pidfd: exit: kill the no longer used thread_group_exited()

It was used by pidfd_poll() but now it has no callers.

If it finally finds a modular user we can revert this change, but note
that the comment above this helper and the changelog in 38fd525a4c61
("exit: Factor thread_group_exited out of pidfd_poll") are not accurate,
thread_group_exited() won't return true if all other threads have passed
exit_notify() and are zombies, it returns true only when all other threads
are completely gone. Not to mention that it can only work if the task
identified by @pid is a thread-group leader.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20240205174347.GA31461@redhat.com
Reviewed-by: Tycho Andersen <tandersen@netflix.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 4b7664c56208f9db855c527cd6daff672454d106..0a0e23c45406fe477a8c32534326bde451e4a45a 100644 (file)
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -735,8 +735,6 @@ static inline int thread_group_empty(struct task_struct *p)
 #define delay_group_leader(p) \
                (thread_group_leader(p) && !thread_group_empty(p))
 
-extern bool thread_group_exited(struct pid *pid);
-
 extern struct sighand_struct *__lock_task_sighand(struct task_struct *task,
                                                        unsigned long *flags);
 

diff --git a/kernel/exit.c b/kernel/exit.c
index c038d10dfb38685472f4d0b7efaa1865f75350cf..0e2f5dec91fb1f2caf3158e7302e16c8b97439c3 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1900,30 +1900,6 @@ Efault:
 }
 #endif
 
-/**
- * thread_group_exited - check that a thread group has exited
- * @pid: tgid of thread group to be checked.
- *
- * Test if the thread group represented by tgid has exited (all
- * threads are zombies, dead or completely gone).
- *
- * Return: true if the thread group has exited. false otherwise.
- */
-bool thread_group_exited(struct pid *pid)
-{
-       struct task_struct *task;
-       bool exited;
-
-       rcu_read_lock();
-       task = pid_task(pid, PIDTYPE_PID);
-       exited = !task ||
-               (READ_ONCE(task->exit_state) && thread_group_empty(task));
-       rcu_read_unlock();
-
-       return exited;
-}
-EXPORT_SYMBOL(thread_group_exited);
-
 /*
  * This needs to be __function_aligned as GCC implicitly makes any
  * implementation of abort() cold and drops alignment specified by