Messages in this thread | | | Date | Wed, 4 Jan 2012 11:36:14 -0800 | From | Mandeep Singh Baines <> | Subject | Re: Q: cgroup: Questions about possible issues in cgroup locking |
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Oleg Nesterov (oleg@redhat.com) wrote: > On 12/21, Frederic Weisbecker wrote: > > > > On Wed, Dec 21, 2011 at 11:24:13AM -0800, Mandeep Singh Baines wrote: > > > > > > If you call exec from a thread other than g, g is now unlinked. So > > > "t != g" will always be true. If you then pthread_create, you now > > > have two threads so "t != __prev" will also always be true. So > > > you now have an infinite loop. > > > > Oh you're right. > > > > But then we can't use t != t->group_leader because that assumes while_each_thread() > > started on the leader. > > Yes, this can't work. > > Besides, we need more burriers to rely on the ->group_leader check. > > See http://marc.info/?t=127688987300002 >
I went through the thread. Were there any other concerns other than requiring that you start with the group_leader and the barrier?
You could modify zap_other_threads to start with the group leader by skipping p:
if (p == t) continue;
> in particular, http://marc.info/?l=linux-kernel&m=127714242731448 > I think this should work, but then we should do something with the > users like zap_threads(). >
With that patch, won't you potentially miss the exec thread if an exec occurs while you're iterating over the list? Is that OK?
Regards, Mandeep
> Oleg. >
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