inetpeer: restore small inet_peer structures

Addition of rcu_head to struct inet_peer added 16bytes on 64bit arches.

Thats a bit unfortunate, since old size was exactly 64 bytes.

This can be solved, using an union between this rcu_head an four fields,
that are normally used only when a refcount is taken on inet_peer.
rcu_head is used only when refcnt=-1, right before structure freeing.

Add a inet_peer_refcheck() function to check this assertion for a while.

We can bring back SLAB_HWCACHE_ALIGN qualifier in kmem cache creation.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 4 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 7f9515c0379f..2e41e6f92968 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -204,10 +204,12 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
                  * TIME-WAIT * and initialize rx_opt.ts_recent from it,
                  * when trying new connection.
                  */
-                if (peer != NULL &&
-                    (u32)get_seconds() - peer->tcp_ts_stamp <= TCP_PAWS_MSL) {
-                        tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
-                        tp->rx_opt.ts_recent = peer->tcp_ts;
+                if (peer) {
+                        inet_peer_refcheck(peer);
+                        if ((u32)get_seconds() - peer->tcp_ts_stamp <= TCP_PAWS_MSL) {
+                                tp->rx_opt.ts_recent_stamp = peer->tcp_ts_stamp;
+                                tp->rx_opt.ts_recent = peer->tcp_ts;
+                        }
                 }
         }
 
@@ -1351,6 +1353,7 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
                     (dst = inet_csk_route_req(sk, req)) != NULL &&
                     (peer = rt_get_peer((struct rtable *)dst)) != NULL &&
                     peer->v4daddr == saddr) {
+                        inet_peer_refcheck(peer);
                         if ((u32)get_seconds() - peer->tcp_ts_stamp < TCP_PAWS_MSL &&
                             (s32)(peer->tcp_ts - req->ts_recent) >
                                                         TCP_PAWS_WINDOW) {