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

[Rosen Penev]

I beg to differ. https://vorpus.org/blog/why-does-calloc-exist/

Section 2.

On Tue, Nov 7, 2017 at 12:46 PM, Arjen de Korte <arjen+lede at de-korte.org> wrote:
> 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 );
>
>
>
>
>
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