tcp: de-bloat a bit with factoring NET_INC_STATS_BH out

There are some places in TCP that select one MIB index to
bump snmp statistics like this:

	if (<something>)
		NET_INC_STATS_BH(<some_id>);
	else if (<something_else>)
		NET_INC_STATS_BH(<some_other_id>);
	...
	else
		NET_INC_STATS_BH(<default_id>);

or in a more tricky but still similar way.

On the other hand, this NET_INC_STATS_BH is a camouflaged
increment of percpu variable, which is not that small.

Factoring those cases out de-bloats 235 bytes on non-preemptible
i386 config and drives parts of the code into 80 columns.

add/remove: 0/0 grow/shrink: 0/7 up/down: 0/-235 (-235)
function                                     old     new   delta
tcp_fastretrans_alert                       1437    1424     -13
tcp_dsack_set                                137     124     -13
tcp_xmit_retransmit_queue                    690     676     -14
tcp_try_undo_recovery                        283     265     -18
tcp_sacktag_write_queue                     1550    1515     -35
tcp_update_reordering                        162     106     -56
tcp_retransmit_timer                         990     904     -86

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 46 insertions, 22 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index de30e70ff256..d6ea970a1513 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -947,17 +947,21 @@ static void tcp_update_reordering(struct sock *sk, const int metric,
 {
         struct tcp_sock *tp = tcp_sk(sk);
         if (metric > tp->reordering) {
+                int mib_idx;
+
                 tp->reordering = min(TCP_MAX_REORDERING, metric);
 
                 /* This exciting event is worth to be remembered. 8) */
                 if (ts)
-                        NET_INC_STATS_BH(LINUX_MIB_TCPTSREORDER);
+                        mib_idx = LINUX_MIB_TCPTSREORDER;
                 else if (tcp_is_reno(tp))
-                        NET_INC_STATS_BH(LINUX_MIB_TCPRENOREORDER);
+                        mib_idx = LINUX_MIB_TCPRENOREORDER;
                 else if (tcp_is_fack(tp))
-                        NET_INC_STATS_BH(LINUX_MIB_TCPFACKREORDER);
+                        mib_idx = LINUX_MIB_TCPFACKREORDER;
                 else
-                        NET_INC_STATS_BH(LINUX_MIB_TCPSACKREORDER);
+                        mib_idx = LINUX_MIB_TCPSACKREORDER;
+
+                NET_INC_STATS_BH(mib_idx);
 #if FASTRETRANS_DEBUG > 1
                 printk(KERN_DEBUG "Disorder%d %d %u f%u s%u rr%d\n",
                        tp->rx_opt.sack_ok, inet_csk(sk)->icsk_ca_state,
@@ -1456,18 +1460,22 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb,
                 if (!tcp_is_sackblock_valid(tp, dup_sack,
                                             sp[used_sacks].start_seq,
                                             sp[used_sacks].end_seq)) {
+                        int mib_idx;
+
                         if (dup_sack) {
                                 if (!tp->undo_marker)
-                                        NET_INC_STATS_BH(LINUX_MIB_TCPDSACKIGNOREDNOUNDO);
+                                        mib_idx = LINUX_MIB_TCPDSACKIGNOREDNOUNDO;
                                 else
-                                        NET_INC_STATS_BH(LINUX_MIB_TCPDSACKIGNOREDOLD);
+                                        mib_idx = LINUX_MIB_TCPDSACKIGNOREDOLD;
                         } else {
                                 /* Don't count olds caused by ACK reordering */
                                 if ((TCP_SKB_CB(ack_skb)->ack_seq != tp->snd_una) &&
                                     !after(sp[used_sacks].end_seq, tp->snd_una))
                                         continue;
-                                NET_INC_STATS_BH(LINUX_MIB_TCPSACKDISCARD);
+                                mib_idx = LINUX_MIB_TCPSACKDISCARD;
                         }
+
+                        NET_INC_STATS_BH(mib_idx);
                         if (i == 0)
                                 first_sack_index = -1;
                         continue;
@@ -2380,15 +2388,19 @@ static int tcp_try_undo_recovery(struct sock *sk)
         struct tcp_sock *tp = tcp_sk(sk);
 
         if (tcp_may_undo(tp)) {
+                int mib_idx;
+
                 /* Happy end! We did not retransmit anything
                  * or our original transmission succeeded.
                  */
                 DBGUNDO(sk, inet_csk(sk)->icsk_ca_state == TCP_CA_Loss ? "loss" : "retrans");
                 tcp_undo_cwr(sk, 1);
                 if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss)
-                        NET_INC_STATS_BH(LINUX_MIB_TCPLOSSUNDO);
+                        mib_idx = LINUX_MIB_TCPLOSSUNDO;
                 else
-                        NET_INC_STATS_BH(LINUX_MIB_TCPFULLUNDO);
+                        mib_idx = LINUX_MIB_TCPFULLUNDO;
+
+                NET_INC_STATS_BH(mib_idx);
                 tp->undo_marker = 0;
         }
         if (tp->snd_una == tp->high_seq && tcp_is_reno(tp)) {
@@ -2560,7 +2572,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked, int flag)
         int is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));
         int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
                                     (tcp_fackets_out(tp) > tp->reordering));
-        int fast_rexmit = 0;
+        int fast_rexmit = 0, mib_idx;
 
