Kill some obsolete sub-thread-ptrace stuff

There is a couple of subtle checks which were needed to handle ptracing from
the same thread group. This was deprecated a long ago, imho this code just
complicates the understanding.

And, the "->parent->signal->flags & SIGNAL_GROUP_EXIT" check in exit_notify()
is not right. SIGNAL_GROUP_EXIT can mean exec(), not exit_group(). This means
ptracer can lose a ptraced zombie on exec(). Minor problem, but still the bug.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 4 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index ef8156a6aad5..b27c01a66448 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1561,10 +1561,6 @@ static inline int may_ptrace_stop(void)
                     (current->ptrace & PT_ATTACHED)))
                 return 0;
 
-        if (unlikely(current->signal == current->parent->signal) &&
-            unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))
-                return 0;
-
         /*
          * Are we in the middle of do_coredump?
          * If so and our tracer is also part of the coredump stopping