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Commit ee7eafc9 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-3.12-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 

Pull cgroup fixes from Tejun Heo:
 "Two late fixes for cgroup.

  One fixes descendant walk introduced during this rc1 cycle.  The other
  fixes a post 3.9 bug during task attach which can lead to hang.  Both
  fixes are critical and the fixes are relatively straight-forward"

* 'for-3.12-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: fix to break the while loop in cgroup_attach_task() correctly
  cgroup: fix cgroup post-order descendant walk of empty subtree
parents 0df651a0 ea84753c

kernel/cgroup.c

+6 −8
Original line number Original line Diff line number Diff line
@@ -2039,7 +2039,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, 




		/* @tsk either already exited or can't exit until the end */

		/* @tsk either already exited or can't exit until the end */

		if (tsk->flags & PF_EXITING)

		if (tsk->flags & PF_EXITING)

			continue;

			goto next;





		/* as per above, nr_threads may decrease, but not increase. */

		/* as per above, nr_threads may decrease, but not increase. */

		BUG_ON(i >= group_size);

		BUG_ON(i >= group_size);
@@ -2047,7 +2047,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, 
		ent.cgrp = task_cgroup_from_root(tsk, root);

		ent.cgrp = task_cgroup_from_root(tsk, root);

		/* nothing to do if this task is already in the cgroup */

		/* nothing to do if this task is already in the cgroup */

		if (ent.cgrp == cgrp)

		if (ent.cgrp == cgrp)

			continue;

			goto next;

		/*

		/*

		 * saying GFP_ATOMIC has no effect here because we did prealloc

		 * saying GFP_ATOMIC has no effect here because we did prealloc

		 * earlier, but it's good form to communicate our expectations.

		 * earlier, but it's good form to communicate our expectations.
@@ -2055,7 +2055,7 @@ static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, 
		retval = flex_array_put(group, i, &ent, GFP_ATOMIC);

		retval = flex_array_put(group, i, &ent, GFP_ATOMIC);

		BUG_ON(retval != 0);

		BUG_ON(retval != 0);

		i++;

		i++;



	next:

		if (!threadgroup)

		if (!threadgroup)

			break;

			break;

	} while_each_thread(leader, tsk);

	} while_each_thread(leader, tsk);
@@ -3188,11 +3188,9 @@ css_next_descendant_post(struct cgroup_subsys_state *pos, 




	WARN_ON_ONCE(!rcu_read_lock_held());

	WARN_ON_ONCE(!rcu_read_lock_held());





	/* if first iteration, visit the leftmost descendant */

	/* if first iteration, visit leftmost descendant which may be @root */

	if (!pos) {

	if (!pos)

		next = css_leftmost_descendant(root);

		return css_leftmost_descendant(root);

		return next != root ? next : NULL;

	}





	/* if we visited @root, we're done */

	/* if we visited @root, we're done */

	if (pos == root)

	if (pos == root)