diff options
Diffstat (limited to 'kernel/pid.c')
| -rw-r--r-- | kernel/pid.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/kernel/pid.c b/kernel/pid.c index c835b844aca7..6d5d0a5bda82 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -363,6 +363,25 @@ void change_pid(struct task_struct *task, enum pid_type type, attach_pid(task, type); } +void exchange_tids(struct task_struct *left, struct task_struct *right) +{ + struct pid *pid1 = left->thread_pid; + struct pid *pid2 = right->thread_pid; + struct hlist_head *head1 = &pid1->tasks[PIDTYPE_PID]; + struct hlist_head *head2 = &pid2->tasks[PIDTYPE_PID]; + + /* Swap the single entry tid lists */ + hlists_swap_heads_rcu(head1, head2); + + /* Swap the per task_struct pid */ + rcu_assign_pointer(left->thread_pid, pid2); + rcu_assign_pointer(right->thread_pid, pid1); + + /* Swap the cached value */ + WRITE_ONCE(left->pid, pid_nr(pid2)); + WRITE_ONCE(right->pid, pid_nr(pid1)); +} + /* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */ void transfer_pid(struct task_struct *old, struct task_struct *new, enum pid_type type) |