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cgroup: fix the retry path of cgroup_mount() 

If we hit the retry path, we'll call parse_cgroupfs_options() again,
but the string we pass to it has been modified by the previous call
to this function.

This bug can be observed by:

  # mount -t cgroup -o name=foo,cpuset xxx /mnt && umount /mnt && \
    mount -t cgroup -o name=foo,cpuset xxx /mnt
  mount: wrong fs type, bad option, bad superblock on xxx,
         missing codepage or helper program, or other error
  ...

The second mount passed "name=foo,cpuset" to the parser, and then it
hit the retry path and call the parser again, but this time the string
passed to the parser is "name=foo".

To fix this, we avoid calling parse_cgroupfs_options() again in this
case.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Li Zefan 2014-04-17 13:53:08 +08:00 committed by Tejun Heo
parent c9eaa447e7
commit e37a06f109
1 changed files with 4 additions and 4 deletions
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8
kernel/cgroup.c
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@ -1495,7 +1495,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
*/
if (!use_task_css_set_links)
cgroup_enable_task_cg_lists();
retry:
mutex_lock(&cgroup_tree_mutex);
mutex_lock(&cgroup_mutex);
@ -1503,7 +1503,7 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
ret = parse_cgroupfs_options(data, &opts);
if (ret)
goto out_unlock;
retry:
/* look for a matching existing root */
if (!opts.subsys_mask && !opts.none && !opts.name) {
cgrp_dfl_root_visible = true;
@ -1562,9 +1562,9 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
if (!atomic_inc_not_zero(&root->cgrp.refcnt)) {
mutex_unlock(&cgroup_mutex);
mutex_unlock(&cgroup_tree_mutex);
kfree(opts.release_agent);
kfree(opts.name);
msleep(10);
mutex_lock(&cgroup_tree_mutex);
mutex_lock(&cgroup_mutex);
goto retry;
}