Re: [PATCH] task: Make task list manipulations RCU safe.

[Eric W. Biederman]

Oleg Nesterov <oleg@xxxxxxxxxx> writes:

> "Eric W. Biederman" wrote:
>> 
>> Oleg Nesterov <oleg@xxxxxxxxxx> writes:
>> 
>> > Some questions.
>> >
>> > first_tgid:
>> >       ...
>> >       for (; pos && pid_alive(pos); pos = next_task(pos))
>> >
>> > I think this patch makes this 'pid_alive(pos)' unneeded?
>> 
>> Close.  The problem is that we could have slept with the
>> count elevated on start before we do rcu_read_lock().
>
> Yes, we could have slept. But (unlike next_tgid) this loop
> starts from pos=init_task or from pos=find_task_by_pid()
> and we are doing find_task_by_pid under rcu_read_lock() ?

Yes.  We are sorry. The bits of code blurred in the discussion.

Eric
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/