prepare to backport unimap/minigraph chaining

kalloc.h

@@ -34,4 +34,43 @@ void km_stat(const void *_km, km_stat_t *s);
 		KREALLOC((km), (a), (m)); \
 	} while (0)
 
+#ifndef klib_unused
+#if (defined __clang__ && __clang_major__ >= 3) || (defined __GNUC__ && __GNUC__ >= 3)
+#define klib_unused __attribute__ ((__unused__))
+#else
+#define klib_unused
+#endif
+#endif /* klib_unused */
+
+#define KALLOC_POOL_INIT2(SCOPE, name, kmptype_t) \
+	typedef struct { \
+		size_t cnt, n, max; \
+		kmptype_t **buf; \
+		void *km; \
+	} kmp_##name##_t; \
+	SCOPE kmp_##name##_t *kmp_init_##name(void *km) { \
+		kmp_##name##_t *mp; \
+		KCALLOC(km, mp, 1); \
+		mp->km = km; \
+		return mp; \
+	} \
+	SCOPE void kmp_destroy_##name(kmp_##name##_t *mp) { \
+		size_t k; \
+		for (k = 0; k < mp->n; ++k) kfree(mp->km, mp->buf[k]); \
+		kfree(mp->km, mp->buf); kfree(mp->km, mp); \
+	} \
+	SCOPE kmptype_t *kmp_alloc_##name(kmp_##name##_t *mp) { \
+		++mp->cnt; \
+		if (mp->n == 0) return (kmptype_t*)kcalloc(mp->km, 1, sizeof(kmptype_t)); \
+		return mp->buf[--mp->n]; \
+	} \
+	SCOPE void kmp_free_##name(kmp_##name##_t *mp, kmptype_t *p) { \
+		--mp->cnt; \
+		if (mp->n == mp->max) KEXPAND(mp->km, mp->buf, mp->max); \
+		mp->buf[mp->n++] = p; \
+	}
+
+#define KALLOC_POOL_INIT(name, kmptype_t) \
+	KALLOC_POOL_INIT2(static inline klib_unused, name, kmptype_t)
+
 #endif