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author | Eric W. Biederman <ebiederm@xmission.com> | 2020-07-01 14:30:06 +0200 |
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committer | Eric W. Biederman <ebiederm@xmission.com> | 2020-07-07 18:58:17 +0200 |
commit | 38fd525a4c61e7ecdc9ad4dcbf7b767d0a007962 (patch) | |
tree | 1f255a978951c7c7464626f5de640d6ad5a420ac /kernel/exit.c | |
parent | umd: Track user space drivers with struct pid (diff) | |
download | linux-38fd525a4c61e7ecdc9ad4dcbf7b767d0a007962.tar.xz linux-38fd525a4c61e7ecdc9ad4dcbf7b767d0a007962.zip |
exit: Factor thread_group_exited out of pidfd_poll
Create an independent helper thread_group_exited which returns true
when all threads have passed exit_notify in do_exit. AKA all of the
threads are at least zombies and might be dead or completely gone.
Create this helper by taking the logic out of pidfd_poll where it is
already tested, and adding a READ_ONCE on the read of
task->exit_state.
I will be changing the user mode driver code to use this same logic
to know when a user mode driver needs to be restarted.
Place the new helper thread_group_exited in kernel/exit.c and
EXPORT it so it can be used by modules.
Link: https://lkml.kernel.org/r/20200702164140.4468-13-ebiederm@xmission.com
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r-- | kernel/exit.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index d3294b611df1..dee246c0866f 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1713,6 +1713,30 @@ 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); + __weak void abort(void) { BUG(); |