[INET]: Generalise tcp_tw_bucket, aka TIME_WAIT sockets

This paves the way to generalise the rest of the sock ID lookup
routines and saves some bytes in TCPv4 TIME_WAIT sockets on distro
kernels (where IPv6 is always built as a module):

[root@qemu ~]# grep tw_sock /proc/slabinfo
tw_sock_TCPv6  0  0  128  31  1
tw_sock_TCP    0  0   96  41  1
[root@qemu ~]#

Now if a protocol wants to use the TIME_WAIT generic infrastructure it
only has to set the sk_prot->twsk_obj_size field with the size of its
inet_timewait_sock derived sock and proto_register will create
sk_prot->twsk_slab, for now its only for INET sockets, but we can
introduce timewait_sock later if some non INET transport protocolo
wants to use this stuff.

Next changesets will take advantage of this new infrastructure to
generalise even more TCP code.

[acme@toy net-2.6.14]$ grep built-in /tmp/before.size /tmp/after.size
/tmp/before.size: 188646   11764    5068  205478   322a6 net/ipv4/built-in.o
/tmp/after.size:  188144   11764    5068  204976   320b0 net/ipv4/built-in.o
[acme@toy net-2.6.14]$

Tested with both IPv4 & IPv6 (::1 (localhost) & ::ffff:172.20.0.1
(qemu host)).

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 73 insertions, 69 deletions

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index f29e2f6ebe1b..5b5a49335fbb 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -41,7 +41,7 @@ int sysctl_tcp_max_tw_buckets = NR_FILE*2;
 int sysctl_tcp_syncookies = SYNC_INIT; 
 int sysctl_tcp_abort_on_overflow;
 
-static void tcp_tw_schedule(struct tcp_tw_bucket *tw, int timeo);
+static void tcp_tw_schedule(struct inet_timewait_sock *tw, int timeo);
 
 static __inline__ int tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win)
 {
@@ -58,7 +58,7 @@ int tcp_tw_count;
 
 
 /* Must be called with locally disabled BHs. */
-static void tcp_timewait_kill(struct tcp_tw_bucket *tw)
+static void tcp_timewait_kill(struct inet_timewait_sock *tw)
 {
         struct inet_bind_hashbucket *bhead;
         struct inet_bind_bucket *tb;
@@ -85,11 +85,11 @@ static void tcp_timewait_kill(struct tcp_tw_bucket *tw)
 
 #ifdef SOCK_REFCNT_DEBUG
         if (atomic_read(&tw->tw_refcnt) != 1) {
-                printk(KERN_DEBUG "tw_bucket %p refcnt=%d\n", tw,
-                       atomic_read(&tw->tw_refcnt));
+                printk(KERN_DEBUG "%s timewait_sock %p refcnt=%d\n",
+                       tw->tw_prot->name, tw, atomic_read(&tw->tw_refcnt));
         }
 #endif
-        tcp_tw_put(tw);
+        inet_twsk_put(tw);
 }
 
 /* 
@@ -121,19 +121,20 @@ static void tcp_timewait_kill(struct tcp_tw_bucket *tw)
  * to avoid misread sequence numbers, states etc.  --ANK
  */
 enum tcp_tw_status
-tcp_timewait_state_process(struct tcp_tw_bucket *tw, struct sk_buff *skb,
-                           struct tcphdr *th, unsigned len)
+tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
+                           const struct tcphdr *th)
 {
+        struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
         struct tcp_options_received tmp_opt;
         int paws_reject = 0;
 
         tmp_opt.saw_tstamp = 0;
-        if (th->doff > (sizeof(struct tcphdr) >> 2) && tw->tw_ts_recent_stamp) {
+        if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) {
                 tcp_parse_options(skb, &tmp_opt, 0);
 
                 if (tmp_opt.saw_tstamp) {
-                        tmp_opt.ts_recent          = tw->tw_ts_recent;
-                        tmp_opt.ts_recent_stamp = tw->tw_ts_recent_stamp;
+                        tmp_opt.ts_recent       = tcptw->tw_ts_recent;
+                        tmp_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
                         paws_reject = tcp_paws_check(&tmp_opt, th->rst);
                 }
         }
@@ -144,20 +145,20 @@ tcp_timewait_state_process(struct tcp_tw_bucket *tw, struct sk_buff *skb,
                 /* Out of window, send ACK */
                 if (paws_reject ||
                     !tcp_in_window(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq,
-                                   tw->tw_rcv_nxt,
-                                   tw->tw_rcv_nxt + tw->tw_rcv_wnd))
+                                   tcptw->tw_rcv_nxt,
+                                   tcptw->tw_rcv_nxt + tcptw->tw_rcv_wnd))
                         return TCP_TW_ACK;
 
                 if (th->rst)
                         goto kill;
 
