Messages in this thread | | | From | Paul Menage <> | Date | Sun, 11 Sep 2011 21:04:55 -0700 | Subject | Re: [PATCH 3/4] threadgroup: extend threadgroup_lock() to cover exit and exec |
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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?
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