Messages in this thread | | | Date | Tue, 13 Sep 2011 16:54:44 +0900 | From | Tejun Heo <> | Subject | Re: [PATCH 3/4] threadgroup: extend threadgroup_lock() to cover exit and exec |
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On Sun, Sep 11, 2011 at 09:04:55PM -0700, Paul Menage wrote: > On Sun, Sep 4, 2011 at 11:01 AM, Tejun Heo <htejun@gmail.com> wrote: > > From: Tejun Heo <tj@kernel.org> > > > > threadgroup_lock() protected only protected against new addition to > > the threadgroup, which was inherently somewhat incomplete and > > problematic for its only user cgroup. On-going migration could race > > against exec and exit leading to interesting problems - the symmetry > > between various attach methods, task exiting during method execution, > > ->exit() racing against attach methods, migrating task switching basic > > properties during exec and so on. > > > > This patch extends threadgroup_lock() such that it protects against > > all three threadgroup altering operations - fork, exit and exec. For > > exit, threadgroup_change_begin/end() calls are added to exit path. > > For exec, threadgroup_[un]lock() are updated to also grab and release > > cred_guard_mutex. > > Can you add a comment (either in the commit or in the code) about why > the cred_guard_mutex change is necessary? Is it simply that exec takes > cred_guard_mutex and hence this excludes exec, or is there something > more subtle?
Will do so. It's just for the exclusion of cred_guard_mutex. Maybe we better rename it to exec_mutex or something, I don't know.
Thanks.
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