Commit 7d80fea4 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-3.10-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 

Pull cgroup fixes from Tejun Heo:

 - Fix for yet another xattr bug which may lead to NULL deref.

 - A subtle bug in for_each_descendant_pre().  This bug requires quite
   specific conditions to trigger and isn't too likely to actually
   happen in the wild, but maybe that just makes it that much more
   nastier.

 - A warning message added for silly cgroup re-mount (not -o remount,
   but unmount followed by mount) behavior.

* 'for-3.10-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: warn about mismatching options of a new mount of an existing hierarchy
  cgroup: fix a subtle bug in descendant pre-order walk
  cgroup: initialize xattr before calling d_instantiate()
parents 338e33ac 2a0ff3fb

include/linux/cgroup.h

+1 −1
Original line number Diff line number Diff line
@@ -707,7 +707,7 @@ struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos); 
 *

 * If a subsystem synchronizes against the parent in its ->css_online() and

 * before starting iterating, and synchronizes against @pos on each

 * iteration, any descendant cgroup which finished ->css_offline() is

 * iteration, any descendant cgroup which finished ->css_online() is

 * guaranteed to be visible in the future iterations.

 *

 * In other words, the following guarantees that a descendant can't escape

kernel/cgroup.c

+16 −15
Original line number Diff line number Diff line
@@ -1686,11 +1686,14 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, 
		 */

		cgroup_drop_root(opts.new_root);



		if (((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) &&

		    root->flags != opts.flags) {

		if (root->flags != opts.flags) {

			if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) {

				pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n");

				ret = -EINVAL;

				goto drop_new_super;

			} else {

				pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n");

			}

		}



		/* no subsys rebinding, so refcounts don't change */
@@ -2699,13 +2702,14 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, 
		goto out;

	}



	mode = cgroup_file_mode(cft);

	error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb);

	if (!error) {

	cfe->type = (void *)cft;

	cfe->dentry = dentry;

	dentry->d_fsdata = cfe;

	simple_xattrs_init(&cfe->xattrs);



	mode = cgroup_file_mode(cft);

	error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb);

	if (!error) {

		list_add_tail(&cfe->node, &parent->files);

		cfe = NULL;

	}
@@ -2953,11 +2957,8 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, 
	WARN_ON_ONCE(!rcu_read_lock_held());



	/* if first iteration, pretend we just visited @cgroup */

	if (!pos) {

		if (list_empty(&cgroup->children))

			return NULL;

	if (!pos)

		pos = cgroup;

	}



	/* visit the first child if exists */

	next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling);
@@ -2965,14 +2966,14 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, 
		return next;



	/* no child, visit my or the closest ancestor's next sibling */

	do {

	while (pos != cgroup) {

		next = list_entry_rcu(pos->sibling.next, struct cgroup,

				      sibling);

		if (&next->sibling != &pos->parent->children)

			return next;



		pos = pos->parent;

	} while (pos != cgroup);

	}



	return NULL;

}

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