/*  invoke cmd->callback function */
        pcmd_callback = cmd_callback[pcmd->cmdcode].callback;
-       if (pcmd_callback == NULL)
+       if (!pcmd_callback)
                r8712_free_cmd_obj(pcmd);
        else
                pcmd_callback(padapter, pcmd);
 
        /*  invoke cmd->callback function */
        pcmd_callback = cmd_callback[pcmd->cmdcode].callback;
-       if (pcmd_callback == NULL)
+       if (!pcmd_callback)
                r8712_free_cmd_obj(pcmd);
        else
                pcmd_callback(padapter, pcmd);
        if (pcmd->rsp && pcmd->rspsz > 0)
                memcpy(pcmd->rsp, (u8 *)&val, pcmd->rspsz);
        pcmd_callback = cmd_callback[pcmd->cmdcode].callback;
-       if (pcmd_callback == NULL)
+       if (!pcmd_callback)
                r8712_free_cmd_obj(pcmd);
        else
                pcmd_callback(padapter, pcmd);
        struct cmd_obj *pcmd  = (struct cmd_obj *)pbuf;
 
        pcmd_callback = cmd_callback[pcmd->cmdcode].callback;
-       if (pcmd_callback == NULL)
+       if (!pcmd_callback)
                r8712_free_cmd_obj(pcmd);
        else
                pcmd_callback(padapter, pcmd);
        if (pcmd->rsp && pcmd->rspsz > 0)
                memcpy(pcmd->rsp, (u8 *)&val, pcmd->rspsz);
        pcmd_callback = cmd_callback[pcmd->cmdcode].callback;
-       if (pcmd_callback == NULL)
+       if (!pcmd_callback)
                r8712_free_cmd_obj(pcmd);
        else
                pcmd_callback(padapter, pcmd);
        struct cmd_obj *pcmd  = (struct cmd_obj *)pbuf;
 
        pcmd_callback = cmd_callback[pcmd->cmdcode].callback;
-       if (pcmd_callback == NULL)
+       if (!pcmd_callback)
                r8712_free_cmd_obj(pcmd);
        else
                pcmd_callback(padapter, pcmd);
 {
        struct cmd_obj *pcmd_r;
 
-       if (pcmd == NULL)
+       if (!pcmd)
                return pcmd;
        pcmd_r = NULL;
 
        /* free all cmd_obj resources */
        do {
                pcmd = r8712_dequeue_cmd(&(pcmdpriv->cmd_queue));
-               if (pcmd == NULL)
+               if (!pcmd)
                        break;
                r8712_free_cmd_obj(pcmd);
        } while (1);
        void (*event_callback)(struct _adapter *dev, u8 *pbuf);
        struct  evt_priv *pevt_priv = &(padapter->evtpriv);
 
-       if (peventbuf == NULL)
+       if (!peventbuf)
                goto _abort_event_;
        evt_sz = (u16)(le32_to_cpu(*peventbuf) & 0xffff);
        evt_seq = (u8)((le32_to_cpu(*peventbuf) >> 24) & 0x7f);