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-rw-r--r--kernel/fork.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index b4cba953040a..2cdf295b72c7 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1704,8 +1704,34 @@ static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
}
#endif
+/*
+ * Poll support for process exit notification.
+ */
+static unsigned int pidfd_poll(struct file *file, struct poll_table_struct *pts)
+{
+ struct task_struct *task;
+ struct pid *pid = file->private_data;
+ int poll_flags = 0;
+
+ poll_wait(file, &pid->wait_pidfd, pts);
+
+ rcu_read_lock();
+ task = pid_task(pid, PIDTYPE_PID);
+ /*
+ * Inform pollers only when the whole thread group exits.
+ * If the thread group leader exits before all other threads in the
+ * group, then poll(2) should block, similar to the wait(2) family.
+ */
+ if (!task || (task->exit_state && thread_group_empty(task)))
+ poll_flags = POLLIN | POLLRDNORM;
+ rcu_read_unlock();
+
+ return poll_flags;
+}
+
const struct file_operations pidfd_fops = {
.release = pidfd_release,
+ .poll = pidfd_poll,
#ifdef CONFIG_PROC_FS
.show_fdinfo = pidfd_show_fdinfo,
#endif