tcp_out: fix duplicate check of tcp snd_queuelen

Can be combined into a single check using LWIP_MIN.
See bug #54194

Reported-by: Andrey Vinogradov <andrey.vinogradov@teplomonitor.ru>
Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>

src/core/tcp_out.c

@@ -330,7 +330,7 @@ tcp_write_checks(struct tcp_pcb *pcb, u16_t len)
   /* If total number of pbufs on the unsent/unacked queues exceeds the
    * configured maximum, return an error */
   /* check for configured max queuelen and possible overflow */
-  if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
+  if (pcb->snd_queuelen >= LWIP_MIN(TCP_SND_QUEUELEN, (TCP_SNDQUEUELEN_OVERFLOW + 1))) {
     LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SEVERE, ("tcp_write: too long queue %"U16_F" (max %"U16_F")\n",
                 pcb->snd_queuelen, (u16_t)TCP_SND_QUEUELEN));
     TCP_STATS_INC(tcp.memerr);
@@ -656,7 +656,7 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
     /* Now that there are more segments queued, we check again if the
      * length of the queue exceeds the configured maximum or
      * overflows. */
-    if ((queuelen > TCP_SND_QUEUELEN) || (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
+    if (queuelen > LWIP_MIN(TCP_SND_QUEUELEN, TCP_SNDQUEUELEN_OVERFLOW)) {
       LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_write: queue too long %"U16_F" (%d)\n",
                   queuelen, (int)TCP_SND_QUEUELEN));
       pbuf_free(p);