Delete an object in multi-thread situation

[parsap]

I have to delete an object at a time that I don't know it's held by another thread(s) or not.
For example

static void foo(CLASS* ref){
pthread_mutex_lock(&l);//[POINT-A]
    //using ref
    //do something thread safe
pthread_mutex_unlock(&l);
delete ref;// how can I find out there is no any thread held at [POINT-A]
}

Thanks in advance

[Peter87]

Sounds like a job for std::shared_ptr.

[parsap]

Sounds like a job for std::shared_ptr.

Would you please give an example? or a link? many thanks dear.