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    SubjectRe: [PATCH 3/5] device_cgroup: keep track of local group settings
    Quoting Aristeu Rozanski (aris@redhat.com):
    > In preparation for better hierarchy support, it's needed to retain the local
    > settings in order to try to reapply them after a propagated change if they're
    > still valid.
    >
    > Cc: Tejun Heo <tj@kernel.org>
    > Cc: Serge Hallyn <serge.hallyn@canonical.com>
    > Signed-off-by: Aristeu Rozanski <aris@redhat.com>
    >
    > ---
    > security/device_cgroup.c | 108 ++++++++++++++++++++++++++++++++++-------------
    > 1 file changed, 80 insertions(+), 28 deletions(-)

    Hi,

    thanks for doing this. I've got one concern though. I don't see
    any place where devcgroup_create() was updated to create the
    local exceptions list. I think we need a guarantee that at
    any time the local exceptions list will contain all the entries
    contained in the cgroup->exceptions list. Otherwise you cannot
    use the exception_add() the way you do (or you can't use RCU),
    since there could be a window between the successful addition
    of a rule to cgroup->local.exceptions and the failed addition to
    cgroup->exceptions, during which a task (since it won't need
    the mutex for devcg_allow()) could exceed allowed permissions.

    It's possible I'm misunderstanding. If you think that's the case
    just kick me and I'll take a fresh look.

    (Btw is there a git tree or gitweb view I could look at alongside
    the patchset?)

    thanks,
    -serge


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