free_task(tsk);
}
+static int pidfd_release(struct inode *inode, struct file *file)
+{
+ struct pid *pid = file->private_data;
+
+ file->private_data = NULL;
+ put_pid(pid);
+ return 0;
+}
+
+#ifdef CONFIG_PROC_FS
+static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
+{
+ struct pid_namespace *ns = proc_pid_ns(file_inode(m->file));
+ struct pid *pid = f->private_data;
+
+ seq_put_decimal_ull(m, "Pid:\t", pid_nr_ns(pid, ns));
+ seq_putc(m, '\n');
+}
+#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
+};
+
+/**
+ * pidfd_create() - Create a new pid file descriptor.
+ *
+ * @pid: struct pid that the pidfd will reference
+ *
+ * This creates a new pid file descriptor with the O_CLOEXEC flag set.
+ *
+ * Note, that this function can only be called after the fd table has
+ * been unshared to avoid leaking the pidfd to the new process.
+ *
+ * Return: On success, a cloexec pidfd is returned.
+ * On error, a negative errno number will be returned.
+ */
+static int pidfd_create(struct pid *pid)
+{
+ int fd;
+
+ fd = anon_inode_getfd("[pidfd]", &pidfd_fops, get_pid(pid),
+ O_RDWR | O_CLOEXEC);
+ if (fd < 0)
+ put_pid(pid);
+
+ return fd;
+}
+
+ static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
+ {
+ /* Skip if kernel thread */
+ if (!tsk->mm)
+ return;
+
+ /* Skip if spawning a thread or using vfork */
+ if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
+ return;
+
+ /* We need to synchronize with __set_oom_adj */
+ mutex_lock(&oom_adj_mutex);
+ set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
+ /* Update the values in case they were changed after copy_signal */
+ tsk->signal->oom_score_adj = current->signal->oom_score_adj;
+ tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
+ mutex_unlock(&oom_adj_mutex);
+ }
+
/*
* This creates a new process as a copy of the old one,
* but does not actually start it yet.
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