[PATCH 0/8] kill task_detached() (Was: ptrace: kill detah tracehooks)

[Oleg Nesterov <oleg@redhat.com>]

Remove tracehook_notify_death(), and kill task_detached() logic.

IMHO, task_detached() is very strange and confusing. Sometimes it used
instead of !thread_group_leader() when the task is live. Sometimes it
is used to detect the EXIT_DEAD tasks (reparent_leader). Sometimes it
used after do_notify_parent() which sets ->exit_signal = -1 to signal
the caller it should set EXIT_DEAD.

Basically, this series does:

	- s/task_detached/thread_group_leader/ when the caller need
	  to know if it is the group_leader or not

	- s/task_detached/EXIT_DEAD/ when the caller needs to filter
	  out the EXIT_DEAD tasks

	- changes do_notify_parent() to return a boolean and converts
	  the callers from

	  	do_notify_parent(p);
	  	if (task_detached(p))
	  		// aha, do_notify_parent() changed ->exit_signal
	  		release_task(p)

	  to
		if (do_notify_parent(p))
			release_task(p)

	- kills the now unused task_detached()

	- makes task->exit_signal "const" and redefines thread_group_leader()
	  for micro-optimization.


 fs/exec.c                 |    1 +
 include/linux/sched.h     |   15 ++++-------
 include/linux/tracehook.h |   34 --------------------------
 kernel/exit.c             |   58 +++++++++++++++++++-------------------------
 kernel/ptrace.c           |   32 +++++++++++++-----------
 kernel/signal.c           |   16 ++++++------
 6 files changed, 57 insertions(+), 99 deletions(-)

Oleg.