ptrace: do_wait(traced_leader_killed_by_mt_exec) can block forever

[linux-2.6-block.git] / fs / exec.c

diff --git a/fs/exec.c b/fs/exec.c
index b08367abf30e52062dcb0ce4058b06289198be41..d219541db06c7ad6e6f5a0991e30551ac50ad1e0 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -967,6 +967,14 @@ static int de_thread(struct task_struct *tsk)
 
                BUG_ON(leader->exit_state != EXIT_ZOMBIE);
                leader->exit_state = EXIT_DEAD;
+
+               /*
+                * We are going to release_task()->ptrace_unlink() silently,
+                * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
+                * the tracer wont't block again waiting for this thread.
+                */
+               if (unlikely(leader->ptrace))
+                       __wake_up_parent(leader, leader->parent);
                write_unlock_irq(&tasklist_lock);
 
                release_task(leader);