pids: document task_pgrp/task_session is not safe without tasklist/rcu

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / include / linux / sched.h

diff --git a/include/linux/sched.h b/include/linux/sched.h
index b47c94e7560b30f067a885e8ae7a96fb5ab59b4e..722dd313bf8ab149563789ff297333040df5efe0 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1489,6 +1489,11 @@ static inline struct pid *task_tgid(struct task_struct *task)
        return task->group_leader->pids[PIDTYPE_PID].pid;
 }
 
+/*
+ * Without tasklist or rcu lock it is not safe to dereference
+ * the result of task_pgrp/task_session even if task == current,
+ * we can race with another thread doing sys_setsid/sys_setpgid.
+ */
 static inline struct pid *task_pgrp(struct task_struct *task)
 {
        return task->group_leader->pids[PIDTYPE_PGID].pid;