Merge tag 'regmap-fix-v5.8-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux-2.6-microblaze.git] / kernel / pid.c

diff --git a/kernel/pid.c b/kernel/pid.c
index c835b84..f1496b7 100644 (file)
--- 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)
@@ -476,8 +495,7 @@ pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
        rcu_read_lock();
        if (!ns)
                ns = task_active_pid_ns(current);
-       if (likely(pid_alive(task)))
-               nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns);
+       nr = pid_nr_ns(rcu_dereference(*task_pid_ptr(task, type)), ns);
        rcu_read_unlock();
 
        return nr;