wait: swap EXIT_ZOMBIE and EXIT_DEAD to hide EXIT_TRACE from user-space

get_task_state() uses the most significant bit to report the state to
user-space, this means that EXIT_ZOMBIE->EXIT_TRACE->EXIT_DEAD transition
can be noticed via /proc as Z -> X -> Z change.  Note that this was
possible even before EXIT_TRACE was introduced.

This is not really bad but imho it make sense to hide EXIT_TRACE from
user-space completely.  So the patch simply swaps EXIT_ZOMBIE and
EXIT_DEAD, this way EXIT_TRACE will be seen as EXIT_ZOMBIE by user-space.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Michal Schmidt <mschmidt@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Lennart Poettering <lpoetter@redhat.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 7781de5e5e7b..075b3056c0c0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -210,8 +210,8 @@ print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq);
 #define __TASK_STOPPED          4
 #define __TASK_TRACED           8
 /* in tsk->exit_state */
-#define EXIT_ZOMBIE             16
-#define EXIT_DEAD               32
+#define EXIT_DEAD               16
+#define EXIT_ZOMBIE             32
 #define EXIT_TRACE              (EXIT_ZOMBIE | EXIT_DEAD)
 /* in tsk->state again */
 #define TASK_DEAD               64