
  *      device multicast group inc (add if not found)
@@ -849,38 +883,20 @@ int ipv6_dev_mc_inc(struct net_device *dev, const struct in6_addr *addr)
                 }
         }
 
-        /*
-         *      not found: create a new one.
-         */
-
-        mc = kzalloc(sizeof(struct ifmcaddr6), GFP_ATOMIC);
-
-        if (mc == NULL) {
+        mc = mca_alloc(idev, addr);
+        if (!mc) {
                 write_unlock_bh(&idev->lock);
                 in6_dev_put(idev);
                 return -ENOMEM;
         }
 
-        setup_timer(&mc->mca_timer, igmp6_timer_handler, (unsigned long)mc);
-
-        mc->mca_addr = *addr;
-        mc->idev = idev; /* (reference taken) */
-        mc->mca_users = 1;
-        /* mca_stamp should be updated upon changes */
-        mc->mca_cstamp = mc->mca_tstamp = jiffies;
-        atomic_set(&mc->mca_refcnt, 2);
-        spin_lock_init(&mc->mca_lock);
-
-        /* initial mode is (EX, empty) */
-        mc->mca_sfmode = MCAST_EXCLUDE;
-        mc->mca_sfcount[MCAST_EXCLUDE] = 1;
-
-        if (ipv6_addr_is_ll_all_nodes(&mc->mca_addr) ||
-            IPV6_ADDR_MC_SCOPE(&mc->mca_addr) < IPV6_ADDR_SCOPE_LINKLOCAL)
-                mc->mca_flags |= MAF_NOREPORT;
-
         mc->next = idev->mc_list;
         idev->mc_list = mc;
+
+        /* Hold this for the code below before we unlock,
+         * it is already exposed via idev->mc_list.
+         */
+        mca_get(mc);
         write_unlock_bh(&idev->lock);
 
         mld_del_delrec(idev, &mc->mca_addr);