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| author | Li Zefan <lizefan@huawei.com> | 2014-02-14 16:54:28 +0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2014-02-14 10:52:39 -0500 |
| commit | bad34660344f37db8b55ce8bc139bddc7d83af1b (patch) | |
| tree | 21fbb75b3761a8f9c6d902780209089d6f059fb4 /kernel/cgroup.c | |
| parent | 430af8ad9dad82d775d688155e1db1da385d3e7a (diff) | |
| download | lwn-bad34660344f37db8b55ce8bc139bddc7d83af1b.tar.gz lwn-bad34660344f37db8b55ce8bc139bddc7d83af1b.zip | |
cgroup: fix locking in cgroupstats_build()
css_set_lock has been converted to css_set_rwsem, and rwsem can't nest
inside rcu_read_lock.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 15dcae74b510..5606c0f08d95 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2995,6 +2995,8 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) kernfs_type(kn) != KERNFS_DIR) return -EINVAL; + mutex_lock(&cgroup_mutex); + /* * We aren't being called from kernfs and there's no guarantee on * @kn->priv's validity. For this and css_tryget_from_dir(), @@ -3002,10 +3004,12 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) */ rcu_read_lock(); cgrp = rcu_dereference(kn->priv); - if (!cgrp) { + if (!cgrp || cgroup_is_dead(cgrp)) { rcu_read_unlock(); + mutex_unlock(&cgroup_mutex); return -ENOENT; } + rcu_read_unlock(); css_task_iter_start(&cgrp->dummy_css, &it); while ((tsk = css_task_iter_next(&it))) { @@ -3030,7 +3034,7 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) } css_task_iter_end(&it); - rcu_read_unlock(); + mutex_unlock(&cgroup_mutex); return 0; } |