linux-kernel - [PATCH 13/16] ptrace: reorganize __ptrace_unlink() and ptrace

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1291654624-6230-14-git-send-email-tj@kernel.org>
Date:	Mon,  6 Dec 2010 17:57:01 +0100
From:	Tejun Heo <tj@...nel.org>
To:	oleg@...hat.com, roland@...hat.com, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	rjw@...k.pl, jan.kratochvil@...hat.com
Cc:	Tejun Heo <tj@...nel.org>
Subject: [PATCH 13/16] ptrace: reorganize __ptrace_unlink() and ptrace_untrace()

* Collapse ptrace_untrace() into __ptrace_unlink().

* Always do the whole unlinking inside siglock.

* Untracing is done before unlinking.

This is to prepare for further changes.  As the whole
unlinking/tracing is done inside both tasklist lock and siglock, the
reordering doesn't cause any visible behavior difference.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Roland McGrath <roland@...hat.com>
---
 kernel/ptrace.c |   40 ++++++++++++++++++----------------------
 1 files changed, 18 insertions(+), 22 deletions(-)

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 5191301..6ac12f4 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -38,45 +38,41 @@ void __ptrace_link(struct task_struct *child, struct task_struct *new_parent)
 }
 
 /*
- * Turn a tracing stop into a normal stop now, since with no tracer there
- * would be no way to wake it up with SIGCONT or SIGKILL.  If there was a
- * signal sent that would resume the child, but didn't because it was in
- * TASK_TRACED, resume it now.
- * Requires that irqs be disabled.
+ * unptrace a task: move it back to its original parent and remove it
+ * from the ptrace list.
+ *
+ * Turn a tracing stop into a normal stop now, since with no tracer
+ * there would be no way to wake it up with SIGCONT or SIGKILL.  If
+ * there was a signal sent that would resume the child, but didn't
+ * because it was in TASK_TRACED, resume it now.  Requires that irqs
+ * be disabled.
+ *
+ * Must be called with the tasklist lock write-held.
  */
-static void ptrace_untrace(struct task_struct *child)
+void __ptrace_unlink(struct task_struct *child)
 {
+	struct signal_struct *sig = child->signal;
+
+	BUG_ON(!child->ptrace);
+
 	spin_lock(&child->sighand->siglock);
+
 	if (task_is_traced(child)) {
 		/*
 		 * If group stop is completed or in progress, it should
 		 * participate in the group stop.  Set GROUP_STOP_PENDING
 		 * before kicking it.
 		 */
-		if (child->signal->flags & SIGNAL_STOP_STOPPED ||
-		    child->signal->group_stop_count)
+		if (sig->flags & SIGNAL_STOP_STOPPED || sig->group_stop_count)
 			child->group_stop |= GROUP_STOP_PENDING;
 		signal_wake_up(child, 1);
 	}
-	spin_unlock(&child->sighand->siglock);
-}
-
-/*
- * unptrace a task: move it back to its original parent and
- * remove it from the ptrace list.
- *
- * Must be called with the tasklist lock write-held.
- */
-void __ptrace_unlink(struct task_struct *child)
-{
-	BUG_ON(!child->ptrace);
 
 	child->ptrace = 0;
 	child->parent = child->real_parent;
 	list_del_init(&child->ptrace_entry);
 
-	if (task_is_traced(child))
-		ptrace_untrace(child);
+	spin_unlock(&child->sighand->siglock);
 }
 
 static int ptrace_wait_trap(void *flags)
-- 
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/