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Commit d4d3e257 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Tejun Heo
Browse files

workqueue: ensure attrs changes are properly synchronized 



Current modification to attrs via sysfs is not fully synchronized.

Process A (change cpumask)      | Process B (change numa affinity)
wq_cpumask_store()              |
  wq_sysfs_prep_attrs()         |
                                | apply_workqueue_attrs()
  apply_workqueue_attrs()       |

It results that the Process B's operation is totally reverted
without any notification, it is a buggy behavior.  So this patch
moves wq_sysfs_prep_attrs() into the protection under wq_pool_mutex
to ensure attrs changes are properly synchronized.

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent a0111cf6

kernel/workqueue.c

+21 −9
Original line number Original line Diff line number Diff line
@@ -4954,18 +4954,22 @@ static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, 
{

{

	struct workqueue_struct *wq = dev_to_wq(dev);

	struct workqueue_struct *wq = dev_to_wq(dev);

	struct workqueue_attrs *attrs;

	struct workqueue_attrs *attrs;

	int ret;

	int ret = -ENOMEM;



	apply_wqattrs_lock();





	attrs = wq_sysfs_prep_attrs(wq);

	attrs = wq_sysfs_prep_attrs(wq);

	if (!attrs)

	if (!attrs)

		return -ENOMEM;

		goto out_unlock;





	if (sscanf(buf, "%d", &attrs->nice) == 1 &&

	if (sscanf(buf, "%d", &attrs->nice) == 1 &&

	    attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE)

	    attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE)

		ret = apply_workqueue_attrs(wq, attrs);

		ret = apply_workqueue_attrs_locked(wq, attrs);

	else

	else

		ret = -EINVAL;

		ret = -EINVAL;





out_unlock:

	apply_wqattrs_unlock();

	free_workqueue_attrs(attrs);

	free_workqueue_attrs(attrs);

	return ret ?: count;

	return ret ?: count;

}

}
@@ -4989,16 +4993,20 @@ static ssize_t wq_cpumask_store(struct device *dev, 
{

{

	struct workqueue_struct *wq = dev_to_wq(dev);

	struct workqueue_struct *wq = dev_to_wq(dev);

	struct workqueue_attrs *attrs;

	struct workqueue_attrs *attrs;

	int ret;

	int ret = -ENOMEM;



	apply_wqattrs_lock();





	attrs = wq_sysfs_prep_attrs(wq);

	attrs = wq_sysfs_prep_attrs(wq);

	if (!attrs)

	if (!attrs)

		return -ENOMEM;

		goto out_unlock;





	ret = cpumask_parse(buf, attrs->cpumask);

	ret = cpumask_parse(buf, attrs->cpumask);

	if (!ret)

	if (!ret)

		ret = apply_workqueue_attrs(wq, attrs);

		ret = apply_workqueue_attrs_locked(wq, attrs);





out_unlock:

	apply_wqattrs_unlock();

	free_workqueue_attrs(attrs);

	free_workqueue_attrs(attrs);

	return ret ?: count;

	return ret ?: count;

}

}
@@ -5022,18 +5030,22 @@ static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr, 
{

{

	struct workqueue_struct *wq = dev_to_wq(dev);

	struct workqueue_struct *wq = dev_to_wq(dev);

	struct workqueue_attrs *attrs;

	struct workqueue_attrs *attrs;

	int v, ret;

	int v, ret = -ENOMEM;



	apply_wqattrs_lock();





	attrs = wq_sysfs_prep_attrs(wq);

	attrs = wq_sysfs_prep_attrs(wq);

	if (!attrs)

	if (!attrs)

		return -ENOMEM;

		goto out_unlock;





	ret = -EINVAL;

	ret = -EINVAL;

	if (sscanf(buf, "%d", &v) == 1) {

	if (sscanf(buf, "%d", &v) == 1) {

		attrs->no_numa = !v;

		attrs->no_numa = !v;

		ret = apply_workqueue_attrs(wq, attrs);

		ret = apply_workqueue_attrs_locked(wq, attrs);

	}

	}





out_unlock:

	apply_wqattrs_unlock();

	free_workqueue_attrs(attrs);

	free_workqueue_attrs(attrs);

	return ret ?: count;

	return ret ?: count;

}

}