Em Mon, Mar 30, 2015 at 01:49:07PM +0200, Jiri Olsa escreveu:
> On Mon, Mar 30, 2015 at 01:21:08PM +0200, Jiri Olsa wrote:
> > > looks like race among __machine__findnew_thread and thread__put
> > > over the machine->threads rb_tree insert/removal
> > > is there a reason why thread__put does not erase itself from
> > > machine->threads?
> that was the reason.. we do this separately.. not in thread__put..
> is there a reason for this? ;-)
> testing attached patch..
> void thread__put(struct thread *thread)
> {
> if (thread && --thread->refcnt == 0) {
> + struct machine *machine = thread->machine;
> +
> list_del_init(&thread->node);
> +
> + pthread_mutex_lock(&machine->threads_lock);
> + rb_erase(&thread->rb_node, &machine->threads);
> + pthread_mutex_unlock(&machine->threads_lock);
> +
> thread__delete(thread);
You can't do that, look at the definition of struct thread:
struct thread {
union {
struct rb_node rb_node;
struct list_head node;
};
I.e. a thread can't be at the same time in the rbtree (live threads) and
on the list (dead threads).
When the thread dies (PERF_RECORD_EXIT) we transition it from the live
threads rb_tree to the dead_threads list, where it will wait till the
last hist_entry holding a reference to it to call thread__put(), when we
will want to remove it _only_ from the dead_threads _list_.
- Arnaldo
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