Date:2010-05-07 08:57:00 (12 years 4 months ago)
Author:Li Zefan
Commit:0341509fdfc9519f7de6aabc5dd23217cef72b73
Message:blk-cgroup: Fix an RCU warning in blkiocg_create()

with CONFIG_PROVE_RCU=y, a warning can be triggered:

# mount -t cgroup -o blkio xxx /mnt
# mkdir /mnt/subgroup

...
kernel/cgroup.c:4442 invoked rcu_dereference_check() without protection!
...

To fix this, we avoid caling css_depth() here, which is a bit simpler
than the original code.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Files: block/blk-cgroup.c (1 diff)

Change Details

block/blk-cgroup.c
286286static struct cgroup_subsys_state *
287287blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
288288{
289    struct blkio_cgroup *blkcg, *parent_blkcg;
289    struct blkio_cgroup *blkcg;
290    struct cgroup *parent = cgroup->parent;
290291
291    if (!cgroup->parent) {
292    if (!parent) {
292293        blkcg = &blkio_root_cgroup;
293294        goto done;
294295    }
295296
296297    /* Currently we do not support hierarchy deeper than two level (0,1) */
297    parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent);
298    if (css_depth(&parent_blkcg->css) > 0)
298    if (parent != cgroup->top_cgroup)
299299        return ERR_PTR(-EINVAL);
300300
301301    blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);

Archive Download the corresponding diff file



interactive