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Merge branch 'for-3.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

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Pull cgroup fixes from Tejun Heo:
 "This pull request includes Alban's patch to disallow '\n' in cgroup
  names.

  Two other patches from Li to fix a possible oops when cgroup
  destruction races against other file operations and one from Vivek to
  fix a unified hierarchy devel behavior"

* 'for-3.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: check cgroup liveliness before unbreaking kernfs
  cgroup: delay the clearing of cgrp->kn->priv
  cgroup: Display legacy cgroup files on default hierarchy
  cgroup: reject cgroup names with '\n'
This commit is contained in:
Linus Torvalds 2014-09-07 20:20:16 -07:00
commit d030671f3f
1 changed files with 33 additions and 14 deletions
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47
kernel/cgroup.c
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@ -1035,6 +1035,11 @@ static void cgroup_get(struct cgroup *cgrp)
css_get(&cgrp->self);
}
static bool cgroup_tryget(struct cgroup *cgrp)
{
return css_tryget(&cgrp->self);
}
static void cgroup_put(struct cgroup *cgrp)
{
css_put(&cgrp->self);
@ -1147,7 +1152,8 @@ static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn)
* protection against removal. Ensure @cgrp stays accessible and
* break the active_ref protection.
*/
cgroup_get(cgrp);
if (!cgroup_tryget(cgrp))
return NULL;
kernfs_break_active_protection(kn);
mutex_lock(&cgroup_mutex);
@ -3271,8 +3277,17 @@ int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
{
struct cftype *cft;
for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
cft->flags |= __CFTYPE_NOT_ON_DFL;
/*
* If legacy_flies_on_dfl, we want to show the legacy files on the
* dfl hierarchy but iff the target subsystem hasn't been updated
* for the dfl hierarchy yet.
*/
if (!cgroup_legacy_files_on_dfl ||
ss->dfl_cftypes != ss->legacy_cftypes) {
for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
cft->flags |= __CFTYPE_NOT_ON_DFL;
}
return cgroup_add_cftypes(ss, cfts);
}
@ -4387,6 +4402,15 @@ static void css_release_work_fn(struct work_struct *work)
/* cgroup release path */
cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
cgrp->id = -1;
/*
* There are two control paths which try to determine
* cgroup from dentry without going through kernfs -
* cgroupstats_build() and css_tryget_online_from_dir().
* Those are supported by RCU protecting clearing of
* cgrp->kn->priv backpointer.
*/
RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL);
}
mutex_unlock(&cgroup_mutex);
@ -4543,6 +4567,11 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
struct cftype *base_files;
int ssid, ret;
/* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable.
*/
if (strchr(name, '\n'))
return -EINVAL;
parent = cgroup_kn_lock_live(parent_kn);
if (!parent)
return -ENODEV;
@ -4820,16 +4849,6 @@ static int cgroup_rmdir(struct kernfs_node *kn)
cgroup_kn_unlock(kn);
/*
* There are two control paths which try to determine cgroup from
* dentry without going through kernfs - cgroupstats_build() and
* css_tryget_online_from_dir(). Those are supported by RCU
* protecting clearing of cgrp->kn->priv backpointer, which should
* happen after all files under it have been removed.
*/
if (!ret)
RCU_INIT_POINTER(*(void __rcu __force **)&kn->priv, NULL);
cgroup_put(cgrp);
return ret;
}
@ -5416,7 +5435,7 @@ struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
/*
* This path doesn't originate from kernfs and @kn could already
* have been or be removed at any point. @kn->priv is RCU
* protected for this access. See cgroup_rmdir() for details.
* protected for this access. See css_release_work_fn() for details.
*/
cgrp = rcu_dereference(kn->priv);
if (cgrp)