Commit 99fe36ba authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
Browse files

cgroup/cpuset: Improve temporary cpumasks handling 



The limitation that update_parent_subparts_cpumask() can only use
addmask & delmask in the given tmp cpumasks is fragile and may lead to
unexpected error.

Fix this problem by allocating/freeing a struct tmpmasks in
update_cpumask() to avoid reusing the cpumasks in trial_cs.

With this change, we can move the update_tasks_cpumask() for the
parent and update_sibling_cpumasks() for the sibling to inside
update_parent_subparts_cpumask().

Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent a86ce680

kernel/cgroup/cpuset.c

+13 −29
Original line number Diff line number Diff line
@@ -1277,6 +1277,8 @@ enum subparts_cmd { 


static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,

		       int turning_on);

static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,

				    struct tmpmasks *tmp);



/*

 * Update partition exclusive flag
@@ -1447,7 +1449,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 
		adding = cpumask_andnot(tmp->addmask, tmp->addmask,

					parent->subparts_cpus);

		/*

		 * Empty cpumask is not allewed

		 * Empty cpumask is not allowed

		 */

		if (cpumask_empty(newmask)) {

			part_error = PERR_CPUSEMPTY;
@@ -1567,8 +1569,11 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, 


	spin_unlock_irq(&callback_lock);



	if (adding || deleting)

	if (adding || deleting) {

		update_tasks_cpumask(parent, tmp->addmask);

		if (parent->child_ecpus_count)

			update_sibling_cpumasks(parent, cs, tmp);

	}



	/*

	 * For partcmd_update without newmask, it is being called from
@@ -1842,18 +1847,8 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, 
	if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))

		return 0;



#ifdef CONFIG_CPUMASK_OFFSTACK

	/*

	 * Use the cpumasks in trialcs for tmpmasks when they are pointers

	 * to allocated cpumasks.

	 *

	 * Note that update_parent_subparts_cpumask() uses only addmask &

	 * delmask, but not new_cpus.

	 */

	tmp.addmask  = trialcs->subparts_cpus;

	tmp.delmask  = trialcs->effective_cpus;

	tmp.new_cpus = NULL;

#endif

	if (alloc_cpumasks(NULL, &tmp))

		return -ENOMEM;



	retval = validate_change(cs, trialcs);
@@ -1882,7 +1877,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, 
		retval = 0;

	}

	if (retval < 0)

		return retval;

		goto out_free;



	if (cs->partition_root_state) {

		if (invalidate)
@@ -1917,11 +1912,6 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, 
	}

	spin_unlock_irq(&callback_lock);



#ifdef CONFIG_CPUMASK_OFFSTACK

	/* Now trialcs->cpus_allowed is available */

	tmp.new_cpus = trialcs->cpus_allowed;

#endif



	/* effective_cpus will be updated here */

	update_cpumasks_hier(cs, &tmp, false);
@@ -1938,6 +1928,8 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, 
		/* Update CS_SCHED_LOAD_BALANCE and/or sched_domains */

		update_partition_sd_lb(cs, old_prs);

	}

out_free:

	free_cpumasks(NULL, &tmp);

	return 0;

}
@@ -2346,13 +2338,11 @@ static int update_prstate(struct cpuset *cs, int new_prs) 


		err = update_parent_subparts_cpumask(cs, partcmd_enable,

						     NULL, &tmpmask);

		if (err)

			goto out;

	} else if (old_prs && new_prs) {

		/*

		 * A change in load balance state only, no change in cpumasks.

		 */

		goto out;

		;

	} else {

		/*

		 * Switching back to member is always allowed even if it
@@ -2372,12 +2362,6 @@ static int update_prstate(struct cpuset *cs, int new_prs) 
			spin_unlock_irq(&callback_lock);

		}

	}



	update_tasks_cpumask(parent, tmpmask.new_cpus);



	if (parent->child_ecpus_count)

		update_sibling_cpumasks(parent, cs, &tmpmask);



out:

	/*

	 * Make partition invalid & disable CS_CPU_EXCLUSIVE if an error