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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: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Oleg Nesterov 2011-06-23 19:06:50 +02:00
parent 53c8f9f199
commit 45cdf5cc07
2 changed files with 13 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
include/linux/tracehook.h
View File

@ -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

21
kernel/exit.c
View File

@ -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;