-                if (th->syn && !before(TCP_SKB_CB(skb)->seq, tw->tw_rcv_nxt))
+                if (th->syn && !before(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt))
                         goto kill_with_rst;
 
                 /* Dup ACK? */
-                if (!after(TCP_SKB_CB(skb)->end_seq, tw->tw_rcv_nxt) ||
+                if (!after(TCP_SKB_CB(skb)->end_seq, tcptw->tw_rcv_nxt) ||
                     TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) {
-                        tcp_tw_put(tw);
+                        inet_twsk_put(tw);
                         return TCP_TW_SUCCESS;
                 }
 
@@ -165,19 +166,19 @@ tcp_timewait_state_process(struct tcp_tw_bucket *tw, struct sk_buff *skb,
                  * reset.
                  */
                 if (!th->fin ||
-                    TCP_SKB_CB(skb)->end_seq != tw->tw_rcv_nxt + 1) {
+                    TCP_SKB_CB(skb)->end_seq != tcptw->tw_rcv_nxt + 1) {
 kill_with_rst:
                         tcp_tw_deschedule(tw);
-                        tcp_tw_put(tw);
+                        inet_twsk_put(tw);
                         return TCP_TW_RST;
                 }
 
                 /* FIN arrived, enter true time-wait state. */
-                tw->tw_substate = TCP_TIME_WAIT;
-                tw->tw_rcv_nxt  = TCP_SKB_CB(skb)->end_seq;
+                tw->tw_substate   = TCP_TIME_WAIT;
+                tcptw->tw_rcv_nxt = TCP_SKB_CB(skb)->end_seq;
                 if (tmp_opt.saw_tstamp) {
-                        tw->tw_ts_recent_stamp  = xtime.tv_sec;
-                        tw->tw_ts_recent        = tmp_opt.rcv_tsval;
+                        tcptw->tw_ts_recent_stamp = xtime.tv_sec;
+                        tcptw->tw_ts_recent       = tmp_opt.rcv_tsval;
                 }
 
                 /* I am shamed, but failed to make it more elegant.
@@ -186,7 +187,7 @@ kill_with_rst:
                  * do not undertsnad recycling in any case, it not
                  * a big problem in practice. --ANK */
                 if (tw->tw_family == AF_INET &&
-                    sysctl_tcp_tw_recycle && tw->tw_ts_recent_stamp &&
+                    sysctl_tcp_tw_recycle && tcptw->tw_ts_recent_stamp &&
                     tcp_v4_tw_remember_stamp(tw))
                         tcp_tw_schedule(tw, tw->tw_timeout);
                 else
@@ -212,7 +213,7 @@ kill_with_rst:
          */
 
         if (!paws_reject &&
-            (TCP_SKB_CB(skb)->seq == tw->tw_rcv_nxt &&
+            (TCP_SKB_CB(skb)->seq == tcptw->tw_rcv_nxt &&
              (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq || th->rst))) {
                 /* In window segment, it may be only reset or bare ack. */
 
@@ -224,18 +225,18 @@ kill_with_rst:
                         if (sysctl_tcp_rfc1337 == 0) {
 kill:
                                 tcp_tw_deschedule(tw);
-                                tcp_tw_put(tw);
+                                inet_twsk_put(tw);
                                 return TCP_TW_SUCCESS;
                         }
                 }
                 tcp_tw_schedule(tw, TCP_TIMEWAIT_LEN);
 
                 if (tmp_opt.saw_tstamp) {
-                        tw->tw_ts_recent        = tmp_opt.rcv_tsval;
-                        tw->tw_ts_recent_stamp  = xtime.tv_sec;
+                        tcptw->tw_ts_recent       = tmp_opt.rcv_tsval;
+                        tcptw->tw_ts_recent_stamp = xtime.tv_sec;
                 }
 
-                tcp_tw_put(tw);
+                inet_twsk_put(tw);
                 return TCP_TW_SUCCESS;
         }
 
@@ -257,9 +258,10 @@ kill:
          */
 
         if (th->syn && !th->rst && !th->ack && !paws_reject &&
-            (after(TCP_SKB_CB(skb)->seq, tw->tw_rcv_nxt) ||
-             (tmp_opt.saw_tstamp && (s32)(tw->tw_ts_recent - tmp_opt.rcv_tsval) < 0))) {
-                u32 isn = tw->tw_snd_nxt + 65535 + 2;
+            (after(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt) ||
+             (tmp_opt.saw_tstamp &&
+              (s32)(tcptw->tw_ts_recent - tmp_opt.rcv_tsval) < 0))) {
+                u32 isn = tcptw->tw_snd_nxt + 65535 + 2;
                 if (isn == 0)
                         isn++;
                 TCP_SKB_CB(skb)->when = isn;
@@ -284,7 +286,7 @@ kill:
                  */
                 return TCP_TW_ACK;
         }
-        tcp_tw_put(tw);
+        inet_twsk_put(tw);
         return TCP_TW_SUCCESS;
 }
 
