[LEDE-DEV] [PATCH] ubus: Remove unnecessary memset calls.

[Arjen de Korte]

Citeren Rosen Penev <rosenp at gmail.com>:

> Replace malloc+memset with calloc. Cleaner and faster in extreme situations.

Calloc is definitly *not* faster than malloc + memset. Under the hood,  
calloc will call malloc, check if memory allocation was successful and  
then proceed to set all allocated memory to 0. You need to check the  
return value of malloc or calloc anyway, so this will be actually  
slower.

It *may* be considered cleaner, since it will check if the memory  
allocation succeeded before writing zeros.

> Signed-off-by: Rosen Penev <rosenp at gmail.com>
> ---
>  libubus.c  |  6 ++----
>  lua/ubus.c | 18 ++++++------------
>  2 files changed, 8 insertions(+), 16 deletions(-)
>
> diff --git a/libubus.c b/libubus.c
> index 9463522..260e40f 100644
> --- a/libubus.c
> +++ b/libubus.c
> @@ -133,7 +133,7 @@ struct ubus_lookup_request {
>  static void ubus_lookup_cb(struct ubus_request *ureq, int type,  
> struct blob_attr *msg)
>  {
>  	struct ubus_lookup_request *req;
> -	struct ubus_object_data obj;
> +	struct ubus_object_data obj = {};
>  	struct blob_attr **attr;
>
>  	req = container_of(ureq, struct ubus_lookup_request, req);
> @@ -143,7 +143,6 @@ static void ubus_lookup_cb(struct ubus_request  
> *ureq, int type, struct blob_attr
>  	    !attr[UBUS_ATTR_OBJTYPE])
>  		return;
>
> -	memset(&obj, 0, sizeof(obj));
>  	obj.id = blob_get_u32(attr[UBUS_ATTR_OBJID]);
>  	obj.path = blob_data(attr[UBUS_ATTR_OBJPATH]);
>  	obj.type_id = blob_get_u32(attr[UBUS_ATTR_OBJTYPE]);
> @@ -220,7 +219,7 @@ int ubus_register_event_handler(struct ubus_context *ctx,
>  				const char *pattern)
>  {
>  	struct ubus_object *obj = &ev->obj;
> -	struct blob_buf b2;
> +	struct blob_buf b2 = {};
>  	int ret;
>
>  	if (!obj->id) {
> @@ -236,7 +235,6 @@ int ubus_register_event_handler(struct ubus_context *ctx,
>  	}
>
>  	/* use a second buffer, ubus_invoke() overwrites the primary one */
> -	memset(&b2, 0, sizeof(b2));
>  	blob_buf_init(&b2, 0);
>  	blobmsg_add_u32(&b2, "object", obj->id);
>  	if (pattern)
> diff --git a/lua/ubus.c b/lua/ubus.c
> index 74a15b0..e9fd10e 100644
> --- a/lua/ubus.c
> +++ b/lua/ubus.c
> @@ -410,11 +410,10 @@ static int ubus_lua_load_methods(lua_State *L,  
> struct ubus_method *m)
>  	}
>
>  	/* setup the policy pointers */
> -	p = malloc(sizeof(struct blobmsg_policy) * plen);
> +	p = calloc(plen, sizeof(struct blobmsg_policy));
>  	if (!p)
>  		return 1;
>
> -	memset(p, 0, sizeof(struct blobmsg_policy) * plen);
>  	m->policy = p;
>  	lua_pushnil(L);
>  	while (lua_next(L, -2) != 0) {
> @@ -481,26 +480,23 @@ static struct ubus_object*  
> ubus_lua_load_object(lua_State *L)
>  	int midx = 0;
>
>  	/* setup object pointers */
> -	obj = malloc(sizeof(struct ubus_lua_object));
> +	obj = calloc(1, sizeof(struct ubus_lua_object));
>  	if (!obj)
>  		return NULL;
>
> -	memset(obj, 0, sizeof(struct ubus_lua_object));
>  	obj->o.name = lua_tostring(L, -2);
>
>  	/* setup method pointers */
> -	m = malloc(sizeof(struct ubus_method) * mlen);
> -	memset(m, 0, sizeof(struct ubus_method) * mlen);
> +	m = calloc(1, sizeof(struct ubus_method) * mlen);
>  	obj->o.methods = m;
>
>  	/* setup type pointers */
> -	obj->o.type = malloc(sizeof(struct ubus_object_type));
> +	obj->o.type = calloc(1, sizeof(struct ubus_object_type));
>  	if (!obj->o.type) {
>  		free(obj);
>  		return NULL;
>  	}
>
> -	memset(obj->o.type, 0, sizeof(struct ubus_object_type));
>  	obj->o.type->name = lua_tostring(L, -2);
>  	obj->o.type->id = 0;
>  	obj->o.type->methods = obj->o.methods;
> @@ -715,11 +711,10 @@ ubus_lua_load_event(lua_State *L)
>  {
>  	struct ubus_lua_event* event = NULL;
>
> -	event = malloc(sizeof(struct ubus_lua_event));
> +	event = calloc(1, sizeof(struct ubus_lua_event));
>  	if (!event)
>  		return NULL;
>
> -	memset(event, 0, sizeof(struct ubus_lua_event));
>  	event->e.cb = ubus_event_handler;
>
>  	/* update the he callback lookup table */
> @@ -818,8 +813,7 @@ ubus_lua_do_subscribe( struct ubus_context *ctx,  
> lua_State *L, const char* targe
>  		lua_error( L );
>  	}
>
> -	sub = malloc( sizeof( struct ubus_lua_subscriber ) );
> -	memset( sub, 0, sizeof( struct ubus_lua_subscriber ) );
> +	sub = calloc( 1, sizeof( struct ubus_lua_subscriber ) );
>  	if( !sub ){
>  		lua_pushstring( L, "Out of memory" );
>  		lua_error( L );