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authorLai Jiangshan <laijs@cn.fujitsu.com>2009-01-07 18:07:36 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-08 08:31:02 -0800
commit2019f634ce5904c19eba4e86f51b1a119a53a9f1 (patch)
tree040b8645c0627baa0f4e44113589b5a4894ea629
parentb12b533fa523e94e0cc9dc23274ae4f9439f1313 (diff)
cgroups: fix cgroup_iter_next() bug
We access res->cgroups without the task_lock(), so res->cgroups may be changed. it's unreliable, and "if (l == &res->cgroups->tasks)" may be false forever. We don't need add any lock for fixing this bug. we just access to struct css_set by struct cg_cgroup_link, not by struct task_struct. Since we hold css_set_lock, struct cg_cgroup_link is reliable. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Balbir Singh <balbir@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/cgroup.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index d7ab4ffd8fd..a391ab3bdfc 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1808,6 +1808,7 @@ struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
{
struct task_struct *res;
struct list_head *l = it->task;
+ struct cg_cgroup_link *link;
/* If the iterator cg is NULL, we have no tasks */
if (!it->cg_link)
@@ -1815,7 +1816,8 @@ struct task_struct *cgroup_iter_next(struct cgroup *cgrp,
res = list_entry(l, struct task_struct, cg_list);
/* Advance iterator to find next entry */
l = l->next;
- if (l == &res->cgroups->tasks) {
+ link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list);
+ if (l == &link->cg->tasks) {
/* We reached the end of this task list - move on to
* the next cg_cgroup_link */
cgroup_advance_iter(cgrp, it);