ipv6: Remove all uses of LL_ALLOCATED_SPACE

ipv6: Remove all uses of LL_ALLOCATED_SPACE

The macro LL_ALLOCATED_SPACE was ill-conceived.  It applies the
alignment to the sum of needed_headroom and needed_tailroom.  As
the amount that is then reserved for head room is needed_headroom
with alignment, this means that the tail room left may be too small.

This patch replaces all uses of LL_ALLOCATED_SPACE in net/ipv6
with the macro LL_RESERVED_SPACE and direct reference to
needed_tailroom.

This also fixes the problem with needed_headroom changing between
allocating the skb and reserving the head room.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 4 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index ee7839f4d6e3..7b94bebb73b1 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1343,13 +1343,15 @@ static struct sk_buff *mld_newpack(struct net_device *dev, int size)
         struct mld2_report *pmr;
         struct in6_addr addr_buf;
         const struct in6_addr *saddr;
+        int hlen = LL_RESERVED_SPACE(dev);
+        int tlen = dev->needed_tailroom;
         int err;
         u8 ra[8] = { IPPROTO_ICMPV6, 0,
                      IPV6_TLV_ROUTERALERT, 2, 0, 0,
                      IPV6_TLV_PADN, 0 };
 
         /* we assume size > sizeof(ra) here */
-        size += LL_ALLOCATED_SPACE(dev);
+        size += hlen + tlen;
         /* limit our allocations to order-0 page */
         size = min_t(int, size, SKB_MAX_ORDER(0, 0));
         skb = sock_alloc_send_skb(sk, size, 1, &err);
@@ -1357,7 +1359,7 @@ static struct sk_buff *mld_newpack(struct net_device *dev, int size)
         if (!skb)
                 return NULL;
 
-        skb_reserve(skb, LL_RESERVED_SPACE(dev));
+        skb_reserve(skb, hlen);
 
         if (ipv6_get_lladdr(dev, &addr_buf, IFA_F_TENTATIVE)) {
                 /* <draft-ietf-magma-mld-source-05.txt>:
@@ -1723,6 +1725,8 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type)
         struct mld_msg *hdr;
         const struct in6_addr *snd_addr, *saddr;
         struct in6_addr addr_buf;
+        int hlen = LL_RESERVED_SPACE(dev);
+        int tlen = dev->needed_tailroom;
         int err, len, payload_len, full_len;
         u8 ra[8] = { IPPROTO_ICMPV6, 0,
                      IPV6_TLV_ROUTERALERT, 2, 0, 0,
@@ -1744,7 +1748,7 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type)
                       IPSTATS_MIB_OUT, full_len);
         rcu_read_unlock();
 
-        skb = sock_alloc_send_skb(sk, LL_ALLOCATED_SPACE(dev) + full_len, 1, &err);
+        skb = sock_alloc_send_skb(sk, hlen + tlen + full_len, 1, &err);
 
         if (skb == NULL) {
                 rcu_read_lock();
@@ -1754,7 +1758,7 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type)
                 return;
         }
 
-        skb_reserve(skb, LL_RESERVED_SPACE(dev));
+        skb_reserve(skb, hlen);
 
         if (ipv6_get_lladdr(dev, &addr_buf, IFA_F_TENTATIVE)) {
                 /* <draft-ietf-magma-mld-source-05.txt>: