Messages in this thread | | | Date | Mon, 7 Dec 2009 19:32:26 +0100 | From | Oleg Nesterov <> | Subject | Re: [rfc] "fair" rw spinlocks |
| |
On 12/05, Eric W. Biederman wrote: > > Atomically sending signal to every member of a process group, is the > big fly in the ointment I am aware of. Last time I looked I could > not see how to convert it rcu.
I am not sure, but iirc we can do this lockless (under rcu_lock). We need to modify pid_link to use list_entry and attach_pid() should add the new task to the end. Of course we need more changes, but (again iirc) this is not too hard.
> This is a pain because we occasionally signal a process group from > interrupt context.
Only send_sigio/etc does so, right?
I didn't read the previous discussion yet (will try tomorrow), sorry if I am off-topic. But I think the nastiest problem with tasklist is that it protects parent/child relationship. We need per-process lock, but first we should change ptrace to avoid this lock somehow. (this is one of the goals of ptrace-utrace, but not "immediate").
Oleg.
| |