Messages in this thread | | | Date | Wed, 12 Oct 2011 21:07:54 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 3/4] threadgroup: extend threadgroup_lock() to cover exit and exec |
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On 10/12, Ben Blum wrote: > > On Wed, Oct 12, 2011 at 08:29:05PM +0200, Oleg Nesterov wrote: > > On 10/12, Ben Blum wrote: > > > > > > On Wed, Oct 12, 2011 at 07:51:04PM +0200, Oleg Nesterov wrote: > > > > > > > > > Also, it makes the mechanism unnecessarily cgroup-specific without > > > > > gaining much if anything. > > > > > > > > Yes! And _personally_ I think it should be cgroup-specific, that is > > > > why I dislike the very fact do_exit() uses it directly. To me it would > > > > be cleaner to shift it into cgroup hooks. Yes, sure, this is subjective. > > > > > > In the fork path, threadgroup_fork_read_...() is also called directly, > > > not through cgroups. Would that change too? > > > > Well, if you ask me, I'd prefer to move lock/unlock into > > cgroup_fork/cgroup_post_fork ;) Although the error path plays with it > > too. But this is minor. > > > > > > In fact I still hope we can kill this sem altogether, but so far I have > > > > no idea how we can do this. We do need the new per-process lock to > > > > protect (in particular) ->thread_group. It is quite possible that it > > > > should be rw_semaphore. But in this case we down_write(), not _read > > > > in exit/fork paths, and its scope should be small. > > > > > > I'm confused - taking a big rwsem for writing in the fork/exit paths? > > > > Yes, we need the new lock to avoid tasklist_lock. > > To avoid tasklist_lock in the cgroup path, or in the fork/exit path?
Sorry for confusion ;) I meant exit_notify/do_wait-like things. I didn't mean cgroup at all.
Oleg.
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