Move cgroup->sibling unlinking from cgroup_destroy_css_killed() to cgroup_put(). This is later but still before the RCU grace period, so it doesn't break css_next_child() although there now is a larger window in which a dead cgroup is visible during css iteration. As css iteration always could have included offline csses, this doesn't affect correctness; however, it does make css_next_child() fall back to reiterting mode more often. This also makes cgroup_put() directly take cgroup_mutex, which limits where it can be called from. These are not immediately problematic and will be dealt with later.
This change enables simplification of cgroup destruction path. Signed-off-by: Tejun Heo <[email protected]> --- kernel/cgroup.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 45149b7..87ea2ce 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1056,6 +1056,11 @@ static void cgroup_put(struct cgroup *cgrp) if (WARN_ON_ONCE(cgrp->parent && !cgroup_is_dead(cgrp))) return; + /* delete this cgroup from parent->children */ + mutex_lock(&cgroup_mutex); + list_del_rcu(&cgrp->sibling); + mutex_unlock(&cgroup_mutex); + cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id); cgrp->id = -1; @@ -4560,9 +4565,6 @@ static void cgroup_destroy_css_killed(struct cgroup *cgrp) { lockdep_assert_held(&cgroup_mutex); - /* delete this cgroup from parent->children */ - list_del_rcu(&cgrp->sibling); - cgroup_put(cgrp); } -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
