kill PT_ATTACHED

Since the patch

	"Fix ptrace_attach()/ptrace_traceme()/de_thread() race"
	commit f5b40e363ad6041a96e3da32281d8faa191597b9

we set PT_ATTACHED and change child->parent "atomically" wrt task_list lock.

This means we can remove the checks like "PT_ATTACHED && ->parent != ptracer"
which were needed to catch the "ptrace attach is in progress" case.  We can
also remove the flag itself since nobody else uses it.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 5 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 5d30ff561847..6d6d1ab39e7e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1556,11 +1556,6 @@ static inline int may_ptrace_stop(void)
 {
         if (!likely(current->ptrace & PT_PTRACED))
                 return 0;
-
-        if (unlikely(current->parent == current->real_parent &&
-                    (current->ptrace & PT_ATTACHED)))
-                return 0;
-
         /*
          * Are we in the middle of do_coredump?
          * If so and our tracer is also part of the coredump stopping