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-rw-r--r--include/linux/cgroup.h1
-rw-r--r--kernel/cgroup.c62
-rw-r--r--kernel/cgroup_freezer.c13
-rw-r--r--kernel/fork.c9
4 files changed, 35 insertions, 50 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index f8a030ced0c7..4cd1d0fd2542 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -34,7 +34,6 @@ extern int cgroup_lock_is_held(void);
extern bool cgroup_lock_live_group(struct cgroup *cgrp);
extern void cgroup_unlock(void);
extern void cgroup_fork(struct task_struct *p);
-extern void cgroup_fork_callbacks(struct task_struct *p);
extern void cgroup_post_fork(struct task_struct *p);
extern void cgroup_exit(struct task_struct *p, int run_callbacks);
extern int cgroupstats_build(struct cgroupstats *stats,
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 13774b3b39aa..b7a0171067ea 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4844,44 +4844,19 @@ void cgroup_fork(struct task_struct *child)
}
/**
- * cgroup_fork_callbacks - run fork callbacks
- * @child: the new task
- *
- * Called on a new task very soon before adding it to the
- * tasklist. No need to take any locks since no-one can
- * be operating on this task.
- */
-void cgroup_fork_callbacks(struct task_struct *child)
-{
- if (need_forkexit_callback) {
- int i;
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- struct cgroup_subsys *ss = subsys[i];
-
- /*
- * forkexit callbacks are only supported for
- * builtin subsystems.
- */
- if (!ss || ss->module)
- continue;
-
- if (ss->fork)
- ss->fork(child);
- }
- }
-}
-
-/**
* cgroup_post_fork - called on a new task after adding it to the task list
* @child: the task in question
*
- * Adds the task to the list running through its css_set if necessary.
- * Has to be after the task is visible on the task list in case we race
- * with the first call to cgroup_iter_start() - to guarantee that the
- * new task ends up on its list.
+ * Adds the task to the list running through its css_set if necessary and
+ * call the subsystem fork() callbacks. Has to be after the task is
+ * visible on the task list in case we race with the first call to
+ * cgroup_iter_start() - to guarantee that the new task ends up on its
+ * list.
*/
void cgroup_post_fork(struct task_struct *child)
{
+ int i;
+
/*
* use_task_css_set_links is set to 1 before we walk the tasklist
* under the tasklist_lock and we read it here after we added the child
@@ -4910,7 +4885,30 @@ void cgroup_post_fork(struct task_struct *child)
}
write_unlock(&css_set_lock);
}
+
+ /*
+ * Call ss->fork(). This must happen after @child is linked on
+ * css_set; otherwise, @child might change state between ->fork()
+ * and addition to css_set.
+ */
+ if (need_forkexit_callback) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+
+ /*
+ * fork/exit callbacks are supported only for
+ * builtin subsystems and we don't need further
+ * synchronization as they never go away.
+ */
+ if (!ss || ss->module)
+ continue;
+
+ if (ss->fork)
+ ss->fork(child);
+ }
+ }
}
+
/**
* cgroup_exit - detach cgroup from exiting task
* @tsk: pointer to task_struct of exiting process
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index b1724ce98981..12bfedb598c2 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -186,23 +186,15 @@ static void freezer_fork(struct task_struct *task)
{
struct freezer *freezer;
- /*
- * No lock is needed, since the task isn't on tasklist yet,
- * so it can't be moved to another cgroup, which means the
- * freezer won't be removed and will be valid during this
- * function call. Nevertheless, apply RCU read-side critical
- * section to suppress RCU lockdep false positives.
- */
rcu_read_lock();
freezer = task_freezer(task);
- rcu_read_unlock();
/*
* The root cgroup is non-freezable, so we can skip the
* following check.
*/
if (!freezer->css.cgroup->parent)
- return;
+ goto out;
spin_lock_irq(&freezer->lock);
BUG_ON(freezer->state == CGROUP_FROZEN);
@@ -210,7 +202,10 @@ static void freezer_fork(struct task_struct *task)
/* Locking avoids race with FREEZING -> THAWED transitions. */
if (freezer->state == CGROUP_FREEZING)
freeze_task(task);
+
spin_unlock_irq(&freezer->lock);
+out:
+ rcu_read_unlock();
}
/*
diff --git a/kernel/fork.c b/kernel/fork.c
index 8b20ab7d3aa2..acc4cb62f32f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1135,7 +1135,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
{
int retval;
struct task_struct *p;
- int cgroup_callbacks_done = 0;
if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
return ERR_PTR(-EINVAL);
@@ -1393,12 +1392,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
INIT_LIST_HEAD(&p->thread_group);
p->task_works = NULL;
- /* Now that the task is set up, run cgroup callbacks if
- * necessary. We need to run them before the task is visible
- * on the tasklist. */
- cgroup_fork_callbacks(p);
- cgroup_callbacks_done = 1;
-
/* Need tasklist lock for parent etc handling! */
write_lock_irq(&tasklist_lock);
@@ -1503,7 +1496,7 @@ bad_fork_cleanup_cgroup:
#endif
if (clone_flags & CLONE_THREAD)
threadgroup_change_end(current);
- cgroup_exit(p, cgroup_callbacks_done);
+ cgroup_exit(p, 0);
delayacct_tsk_free(p);
module_put(task_thread_info(p)->exec_domain->module);
bad_fork_cleanup_count: