From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753170Ab3EPLve (ORCPT ); Thu, 16 May 2013 07:51:34 -0400 Received: from mail7.hitachi.co.jp ([133.145.228.42]:50683 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752843Ab3EPLv2 (ORCPT ); Thu, 16 May 2013 07:51:28 -0400 X-AuditID: 85900ec0-d60ccb900000151e-03-5194c83eed8c Subject: [PATCH 1/5] [BUGFIX] tracing: Returns -EBUSY when event_enable_func fails to get module To: linux-kernel@vger.kernel.org, Steven Rostedt From: Masami Hiramatsu Cc: Srikar Dronamraju , Frederic Weisbecker , yrl.pp-manager.tt@hitachi.com, Oleg Nesterov , Ingo Molnar , Tom Zanussi Date: Thu, 16 May 2013 20:48:49 +0900 Message-ID: <20130516114848.13508.97899.stgit@mhiramat-M0-7522> In-Reply-To: <20130516114839.13508.92844.stgit@mhiramat-M0-7522> References: <20130516114839.13508.92844.stgit@mhiramat-M0-7522> User-Agent: StGit/0.15 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 Since try_module_get returns false( = 0) when it fails to pindown a module, event_enable_func() returns 0 which means "succeed". This can cause a kernel panic when the entry is removed, because the event is already released. This fixes the bug by returning -EBUSY, because the reason why it fails is under removing module at that time. Signed-off-by: Masami Hiramatsu Cc: Steven Rostedt Cc: Frederic Weisbecker Cc: Ingo Molnar --- kernel/trace/trace_events.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 7a0cf68..27963e2 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -2072,8 +2072,10 @@ event_enable_func(struct ftrace_hash *hash, out_reg: /* Don't let event modules unload while probe registered */ ret = try_module_get(file->event_call->mod); - if (!ret) + if (!ret) { + ret = -EBUSY; goto out_free; + } ret = __ftrace_event_enable_disable(file, 1, 1); if (ret < 0)