diff --git a/libleak.c b/libleak.c
index 55a1458..ed653b0 100644
--- a/libleak.c
+++ b/libleak.c
@@ -46,16 +46,16 @@ static long conf_start_ms = 0;
 
 
 /* ### hooking symbols */
-static void *(*leak_real_malloc)(size_t size);
-static void (*leak_real_free)(void *ptr);
-static void *(*leak_real_calloc)(size_t nmemb, size_t size);
-static void *(*leak_real_realloc)(void *ptr, size_t size);
-static pid_t (*leak_real_fork)(void); /* open new log file for new process */
+static void *(*leak_real_malloc)(size_t size) = NULL;
+static void (*leak_real_free)(void *ptr) = NULL;
+static void *(*leak_real_calloc)(size_t nmemb, size_t size) = NULL;
+static void *(*leak_real_realloc)(void *ptr, size_t size) = NULL;
+static pid_t (*leak_real_fork)(void) = NULL; /* open new log file for new process */
 
 
 /* ### running flags */
-static bool leak_inited;
-static __thread bool leak_in_process;
+static bool leak_inited = false;
+static __thread bool leak_in_process = false;
 static FILE *leak_log_filp;
 
 
@@ -191,7 +191,7 @@ static const char *lib_maps_search(uintptr_t pc)
 
 /* ### a simple memory allocation used before init() */
 
-static uint8_t tmp_buffer[10 * 1024 * 1024]; /* increase this if need */
+static uint8_t tmp_buffer[1024 * 1024]; /* increase this if necessary */
 static uint8_t *tmp_buf_pos = tmp_buffer;
 static void *tmp_malloc(size_t size)
 {
@@ -311,6 +311,22 @@ static void __attribute__((constructor))init(void)
 		conf_start_ms = leak_now_ms() + atoi(ev) * 1000;
 	}
 
+	/* hook symbols */
+	leak_real_malloc = dlsym(RTLD_NEXT, "malloc");
+	assert(leak_real_malloc != NULL);
+
+	leak_real_realloc = dlsym(RTLD_NEXT, "realloc");
+	assert(leak_real_realloc != NULL);
+
+	leak_real_calloc = dlsym(RTLD_NEXT, "calloc");
+	assert(leak_real_calloc != NULL);
+
+	leak_real_free = dlsym(RTLD_NEXT, "free");
+	assert(leak_real_free != NULL);
+
+	leak_real_fork = dlsym(RTLD_NEXT, "fork");
+	assert(leak_real_fork != NULL);
+
 	/* init dict and memory pool */
 	leak_callstack_dict = wuy_dict_new_func(leak_callstack_hash,
 			leak_callstack_equal,
@@ -328,22 +344,6 @@ static void __attribute__((constructor))init(void)
 	/* init backtrace state */
 	btstate = backtrace_create_state(NULL, 1, NULL, NULL);
 
-	/* hook symbols */
-	leak_real_malloc = dlsym(RTLD_NEXT, "malloc");
-	assert(leak_real_malloc != NULL);
-
-	leak_real_realloc = dlsym(RTLD_NEXT, "realloc");
-	assert(leak_real_realloc != NULL);
-
-	leak_real_calloc = dlsym(RTLD_NEXT, "calloc");
-	assert(leak_real_calloc != NULL);
-
-	leak_real_free = dlsym(RTLD_NEXT, "free");
-	assert(leak_real_free != NULL);
-
-	leak_real_fork = dlsym(RTLD_NEXT, "fork");
-	assert(leak_real_fork != NULL);
-
 	/* log file */
 	char log_fname[100];
 	sprintf(log_fname, "%s.%d", conf_log_file, getpid());
@@ -474,13 +474,16 @@ static bool leak_enabled_check(void)
 static int leak_backtrace_simple_cb(void *data, uintptr_t pc)
 {
 	if (pc == (uintptr_t)-1) {
-		return 0;
+		return 1;
 	}
 	if (conf_lib_blacklist != NULL && lib_maps_search(pc) == NULL) {
-		return 1;
+		return -1;
 	}
 
 	struct leak_callstack *current = data;
+	if (current->ip_num > 100) {
+		return 1;
+	}
 	current->ips[current->ip_num++] = pc;
 	return 0;
 }
@@ -491,7 +494,7 @@ static struct leak_callstack *leak_current(void)
 
 	struct leak_callstack current[20];
 	current->ip_num = 0;
-	if (backtrace_simple(btstate, 2, leak_backtrace_simple_cb, NULL, current) != 0) {
+	if (backtrace_simple(btstate, 2, leak_backtrace_simple_cb, NULL, current) < 0) {
 		return NULL;
 	}