From 6adeb706a699da10f2841eea3671546407ec413a Mon Sep 17 00:00:00 2001
From: goldsimon <goldsimon@gmx.de>
Date: Tue, 19 Jul 2016 10:38:01 +0200
Subject: [PATCH] change tcp_pcb->acked to be a global variable: used in one
 call stack only (idea by Ambroz Bizjak)

---
 src/core/tcp_in.c      | 44 ++++++++++++++++++++++--------------------
 src/include/lwip/tcp.h |  2 --
 2 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/src/core/tcp_in.c b/src/core/tcp_in.c
index fbe1d1f3..7eab9a77 100644
--- a/src/core/tcp_in.c
+++ b/src/core/tcp_in.c
@@ -75,8 +75,9 @@ static u16_t tcphdr_opt1len;
 static u8_t* tcphdr_opt2;
 static u16_t tcp_optidx;
 static u32_t seqno, ackno;
-static u8_t flags;
+static tcpwnd_size_t recv_acked;
 static u16_t tcplen;
+static u8_t flags;
 
 static u8_t recv_flags;
 static struct pbuf *recv_data;
@@ -346,6 +347,7 @@ tcp_input(struct pbuf *p, struct netif *inp)
 
     recv_data = NULL;
     recv_flags = 0;
+    recv_acked = 0;
 
     if (flags & TCP_PSH) {
       p->flags |= PBUF_FLAG_PUSH;
@@ -380,25 +382,25 @@ tcp_input(struct pbuf *p, struct netif *inp)
         /* If the application has registered a "sent" function to be
            called when new send buffer space is available, we call it
            now. */
-        if (pcb->acked > 0) {
-          u16_t acked;
+        if (recv_acked > 0) {
+          u16_t acked16;
 #if LWIP_WND_SCALE
-          /* pcb->acked is u32_t but the sent callback only takes a u16_t,
+          /* recv_acked is u32_t but the sent callback only takes a u16_t,
              so we might have to call it multiple times. */
-          u32_t pcb_acked = pcb->acked;
-          while (pcb_acked > 0) {
-            acked = (u16_t)LWIP_MIN(pcb_acked, 0xffffu);
-            pcb_acked -= acked;
+          u32_t acked = recv_acked;
+          while (acked > 0) {
+            acked16 = (u16_t)LWIP_MIN(acked, 0xffffu);
+            acked -= acked16;
 #else
           {
-            acked = pcb->acked;
+            acked16 = recv_acked;
 #endif
-            TCP_EVENT_SENT(pcb, (u16_t)acked, err);
+            TCP_EVENT_SENT(pcb, (u16_t)acked16, err);
             if (err == ERR_ABRT) {
               goto aborted;
             }
           }
-          pcb->acked = 0;
+          recv_acked = 0;
         }
         if (recv_flags & TF_CLOSED) {
           /* The connection has been closed and we will deallocate the
@@ -843,8 +845,8 @@ tcp_process(struct tcp_pcb *pcb)
         pcb->ssthresh = LWIP_TCP_INITIAL_SSTHRESH(pcb);
 
         /* Prevent ACK for SYN to generate a sent event */
-        if (pcb->acked != 0) {
-          pcb->acked--;
+        if (recv_acked != 0) {
+          recv_acked--;
         }
 
         pcb->cwnd = LWIP_TCP_CALC_INITIAL_CWND(pcb->mss);
@@ -1060,7 +1062,7 @@ tcp_receive(struct tcp_pcb *pcb)
 
     /* Clause 1 */
     if (TCP_SEQ_LEQ(ackno, pcb->lastack)) {
-      pcb->acked = 0;
+      recv_acked = 0;
       /* Clause 2 */
       if (tcplen == 0) {
         /* Clause 3 */
@@ -1111,9 +1113,9 @@ tcp_receive(struct tcp_pcb *pcb)
 
       /* Update the send buffer space. Diff between the two can never exceed 64K
          unless window scaling is used. */
-      pcb->acked = (tcpwnd_size_t)(ackno - pcb->lastack);
+      recv_acked = (tcpwnd_size_t)(ackno - pcb->lastack);
 
-      pcb->snd_buf += pcb->acked;
+      pcb->snd_buf += recv_acked;
 
       /* Reset the fast retransmit variables. */
       pcb->dupacks = 0;
@@ -1158,8 +1160,8 @@ tcp_receive(struct tcp_pcb *pcb)
         LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"TCPWNDSIZE_F" ... ", (tcpwnd_size_t)pcb->snd_queuelen));
         LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
         /* Prevent ACK for FIN to generate a sent event */
-        if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
-          pcb->acked--;
+        if ((recv_acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
+          recv_acked--;
         }
 
         pcb->snd_queuelen -= pbuf_clen(next->p);
@@ -1190,7 +1192,7 @@ tcp_receive(struct tcp_pcb *pcb)
 #endif /* LWIP_IPV6 && LWIP_ND6_TCP_REACHABILITY_HINTS*/
     } else {
       /* Out of sequence ACK, didn't really ack anything */
-      pcb->acked = 0;
+      recv_acked = 0;
       tcp_send_empty_ack(pcb);
     }
 
@@ -1217,8 +1219,8 @@ tcp_receive(struct tcp_pcb *pcb)
       LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_receive: queuelen %"TCPWNDSIZE_F" ... ", (tcpwnd_size_t)pcb->snd_queuelen));
       LWIP_ASSERT("pcb->snd_queuelen >= pbuf_clen(next->p)", (pcb->snd_queuelen >= pbuf_clen(next->p)));
       /* Prevent ACK for FIN to generate a sent event */
-      if ((pcb->acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
-        pcb->acked--;
+      if ((recv_acked != 0) && ((TCPH_FLAGS(next->tcphdr) & TCP_FIN) != 0)) {
+        recv_acked--;
       }
       pcb->snd_queuelen -= pbuf_clen(next->p);
       tcp_seg_free(next);
diff --git a/src/include/lwip/tcp.h b/src/include/lwip/tcp.h
index e426a35c..29ff0319 100644
--- a/src/include/lwip/tcp.h
+++ b/src/include/lwip/tcp.h
@@ -264,8 +264,6 @@ struct tcp_pcb {
   tcpwnd_size_t snd_wnd;   /* sender window */
   tcpwnd_size_t snd_wnd_max; /* the maximum sender window announced by the remote host */
 
-  tcpwnd_size_t acked;
-
   tcpwnd_size_t snd_buf;   /* Available buffer space for sending (in bytes). */
 #define TCP_SNDQUEUELEN_OVERFLOW (0xffffU-3)
   u16_t snd_queuelen; /* Number of pbufs currently in the send buffer. */