tcp_out: Use LWIP_DBG_LEVEL_SERIOUS instead of magic number

Trivial clean up to avoid using magic number.

Signed-off-by: Axel Lin <axel.lin@ingics.com>

src/core/tcp_out.c

@@ -177,7 +177,7 @@ tcp_create_segment(struct tcp_pcb *pcb, struct pbuf *p, u8_t flags, u32_t seqno,
   u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
 
   if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no memory.\n"));
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_create_segment: no memory.\n"));
     pbuf_free(p);
     return NULL;
   }
@@ -199,7 +199,7 @@ tcp_create_segment(struct tcp_pcb *pcb, struct pbuf *p, u8_t flags, u32_t seqno,
 
   /* build TCP header */
   if (pbuf_header(p, TCP_HLEN)) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
     TCP_STATS_INC(tcp.err);
     tcp_seg_free(seg);
     return NULL;
@@ -495,7 +495,7 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
       if (apiflags & TCP_WRITE_FLAG_COPY) {
         /* Data is copied */
         if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
-          LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2,
+          LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
                       ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
                        seglen));
           goto memerr;
@@ -510,7 +510,7 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
       } else {
         /* Data is not copied */
         if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
-          LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2,
+          LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
                       ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
           goto memerr;
         }
@@ -554,7 +554,7 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
       /* If copy is set, memory should be allocated and data copied
        * into pbuf */
       if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, mss_local, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
-        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
+        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
         goto memerr;
       }
       LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
@@ -571,7 +571,7 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
       LWIP_ASSERT("oversize == 0", oversize == 0);
 #endif /* TCP_OVERSIZE */
       if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
-        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
+        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
         goto memerr;
       }
 #if TCP_CHECKSUM_ON_COPY
@@ -590,7 +590,7 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
         /* If allocation fails, we have to deallocate the data pbuf as
          * well. */
         pbuf_free(p2);
-        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for header pbuf\n"));
+        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("tcp_write: could not allocate memory for header pbuf\n"));
         goto memerr;
       }
       /* Concatenate the headers and data pbufs together. */
@@ -603,7 +603,7 @@ tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
      * length of the queue exceeds the configured maximum or
      * overflows. */
     if ((queuelen > TCP_SND_QUEUELEN) || (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
-      LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: queue too long %"U16_F" (%d)\n",
+      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);
       goto memerr;