On 07/17, Oleg Nesterov wrote:
>
> And, I didn't mention this yesterday, but probably the next 08/11 patch can
> have the same problem. But this is a bit more complicated because send_sigio()
> uses the same "type" both for do_each_pid_task() and as an argument passed to
> do_send_sig_info().
perhaps it can simply do
if (type <= PIDTYPE_TGID) {
rcu_read_lock();
p = pid_task(pid, PIDTYPE_PID);
send_sigio_to_task(p, fown, fd, band, type);
rcu_read_unlock();
} else {
read_lock(&tasklist_lock);
do_each_pid_task(pid, type, p) {
send_sigio_to_task(p, fown, fd, band, type);
} while_each_pid_task(pid, type, p);
read_unlock(&tasklist_lock);
}
this way we also avoid tasklist_lock in F_OWNER_TID/F_OWNER_PID case.
To clarify, it is not that I think any sane application can do
fcntl(F_OWNER_PID, thread_tid) but still this is a user-visible change
we can easily avoid.
Oleg.
