memp: cleaned up MEMP_MEM_MALLOC:

- support memp stats when MEMP_MEM_MALLOC==1 (bug #48442);
- hide MEMP_MEM_MALLOC in memp.c instead of messing up the header file;
- make MEMP_OVERFLOW_CHECK work when MEMP_MEM_MALLOC==1

src/include/lwip/memp.h

@@ -60,21 +60,14 @@ extern const struct memp_desc* const memp_pools[MEMP_MAX];
 
 #if MEMP_MEM_MALLOC
 
-#include "lwip/mem.h"
-
-#define memp_init()
-#define memp_malloc(type)     mem_malloc(memp_pools[type]->size)
-#define memp_free(type, mem)  mem_free(mem)
-
 #define LWIP_MEMPOOL_DECLARE(name,num,size,desc) \
+  LWIP_MEMPOOL_DECLARE_STATS_INSTANCE(memp_stats_ ## name) \
   const struct memp_desc memp_ ## name = { \
+    DECLARE_LWIP_MEMPOOL_DESC(desc) \
+    LWIP_MEMPOOL_DECLARE_STATS_REFERENCE(memp_stats_ ## name) \
     LWIP_MEM_ALIGN_SIZE(size) \
   };
 
-#define LWIP_MEMPOOL_INIT(name)
-#define LWIP_MEMPOOL_ALLOC(name)   mem_malloc(memp_ ## name.size)
-#define LWIP_MEMPOOL_FREE(name, x) mem_free(x)
-
 #else /* MEMP_MEM_MALLOC */
 
 /** Declare a private memory pool 
@@ -102,14 +95,16 @@ extern const struct memp_desc* const memp_pools[MEMP_MAX];
   static struct memp *memp_tab_ ## name; \
     \
   const struct memp_desc memp_ ## name = { \
-    LWIP_MEM_ALIGN_SIZE(size), \
-    LWIP_MEMPOOL_DECLARE_STATS_REFERENCE(memp_stats_ ## name) \
-    (num), \
     DECLARE_LWIP_MEMPOOL_DESC(desc) \
+    LWIP_MEMPOOL_DECLARE_STATS_REFERENCE(memp_stats_ ## name) \
+    LWIP_MEM_ALIGN_SIZE(size), \
+    (num), \
     memp_memory_ ## name ## _base, \
     &memp_tab_ ## name \
   };
 
+#endif /* MEMP_MEM_MALLOC */
+
 /** Initialize a private memory pool */
 #define LWIP_MEMPOOL_INIT(name)    memp_init_pool(&memp_ ## name)
 /** Allocate from a private memory pool */
@@ -139,8 +134,6 @@ void *memp_malloc(memp_t type);
 #endif
 void  memp_free(memp_t type, void *mem);
 
-#endif /* MEMP_MEM_MALLOC */
-
 #ifdef __cplusplus
 }
 #endif

src/include/lwip/priv/memp_priv.h

@@ -87,6 +87,7 @@ extern "C" {
 
 #endif /* MEMP_OVERFLOW_CHECK */
 
+#if !MEMP_MEM_MALLOC || MEMP_OVERFLOW_CHECK
 struct memp {
   struct memp *next;
 #if MEMP_OVERFLOW_CHECK
@@ -94,6 +95,7 @@ struct memp {
   int line;
 #endif /* MEMP_OVERFLOW_CHECK */
 };
+#endif /* !MEMP_MEM_MALLOC || MEMP_OVERFLOW_CHECK */
 
 #if MEM_USE_POOLS
 /* Use a helper type to get the start and end of the user "memory pools" for mem_malloc */
@@ -126,23 +128,22 @@ typedef enum {
 
 /** Memory pool descriptor */
 struct memp_desc {
-  /** Element size */
-  u16_t size;
-
+#if defined(LWIP_DEBUG) || MEMP_OVERFLOW_CHECK || LWIP_STATS_DISPLAY
+  /** Textual description */
+  const char *desc;
+#endif /* LWIP_DEBUG || MEMP_OVERFLOW_CHECK || LWIP_STATS_DISPLAY */
 #if MEMP_STATS
   /** Statistics */
   struct stats_mem *stats;
 #endif
 
+  /** Element size */
+  u16_t size;
+
 #if !MEMP_MEM_MALLOC
   /** Number of elements */
   u16_t num;
 
-#if defined(LWIP_DEBUG) || MEMP_OVERFLOW_CHECK || LWIP_STATS_DISPLAY
-  /** Textual description */
-  const char *desc;
-#endif /* LWIP_DEBUG || MEMP_OVERFLOW_CHECK || LWIP_STATS_DISPLAY */
-
   /** Base address */
   u8_t *base;
 

src/include/lwip/priv/memp_std.h

@@ -1,6 +1,9 @@
 /**
  * @file
  * lwIP internal memory pools (do not use in application code)
+ * This file is deliberately included multiple times: once with empty
+ * definition of LWIP_MEMPOOL() to handle all includes and multiple times
+ * to build up various lists of mem pools.
  */
 
 /*