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Message-ID: <20090129164305.GB21030@redhat.com>
Date: Thu, 29 Jan 2009 17:43:05 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, dvlasenk@...hat.com,
jmarchan@...hat.com, roland@...hat.com
Subject: Re: +
ptrace-reintroduce-__ptrace_detach-as-a-callee-of-ptrace_exit.patch
added to -mm tree
> The patch titled
> ptrace: reintroduce __ptrace_detach() as a callee of ptrace_exit()
> has been added to the -mm tree. Its filename is
> ptrace-reintroduce-__ptrace_detach-as-a-callee-of-ptrace_exit.patch
Please find the new version below. Re-diff + update the comments.
----------
[PATCH 3/4] ptrace: reintroduce __ptrace_detach() as a callee of ptrace_exit()
No functional changes, preparation for the next patch.
Move the "should we release this child" logic into the separate handler,
__ptrace_detach().
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
--- 6.29-rc3/kernel/exit.c~3_REINTRODUCE_DETACH 2009-01-29 16:40:38.000000000 +0100
+++ 6.29-rc3/kernel/exit.c 2009-01-29 17:08:27.000000000 +0100
@@ -741,6 +741,38 @@ static int ignoring_children(struct sigh
return ret;
}
+/* Returns nonzero if the tracee should be released. */
+int __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
+{
+ __ptrace_unlink(p);
+
+ if (p->exit_state != EXIT_ZOMBIE)
+ return 0;
+ /*
+ * If it's a zombie, our attachedness prevented normal
+ * parent notification or self-reaping. Do notification
+ * now if it would have happened earlier. If it should
+ * reap itself we return true.
+ *
+ * If it's our own child, there is no notification to do.
+ * But if our normal children self-reap, then this child
+ * was prevented by ptrace and we must reap it now.
+ */
+ if (!task_detached(p) && thread_group_empty(p)) {
+ if (!same_thread_group(p->real_parent, tracer))
+ do_notify_parent(p, p->exit_signal);
+ else if (ignoring_children(tracer->sighand))
+ p->exit_signal = -1;
+ }
+
+ if (!task_detached(p))
+ return 0;
+
+ /* Mark it as in the process of being reaped. */
+ p->exit_state = EXIT_DEAD;
+ return 1;
+}
+
/*
* Detach all tasks we were using ptrace on.
* Any that need to be release_task'd are put on the @dead list.
@@ -752,36 +784,8 @@ static void ptrace_exit(struct task_stru
struct task_struct *p, *n;
list_for_each_entry_safe(p, n, &parent->ptraced, ptrace_entry) {
- __ptrace_unlink(p);
-
- if (p->exit_state != EXIT_ZOMBIE)
- continue;
-
- /*
- * If it's a zombie, our attachedness prevented normal
- * parent notification or self-reaping. Do notification
- * now if it would have happened earlier. If it should
- * reap itself, add it to the @dead list. We can't call
- * release_task() here because we already hold tasklist_lock.
- *
- * If it's our own child, there is no notification to do.
- * But if our normal children self-reap, then this child
- * was prevented by ptrace and we must reap it now.
- */
- if (!task_detached(p) && thread_group_empty(p)) {
- if (!same_thread_group(p->real_parent, parent))
- do_notify_parent(p, p->exit_signal);
- else if (ignoring_children(parent->sighand))
- p->exit_signal = -1;
- }
-
- if (task_detached(p)) {
- /*
- * Mark it as in the process of being reaped.
- */
- p->exit_state = EXIT_DEAD;
+ if (__ptrace_detach(parent, p))
list_add(&p->ptrace_entry, dead);
- }
}
}
--
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