From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933353Ab2FEK2V (ORCPT ); Tue, 5 Jun 2012 06:28:21 -0400 Received: from mail7.hitachi.co.jp ([133.145.228.42]:50135 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933155Ab2FEK2P (ORCPT ); Tue, 5 Jun 2012 06:28:15 -0400 X-AuditID: b753bd60-92fc6ba000002ea5-77-4fcddf3d9381 X-AuditID: b753bd60-92fc6ba000002ea5-77-4fcddf3d9381 From: Masami Hiramatsu Subject: [PATCH -tip v2 5/9] kprobes: Inverse taking of module_mutex with kprobe_mutex To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Ananth N Mavinakayanahalli , "Frank Ch. Eigler" , Andrew Morton , Frederic Weisbecker , yrl.pp-manager.tt@hitachi.com, Masami Hiramatsu , Steven Rostedt Date: Tue, 05 Jun 2012 19:28:14 +0900 Message-ID: <20120605102814.27845.21047.stgit@localhost.localdomain> In-Reply-To: <20120605102734.27845.43401.stgit@localhost.localdomain> References: <20120605102734.27845.43401.stgit@localhost.localdomain> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt Currently module_mutex is taken before kprobe_mutex, but this can cause issues when we have kprobes register ftrace, as the ftrace mutex is taken before enabling a tracepoint, which currently takes the module mutex. If module_mutex is taken before kprobe_mutex, then we can not have kprobes use the ftrace infrastructure. There seems to be no reason that the kprobe_mutex can't be taken before the module_mutex. Running lockdep shows that it is safe among the kernels I've run. Cc: Masami Hiramatsu Signed-off-by: Steven Rostedt --- kernel/kprobes.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index c62b854..7a8a122 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -561,9 +561,9 @@ static __kprobes void kprobe_optimizer(struct work_struct *work) { LIST_HEAD(free_list); + mutex_lock(&kprobe_mutex); /* Lock modules while optimizing kprobes */ mutex_lock(&module_mutex); - mutex_lock(&kprobe_mutex); /* * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) @@ -586,8 +586,8 @@ static __kprobes void kprobe_optimizer(struct work_struct *work) /* Step 4: Free cleaned kprobes after quiesence period */ do_free_cleaned_kprobes(&free_list); - mutex_unlock(&kprobe_mutex); mutex_unlock(&module_mutex); + mutex_unlock(&kprobe_mutex); /* Step 5: Kick optimizer again if needed */ if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))