@@ -293,7 +295,7 @@ kill:
  * relevant info into it from the SK, and mess with hash chains
  * and list linkage.
  */
-static void __tcp_tw_hashdance(struct sock *sk, struct tcp_tw_bucket *tw)
+static void __tcp_tw_hashdance(struct sock *sk, struct inet_timewait_sock *tw)
 {
         const struct inet_sock *inet = inet_sk(sk);
         struct inet_ehash_bucket *ehead = &tcp_hashinfo.ehash[sk->sk_hashent];
@@ -306,7 +308,7 @@ static void __tcp_tw_hashdance(struct sock *sk, struct tcp_tw_bucket *tw)
         spin_lock(&bhead->lock);
         tw->tw_tb = inet->bind_hash;
         BUG_TRAP(inet->bind_hash);
-        tw_add_bind_node(tw, &tw->tw_tb->owners);
+        inet_twsk_add_bind_node(tw, &tw->tw_tb->owners);
         spin_unlock(&bhead->lock);
 
         write_lock(&ehead->lock);
@@ -316,7 +318,7 @@ static void __tcp_tw_hashdance(struct sock *sk, struct tcp_tw_bucket *tw)
                 sock_prot_dec_use(sk->sk_prot);
 
         /* Step 3: Hash TW into TIMEWAIT half of established hash table. */
-        tw_add_node(tw, &(ehead + tcp_hashinfo.ehash_size)->chain);
+        inet_twsk_add_node(tw, &(ehead + tcp_hashinfo.ehash_size)->chain);
         atomic_inc(&tw->tw_refcnt);
 
         write_unlock(&ehead->lock);
@@ -327,19 +329,23 @@ static void __tcp_tw_hashdance(struct sock *sk, struct tcp_tw_bucket *tw)
  */ 
 void tcp_time_wait(struct sock *sk, int state, int timeo)
 {
-        struct tcp_tw_bucket *tw = NULL;
-        struct tcp_sock *tp = tcp_sk(sk);
+        struct inet_timewait_sock *tw = NULL;
+        const struct tcp_sock *tp = tcp_sk(sk);
         int recycle_ok = 0;
 
         if (sysctl_tcp_tw_recycle && tp->rx_opt.ts_recent_stamp)
                 recycle_ok = tp->af_specific->remember_stamp(sk);
 
         if (tcp_tw_count < sysctl_tcp_max_tw_buckets)
-                tw = kmem_cache_alloc(tcp_timewait_cachep, SLAB_ATOMIC);
+                tw = kmem_cache_alloc(sk->sk_prot_creator->twsk_slab, SLAB_ATOMIC);
+
+        if (tw != NULL) {
+                struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
+                const struct inet_sock *inet = inet_sk(sk);
+                const int rto = (tp->rto << 2) - (tp->rto >> 1);
 
-        if(tw != NULL) {
-                struct inet_sock *inet = inet_sk(sk);
-                int rto = (tp->rto<<2) - (tp->rto>>1);
+                /* Remember our protocol */
+                tw->tw_prot             = sk->sk_prot_creator;
 
                 /* Give us an identity. */
                 tw->tw_daddr            = inet->daddr;
@@ -356,25 +362,23 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
                 atomic_set(&tw->tw_refcnt, 1);
 
                 tw->tw_hashent          = sk->sk_hashent;
-                tw->tw_rcv_nxt          = tp->rcv_nxt;
-                tw->tw_snd_nxt          = tp->snd_nxt;
-                tw->tw_rcv_wnd          = tcp_receive_window(tp);
-                tw->tw_ts_recent        = tp->rx_opt.ts_recent;
-                tw->tw_ts_recent_stamp  = tp->rx_opt.ts_recent_stamp;
-                tw_dead_node_init(tw);
+                tcptw->tw_rcv_nxt       = tp->rcv_nxt;
+                tcptw->tw_snd_nxt       = tp->snd_nxt;
+                tcptw->tw_rcv_wnd       = tcp_receive_window(tp);
+                tcptw->tw_ts_recent     = tp->rx_opt.ts_recent;
+                tcptw->tw_ts_recent_stamp = tp->rx_opt.ts_recent_stamp;
+                inet_twsk_dead_node_init(tw);
 
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
                 if (tw->tw_family == PF_INET6) {
                         struct ipv6_pinfo *np = inet6_sk(sk);
+                        struct tcp6_timewait_sock *tcp6tw = tcp6_twsk((struct sock *)tw);
 
