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Merge branch 'ptrace' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc into ptrace

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This commit is contained in:
Oleg Nesterov 2011-04-07 20:44:11 +02:00
commit e46bc9b6fd
6 changed files with 445 additions and 183 deletions
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86
kernel/exit.c
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@ -1538,33 +1538,83 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
return 0;
}
if (likely(!ptrace) && unlikely(task_ptrace(p))) {
/*
* This child is hidden by ptrace.
* We aren't allowed to see it now, but eventually we will.
*/
wo->notask_error = 0;
return 0;
}
/* dead body doesn't have much to contribute */
if (p->exit_state == EXIT_DEAD)
return 0;
/*
* We don't reap group leaders with subthreads.
*/
if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))
return wait_task_zombie(wo, p);
/* slay zombie? */
if (p->exit_state == EXIT_ZOMBIE) {
/*
* A zombie ptracee is only visible to its ptracer.
* Notification and reaping will be cascaded to the real
* parent when the ptracer detaches.
*/
if (likely(!ptrace) && unlikely(task_ptrace(p))) {
/* it will become visible, clear notask_error */
wo->notask_error = 0;
return 0;
}
/* we don't reap group leaders with subthreads */
if (!delay_group_leader(p))
return wait_task_zombie(wo, p);
/*
* Allow access to stopped/continued state via zombie by
* falling through. Clearing of notask_error is complex.
*
* When !@ptrace:
*
* If WEXITED is set, notask_error should naturally be
* cleared. If not, subset of WSTOPPED|WCONTINUED is set,
* so, if there are live subthreads, there are events to
* wait for. If all subthreads are dead, it's still safe
* to clear - this function will be called again in finite
* amount time once all the subthreads are released and
* will then return without clearing.
*
* When @ptrace:
*
* Stopped state is per-task and thus can't change once the
* target task dies. Only continued and exited can happen.
* Clear notask_error if WCONTINUED | WEXITED.
*/
if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
wo->notask_error = 0;
} else {
/*
* If @p is ptraced by a task in its real parent's group,
* hide group stop/continued state when looking at @p as
* the real parent; otherwise, a single stop can be
* reported twice as group and ptrace stops.
*
* If a ptracer wants to distinguish the two events for its
* own children, it should create a separate process which
* takes the role of real parent.
*/
if (likely(!ptrace) && task_ptrace(p) &&
same_thread_group(p->parent, p->real_parent))
return 0;
/*
* @p is alive and it's gonna stop, continue or exit, so
* there always is something to wait for.
*/
wo->notask_error = 0;
}
/*
* It's stopped or running now, so it might
* later continue, exit, or stop again.
* Wait for stopped. Depending on @ptrace, different stopped state
* is used and the two don't interact with each other.
*/
wo->notask_error = 0;
if (task_stopped_code(p, ptrace))
return wait_task_stopped(wo, ptrace, p);
/*
* Wait for continued. There's only one continued state and the
* ptracer can consume it which can confuse the real parent. Don't
* use WCONTINUED from ptracer. You don't need or want it.
*/
return wait_task_continued(wo, p);
}