Commit 45cdf5cc authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

kill tracehook_notify_death() 



Kill tracehook_notify_death(), reimplement the logic in its caller,
exit_notify().

Also, change the exec_id's check to use thread_group_leader() instead
of task_detached(), this is more clear. This logic only applies to
the exiting leader, a sub-thread must never change its exit_signal.

Note: when the traced group leader exits the exit_signal-or-SIGCHLD
logic looks really strange:

	- we notify the tracer even if !thread_group_empty() but
	   do_wait(WEXITED) can't work until all threads exit

	- if the tracer is real_parent, it is not clear why can't
	  we use ->exit_signal event if !thread_group_empty()

-v2: do not try to fix the 2nd oddity to avoid the subtle behavior
     change mixed with reorganization, suggested by Tejun.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarTejun Heo <tj@kernel.org>
parent 53c8f9f1

include/linux/tracehook.h

+0 −34
Original line number Diff line number Diff line
@@ -152,40 +152,6 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info, 
		ptrace_notify(SIGTRAP);

}



#define DEATH_REAP			-1

#define DEATH_DELAYED_GROUP_LEADER	-2



/**

 * tracehook_notify_death - task is dead, ready to notify parent

 * @task:		@current task now exiting

 * @death_cookie:	value to pass to tracehook_report_death()

 * @group_dead:		nonzero if this was the last thread in the group to die

 *

 * A return value >= 0 means call do_notify_parent() with that signal

 * number.  Negative return value can be %DEATH_REAP to self-reap right

 * now, or %DEATH_DELAYED_GROUP_LEADER to a zombie without notifying our

 * parent.  Note that a return value of 0 means a do_notify_parent() call

 * that sends no signal, but still wakes up a parent blocked in wait*().

 *

 * Called with write_lock_irq(&tasklist_lock) held.

 */

static inline int tracehook_notify_death(struct task_struct *task,

					 void **death_cookie, int group_dead)

{

	if (task_detached(task))

		return task->ptrace ? SIGCHLD : DEATH_REAP;



	/*

	 * If something other than our normal parent is ptracing us, then

	 * send it a SIGCHLD instead of honoring exit_signal.  exit_signal

	 * only has special meaning to our real parent.

	 */

	if (thread_group_empty(task) && !ptrace_reparented(task))

		return task->exit_signal;



	return task->ptrace ? SIGCHLD : DEATH_DELAYED_GROUP_LEADER;

}



#ifdef TIF_NOTIFY_RESUME

/**

 * set_notify_resume - cause tracehook_notify_resume() to be called

kernel/exit.c

+13 −8
Original line number Diff line number Diff line
@@ -819,9 +819,7 @@ static void forget_original_parent(struct task_struct *father) 
 */

static void exit_notify(struct task_struct *tsk, int group_dead)

{

	int signal;

	bool autoreap;

	void *cookie;



	/*

	 * This does two things:
@@ -852,16 +850,23 @@ static void exit_notify(struct task_struct *tsk, int group_dead) 
	 * we have changed execution domain as these two values started

	 * the same after a fork.

	 */

	if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) &&

	if (thread_group_leader(tsk) && tsk->exit_signal != SIGCHLD &&

	    (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||

	     tsk->self_exec_id != tsk->parent_exec_id))

		tsk->exit_signal = SIGCHLD;



	signal = tracehook_notify_death(tsk, &cookie, group_dead);

	if (signal >= 0)

		autoreap = do_notify_parent(tsk, signal);

	else

		autoreap = (signal == DEATH_REAP);

	if (unlikely(tsk->ptrace)) {

		int sig = thread_group_leader(tsk) &&

				thread_group_empty(tsk) &&

				!ptrace_reparented(tsk) ?

			tsk->exit_signal : SIGCHLD;

		autoreap = do_notify_parent(tsk, sig);

	} else if (thread_group_leader(tsk)) {

		autoreap = thread_group_empty(tsk) &&

			do_notify_parent(tsk, tsk->exit_signal);

	} else {

		autoreap = true;

	}



	tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;

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