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-rw-r--r--kernel/cgroup.c32
1 files changed, 17 insertions, 15 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ea94984a3895..87441fc75663 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -795,28 +795,15 @@ static struct inode *cgroup_new_inode(mode_t mode, struct super_block *sb)
static int cgroup_call_pre_destroy(struct cgroup *cgrp)
{
struct cgroup_subsys *ss;
- struct cgroup_event *event, *tmp;
int ret = 0;
for_each_subsys(cgrp->root, ss)
if (ss->pre_destroy) {
ret = ss->pre_destroy(ss, cgrp);
if (ret)
- goto out;
+ break;
}
- /*
- * Unregister events and notify userspace.
- */
- spin_lock(&cgrp->event_list_lock);
- list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) {
- list_del(&event->list);
- eventfd_signal(event->eventfd, 1);
- schedule_work(&event->remove);
- }
- spin_unlock(&cgrp->event_list_lock);
-
-out:
return ret;
}
@@ -3006,7 +2993,6 @@ static void cgroup_event_remove(struct work_struct *work)
event->cft->unregister_event(cgrp, event->cft, event->eventfd);
eventfd_ctx_put(event->eventfd);
- remove_wait_queue(event->wqh, &event->wait);
kfree(event);
}
@@ -3024,6 +3010,7 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode,
unsigned long flags = (unsigned long)key;
if (flags & POLLHUP) {
+ remove_wait_queue_locked(event->wqh, &event->wait);
spin_lock(&cgrp->event_list_lock);
list_del(&event->list);
spin_unlock(&cgrp->event_list_lock);
@@ -3472,6 +3459,7 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
struct dentry *d;
struct cgroup *parent;
DEFINE_WAIT(wait);
+ struct cgroup_event *event, *tmp;
int ret;
/* the vfs holds both inode->i_mutex already */
@@ -3555,6 +3543,20 @@ again:
set_bit(CGRP_RELEASABLE, &parent->flags);
check_for_release(parent);
+ /*
+ * Unregister events and notify userspace.
+ * Notify userspace about cgroup removing only after rmdir of cgroup
+ * directory to avoid race between userspace and kernelspace
+ */
+ spin_lock(&cgrp->event_list_lock);
+ list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) {
+ list_del(&event->list);
+ remove_wait_queue(event->wqh, &event->wait);
+ eventfd_signal(event->eventfd, 1);
+ schedule_work(&event->remove);
+ }
+ spin_unlock(&cgrp->event_list_lock);
+
mutex_unlock(&cgroup_mutex);
return 0;
}