Issue using kernel linked list in user space

[Pranay Srivastava]

On Sat, Sep 19, 2015 at 10:26 PM, Gunjan Mehta <gunjanmehta08 at gmail.com> wrote:
> I have a linked list like this http://pastebin.com/bwF3jLb6 . The problem i
> am facing is i have initialized the list head and
>  then i am doing malloc for that struct object. What i need is i want to
> make struct abc_st *r as head of linked list and other nodes after it.
>
> typedef struct abc {
> char client_id[18];
>     char mac[18];
>     st_list_head list;
> }abc_st;
>
> abc_st* check_fields (abc_st *ptr)
> {
>     char cmd[500];
>     MYSQL_RES *result;
>     MYSQL_ROW row;
>     int num_rows;
>     abc_st *r=NULL,*temp=NULL;

huh? this is initialized?
>     INIT_LIST_HEAD(&r->list);   // i have intialized the head here

>
>     sprintf(cmd, "SELECT * FROM ABCD_TABLE WHERE MAC = %.4x", ptr->mac);
>         /* Running the sql query to check for fields with value in database
> */
>     if (mysql_query(abc_db.db_handle, cmd)) {
>         num_rows = -1;
>         goto done;
>     }
>     result = mysql_store_result(abc_db.db_handle);
>     if (result == NULL) {
>         num_rows = -1;
>         goto done;
>     }
>     num_rows = mysql_num_rows(result);
>
>     while ((row = mysql_fetch_row(result)))
>     {
>         r= (abc_st *)malloc(sizeof(abc_st));
>         memcpy(r->mac,row[1],strlen(row[1])+1);
>         memcpy(r->client_id,row[0],strlen(row[0])+1);
> How should i use list_add ?
>         //list_add(struct list_head *new, struct list_head *head)
> //prototype of list_add
>        // list_add(&temp->list,&r->list);  //it will go wrong here, i want
> to make r(structure r as head and then add other strutcure objects)
>      //   r->link = NULL;
>         //list_add(r, ptr);
>
>     }
> done:
>     mysql_free_result(result);
>
>     return r;
>
> }
>
>
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-- 
        ---P.K.S