[Devel] Re: [RFC] [PATCH v3 1/2] cgroups: read-write lock
CLONE_THREAD forking per threadgroup
bblum at andrew.cmu.edu
Wed Jul 28 04:29:53 EDT 2010
On Mon, Jun 28, 2010 at 11:43:59AM -0400, Ben Blum wrote:
> On Mon, Jun 28, 2010 at 04:10:31PM +0900, KAMEZAWA Hiroyuki wrote:
> > By the way, IMHO, hiding lock in cgroup_fork() and cgroup_post_fork() doesn't
> > seem good idea. How about a code like this ?
> > read_lock_thread_clone(current);
> > cgroup_fork();
> > .....
> > cgroup_post_fork();
> > read_unlock_thrad_clone(current);
> > We may have chances to move these lock to better position if cgroup is
> > an only user.
> I didn't do that out of a desire to change fork.c as little as possible,
> but that does look better than what I've got. Those two functions should
> be in fork.c under #ifdef CONFIG_CGROUPS.
I'm looking at this now and am not sure where the best place to put
1) Don't make new functions, just put:
if (clone_flags & CLONE_THREAD)
directly in copy_process() in fork.c. Simplest, but uglifies the code.
2) Make static helper functions in fork.c. Good, but not consistent with
directly using the lock in write-side (attach_proc).
3) Define inline functions under #ifdef CONFIG_CGROUPS in sched.h, just
under the declaration of the lock. Most robust, but I'm hesitant to add
unneeded stuff to such a popular header file.
> > Thanks,
> > -Kame
> -- Ben
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