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| author | Oleg Nesterov <oleg@redhat.com> | 2024-02-02 14:12:26 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-02-02 14:57:53 +0100 |
| commit | 43f0df54c96fa5abcab9df8649c1e52119bf0238 (patch) | |
| tree | 3233889920853f7ea8355d41d33f084dad59f799 /kernel/fork.c | |
| parent | 64bef697d33b75fc06c5789b3f8108680271529f (diff) | |
| download | lwn-43f0df54c96fa5abcab9df8649c1e52119bf0238.tar.gz lwn-43f0df54c96fa5abcab9df8649c1e52119bf0238.zip | |
pidfd_poll: report POLLHUP when pid_task() == NULL
Add another wake_up_all(wait_pidfd) into __change_pid() and change
pidfd_poll() to include EPOLLHUP if task == NULL.
This allows to wait until the target process/thread is reaped.
TODO: change do_notify_pidfd() to use the keyed wakeups.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20240202131226.GA26018@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 22 |
1 files changed, 7 insertions, 15 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 1a9b91055916..aa08193d124f 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2071,20 +2071,6 @@ static void pidfd_show_fdinfo(struct seq_file *m, struct file *f) } #endif -static bool pidfd_task_exited(struct pid *pid, bool thread) -{ - struct task_struct *task; - bool exited; - - rcu_read_lock(); - task = pid_task(pid, PIDTYPE_PID); - exited = !task || - (READ_ONCE(task->exit_state) && (thread || thread_group_empty(task))); - rcu_read_unlock(); - - return exited; -} - /* * Poll support for process exit notification. */ @@ -2092,6 +2078,7 @@ static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts) { struct pid *pid = file->private_data; bool thread = file->f_flags & PIDFD_THREAD; + struct task_struct *task; __poll_t poll_flags = 0; poll_wait(file, &pid->wait_pidfd, pts); @@ -2099,8 +2086,13 @@ static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts) * Depending on PIDFD_THREAD, inform pollers when the thread * or the whole thread-group exits. */ - if (pidfd_task_exited(pid, thread)) + rcu_read_lock(); + task = pid_task(pid, PIDTYPE_PID); + if (!task) + poll_flags = EPOLLIN | EPOLLRDNORM | EPOLLHUP; + else if (task->exit_state && (thread || thread_group_empty(task))) poll_flags = EPOLLIN | EPOLLRDNORM; + rcu_read_unlock(); return poll_flags; } |