Increased LWIP main worker thread stack size for debug builds

LWIP stack is configured to be 1200 as default. Without debug enabled,
maximum stack size used for asynchronous DNS operations is 880 bytes. With
debug enabled maximum used stack size is 1248. Added configuration
to LWIP to increase stack size by 25 percent when debug is enabled on build.

Author: Mika Leppänen

features/FEATURE_LWIP/lwip-interface/lwipopts.h

@@ -90,15 +90,22 @@
 #define DEFAULT_RAW_RECVMBOX_SIZE   8
 #define DEFAULT_ACCEPTMBOX_SIZE     8
 
+// Thread stacks use 8-byte alignment
+#define LWIP_ALIGN_UP(pos, align) ((pos) % (align) ? (pos) +  ((align) - (pos) % (align)) : (pos))
+
 // Thread stack size for lwip tcpip thread
 #ifndef MBED_CONF_LWIP_TCPIP_THREAD_STACKSIZE
 #define MBED_CONF_LWIP_TCPIP_THREAD_STACKSIZE      1200
 #endif
 
 #ifdef LWIP_DEBUG
-#define TCPIP_THREAD_STACKSIZE      MBED_CONF_LWIP_TCPIP_THREAD_STACKSIZE*2
+// For LWIP debug, double the stack
+#define TCPIP_THREAD_STACKSIZE      LWIP_ALIGN_UP(MBED_CONF_LWIP_TCPIP_THREAD_STACKSIZE*2, 8)
+#elif MBED_DEBUG
+// When debug is enabled on the build increase stack 25 percent
+#define TCPIP_THREAD_STACKSIZE      LWIP_ALIGN_UP(MBED_CONF_LWIP_TCPIP_THREAD_STACKSIZE + MBED_CONF_LWIP_TCPIP_THREAD_STACKSIZE / 4, 8)
 #else
-#define TCPIP_THREAD_STACKSIZE      MBED_CONF_LWIP_TCPIP_THREAD_STACKSIZE
+#define TCPIP_THREAD_STACKSIZE      LWIP_ALIGN_UP(MBED_CONF_LWIP_TCPIP_THREAD_STACKSIZE, 8)
 #endif
 
 #define TCPIP_THREAD_PRIO           (osPriorityNormal)
@@ -114,11 +121,11 @@
 #endif
 
 #ifdef LWIP_DEBUG
-#define DEFAULT_THREAD_STACKSIZE    MBED_CONF_LWIP_DEFAULT_THREAD_STACKSIZE*2
-#define PPP_THREAD_STACK_SIZE       MBED_CONF_LWIP_PPP_THREAD_STACKSIZE*2
+#define DEFAULT_THREAD_STACKSIZE    LWIP_ALIGN_UP(MBED_CONF_LWIP_DEFAULT_THREAD_STACKSIZE*2, 8)
+#define PPP_THREAD_STACK_SIZE       LWIP_ALIGN_UP(MBED_CONF_LWIP_PPP_THREAD_STACKSIZE*2, 8)
 #else
-#define DEFAULT_THREAD_STACKSIZE    MBED_CONF_LWIP_DEFAULT_THREAD_STACKSIZE
-#define PPP_THREAD_STACK_SIZE       MBED_CONF_LWIP_PPP_THREAD_STACKSIZE
+#define DEFAULT_THREAD_STACKSIZE    LWIP_ALIGN_UP(MBED_CONF_LWIP_DEFAULT_THREAD_STACKSIZE, 8)
+#define PPP_THREAD_STACK_SIZE       LWIP_ALIGN_UP(MBED_CONF_LWIP_PPP_THREAD_STACKSIZE, 8)
 #endif
 
 #define MEMP_NUM_SYS_TIMEOUT        16