pidfd_poll: report POLLHUP when pid_task() == NULL

[linux-2.6-block.git] / kernel / fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index 1a9b910559169c2bec683948c74475dcd77a5048..aa08193d124f922188a096f4c20f1f01d698fee8 100644 (file)
--- 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;
 }