-                        ipv6_addr_copy(&tw->tw_v6_daddr, &np->daddr);
-                        ipv6_addr_copy(&tw->tw_v6_rcv_saddr, &np->rcv_saddr);
-                        tw->tw_v6_ipv6only = np->ipv6only;
-                } else {
-                        memset(&tw->tw_v6_daddr, 0, sizeof(tw->tw_v6_daddr));
-                        memset(&tw->tw_v6_rcv_saddr, 0, sizeof(tw->tw_v6_rcv_saddr));
-                        tw->tw_v6_ipv6only = 0;
-                }
+                        ipv6_addr_copy(&tcp6tw->tw_v6_daddr, &np->daddr);
+                        ipv6_addr_copy(&tcp6tw->tw_v6_rcv_saddr, &np->rcv_saddr);
+                        tw->tw_ipv6only = np->ipv6only;
+                } else
+                        tw->tw_ipv6only = 0;
 #endif
                 /* Linkage updates. */
                 __tcp_tw_hashdance(sk, tw);
@@ -392,7 +396,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
                 }
 
                 tcp_tw_schedule(tw, timeo);
-                tcp_tw_put(tw);
+                inet_twsk_put(tw);
         } else {
                 /* Sorry, if we're out of memory, just CLOSE this
                  * socket up.  We've got bigger problems than
@@ -427,7 +431,7 @@ static u32 twkill_thread_slots;
 /* Returns non-zero if quota exceeded.  */
 static int tcp_do_twkill_work(int slot, unsigned int quota)
 {
-        struct tcp_tw_bucket *tw;
+        struct inet_timewait_sock *tw;
         struct hlist_node *node;
         unsigned int killed;
         int ret;
@@ -441,11 +445,11 @@ static int tcp_do_twkill_work(int slot, unsigned int quota)
         killed = 0;
         ret = 0;
 rescan:
-        tw_for_each_inmate(tw, node, &tcp_tw_death_row[slot]) {
-                __tw_del_dead_node(tw);
+        inet_twsk_for_each_inmate(tw, node, &tcp_tw_death_row[slot]) {
+                __inet_twsk_del_dead_node(tw);
                 spin_unlock(&tw_death_lock);
                 tcp_timewait_kill(tw);
-                tcp_tw_put(tw);
+                inet_twsk_put(tw);
                 killed++;
                 spin_lock(&tw_death_lock);
                 if (killed > quota) {
@@ -531,11 +535,11 @@ static void twkill_work(void *dummy)
  */
 
 /* This is for handling early-kills of TIME_WAIT sockets. */
-void tcp_tw_deschedule(struct tcp_tw_bucket *tw)
+void tcp_tw_deschedule(struct inet_timewait_sock *tw)
 {
         spin_lock(&tw_death_lock);
-        if (tw_del_dead_node(tw)) {
-                tcp_tw_put(tw);
+        if (inet_twsk_del_dead_node(tw)) {
+                inet_twsk_put(tw);
                 if (--tcp_tw_count == 0)
                         del_timer(&tcp_tw_timer);
         }
@@ -552,7 +556,7 @@ static struct timer_list tcp_twcal_timer =
                 TIMER_INITIALIZER(tcp_twcal_tick, 0, 0);
 static struct hlist_head tcp_twcal_row[TCP_TW_RECYCLE_SLOTS];
 
-static void tcp_tw_schedule(struct tcp_tw_bucket *tw, int timeo)
+static void tcp_tw_schedule(struct inet_timewait_sock *tw, const int timeo)
 {
         struct hlist_head *list;
         int slot;
@@ -586,7 +590,7 @@ static void tcp_tw_schedule(struct tcp_tw_bucket *tw, int timeo)
         spin_lock(&tw_death_lock);
 
         /* Unlink it, if it was scheduled */
-        if (tw_del_dead_node(tw))
+        if (inet_twsk_del_dead_node(tw))
                 tcp_tw_count--;
         else
                 atomic_inc(&tw->tw_refcnt);
@@ -644,13 +648,13 @@ void tcp_twcal_tick(unsigned long dummy)
         for (n=0; n<TCP_TW_RECYCLE_SLOTS; n++) {
                 if (time_before_eq(j, now)) {
                         struct hlist_node *node, *safe;
-                        struct tcp_tw_bucket *tw;
+                        struct inet_timewait_sock *tw;
 
-                        tw_for_each_inmate_safe(tw, node, safe,
-                                           &tcp_twcal_row[slot]) {
-                                __tw_del_dead_node(tw);
+                        inet_twsk_for_each_inmate_safe(tw, node, safe,
+                                                       &tcp_twcal_row[slot]) {
+                                __inet_twsk_del_dead_node(tw);
                                 tcp_timewait_kill(tw);
-                                tcp_tw_put(tw);
+                                inet_twsk_put(tw);
                                 killed++;
                         }
                 } else {