int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
unsigned long val, void *v)
{
- int ret;
+ int ret = NOTIFY_DONE;
- down_read(&nh->rwsem);
- ret = notifier_call_chain(&nh->head, val, v);
- up_read(&nh->rwsem);
+ /*
+ * We check the head outside the lock, but if this access is
+ * racy then it does not matter what the result of the test
+ * is, we re-check the list after having taken the lock anyway:
+ */
+ if (rcu_dereference(nh->head)) {
+ down_read(&nh->rwsem);
+ ret = notifier_call_chain(&nh->head, val, v);
+ up_read(&nh->rwsem);
+ }
return ret;
}
goto out;
if (pgid != pid) {
- struct task_struct *p;
+ struct task_struct *g =
+ find_task_by_pid_type(PIDTYPE_PGID, pgid);
- do_each_task_pid(pgid, PIDTYPE_PGID, p) {
- if (process_session(p) == process_session(group_leader))
- goto ok_pgid;
- } while_each_task_pid(pgid, PIDTYPE_PGID, p);
- goto out;
+ if (!g || process_session(g) != process_session(group_leader))
+ goto out;
}
-ok_pgid:
err = security_task_setpgid(p, pgid);
if (err)
goto out;