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

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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>
This commit is contained in:
Oleg Nesterov 2014-04-07 15:38:46 -07:00 committed by Linus Torvalds
parent b3ab03160d
commit ad86622b47
2 changed files with 4 additions and 4 deletions
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4
fs/proc/array.c
View File

@ -138,8 +138,8 @@ static const char * const task_state_array[] = {
"D (disk sleep)", /* 2 */
"T (stopped)", /* 4 */
"t (tracing stop)", /* 8 */
"Z (zombie)", /* 16 */
"X (dead)", /* 32 */
"X (dead)", /* 16 */
"Z (zombie)", /* 32 */
};
static inline const char *get_task_state(struct task_struct *tsk)

4
include/linux/sched.h
View File

@ -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