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workqueue: ensure attrs changes are properly synchronized

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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: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Lai Jiangshan 2015-05-19 18:03:48 +08:00 committed by Tejun Heo
parent a0111cf671
commit d4d3e25797
1 changed files with 21 additions and 9 deletions
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30
kernel/workqueue.c
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@ -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_attrs *attrs;
int ret;
int ret = -ENOMEM;
apply_wqattrs_lock();
attrs = wq_sysfs_prep_attrs(wq);
if (!attrs)
return -ENOMEM;
goto out_unlock;
if (sscanf(buf, "%d", &attrs->nice) == 1 &&
attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE)
ret = apply_workqueue_attrs(wq, attrs);
ret = apply_workqueue_attrs_locked(wq, attrs);
else
ret = -EINVAL;
out_unlock:
apply_wqattrs_unlock();
free_workqueue_attrs(attrs);
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_attrs *attrs;
int ret;
int ret = -ENOMEM;
apply_wqattrs_lock();
attrs = wq_sysfs_prep_attrs(wq);
if (!attrs)
return -ENOMEM;
goto out_unlock;
ret = cpumask_parse(buf, attrs->cpumask);
if (!ret)
ret = apply_workqueue_attrs(wq, attrs);
ret = apply_workqueue_attrs_locked(wq, attrs);
out_unlock:
apply_wqattrs_unlock();
free_workqueue_attrs(attrs);
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_attrs *attrs;
int v, ret;
int v, ret = -ENOMEM;
apply_wqattrs_lock();
attrs = wq_sysfs_prep_attrs(wq);
if (!attrs)
return -ENOMEM;
goto out_unlock;
ret = -EINVAL;
if (sscanf(buf, "%d", &v) == 1) {
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);
return ret ?: count;
}