         if (WARN_ON(!tp->packets_out && tp->sacked_out))
                 tp->sacked_out = 0;
@@ -2683,9 +2695,11 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked, int flag)
                 /* Otherwise enter Recovery state */
 
                 if (tcp_is_reno(tp))
-                        NET_INC_STATS_BH(LINUX_MIB_TCPRENORECOVERY);
+                        mib_idx = LINUX_MIB_TCPRENORECOVERY;
                 else
-                        NET_INC_STATS_BH(LINUX_MIB_TCPSACKRECOVERY);
+                        mib_idx = LINUX_MIB_TCPSACKRECOVERY;
+
+                NET_INC_STATS_BH(mib_idx);
 
                 tp->high_seq = tp->snd_nxt;
                 tp->prior_ssthresh = 0;
@@ -3700,10 +3714,14 @@ static inline int tcp_sack_extend(struct tcp_sack_block *sp, u32 seq,
 static void tcp_dsack_set(struct tcp_sock *tp, u32 seq, u32 end_seq)
 {
         if (tcp_is_sack(tp) && sysctl_tcp_dsack) {
+                int mib_idx;
+
                 if (before(seq, tp->rcv_nxt))
-                        NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOLDSENT);
+                        mib_idx = LINUX_MIB_TCPDSACKOLDSENT;
                 else
-                        NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFOSENT);
+                        mib_idx = LINUX_MIB_TCPDSACKOFOSENT;
+
+                NET_INC_STATS_BH(mib_idx);
 
                 tp->rx_opt.dsack = 1;
                 tp->duplicate_sack[0].start_seq = seq;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 8f83ab432705..edef2afe905e 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1985,14 +1985,17 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
 
                         if (sacked & TCPCB_LOST) {
                                 if (!(sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))) {
+                                        int mib_idx;
+
                                         if (tcp_retransmit_skb(sk, skb)) {
                                                 tp->retransmit_skb_hint = NULL;
                                                 return;
                                         }
                                         if (icsk->icsk_ca_state != TCP_CA_Loss)
-                                                NET_INC_STATS_BH(LINUX_MIB_TCPFASTRETRANS);
+                                                mib_idx = LINUX_MIB_TCPFASTRETRANS;
                                         else
-                                                NET_INC_STATS_BH(LINUX_MIB_TCPSLOWSTARTRETRANS);
+                                                mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS;
+                                        NET_INC_STATS_BH(mib_idx);
 
                                         if (skb == tcp_write_queue_head(sk))
                                                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 3e358cbb1247..6a480d1fd8f6 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -326,24 +326,27 @@ static void tcp_retransmit_timer(struct sock *sk)
                 goto out;
 
         if (icsk->icsk_retransmits == 0) {
+                int mib_idx;
+
                 if (icsk->icsk_ca_state == TCP_CA_Disorder ||
                     icsk->icsk_ca_state == TCP_CA_Recovery) {
                         if (tcp_is_sack(tp)) {
                                 if (icsk->icsk_ca_state == TCP_CA_Recovery)
-                                        NET_INC_STATS_BH(LINUX_MIB_TCPSACKRECOVERYFAIL);
+                                        mib_idx = LINUX_MIB_TCPSACKRECOVERYFAIL;
                                 else
-                                        NET_INC_STATS_BH(LINUX_MIB_TCPSACKFAILURES);
+                                        mib_idx = LINUX_MIB_TCPSACKFAILURES;
                         } else {
                                 if (icsk->icsk_ca_state == TCP_CA_Recovery)
-                                        NET_INC_STATS_BH(LINUX_MIB_TCPRENORECOVERYFAIL);
+                                        mib_idx = LINUX_MIB_TCPRENORECOVERYFAIL;
                                 else
-                                        NET_INC_STATS_BH(LINUX_MIB_TCPRENOFAILURES);
+                                        mib_idx = LINUX_MIB_TCPRENOFAILURES;
                         }
                 } else if (icsk->icsk_ca_state == TCP_CA_Loss) {
-                        NET_INC_STATS_BH(LINUX_MIB_TCPLOSSFAILURES);
+                        mib_idx = LINUX_MIB_TCPLOSSFAILURES;
                 } else {
-                        NET_INC_STATS_BH(LINUX_MIB_TCPTIMEOUTS);
+                        mib_idx = LINUX_MIB_TCPTIMEOUTS;
                 }
+                NET_INC_STATS_BH(mib_idx);
         }
 
         if (tcp_use_frto(sk)) {