From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752607Ab0JPCZw (ORCPT ); Fri, 15 Oct 2010 22:25:52 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:36790 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752438Ab0JPCZv (ORCPT ); Fri, 15 Oct 2010 22:25:51 -0400 X-Authority-Analysis: v=1.1 cv=iGF3DqghDyT/uy4mV2LvOKNXCATMSjL+tOl9cucoGVk= c=1 sm=0 a=gJRBYOTBAWgA:10 a=Q9fys5e9bTEA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=er-gvXSu9-3I63Nr6b8A:9 a=9Z_JELsnB_QAdRZUUSkA:7 a=B8HRAP43mzGLHAOxeJ2Fbh2lrukA:4 a=PUjeQqilurYA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Subject: Re: [PATCH 4/9] jump label: Fix deadlock b/w jump_label_mutex vs. text_mutex From: Steven Rostedt To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Frederic Weisbecker , Masami Hiramatsu , Jason Baron In-Reply-To: <1287176134.1998.113.camel@laptop> References: <20101015200949.134732894@goodmis.org> <20101015201036.691801067@goodmis.org> <1287176134.1998.113.camel@laptop> Content-Type: text/plain; charset="ISO-8859-15" Date: Fri, 15 Oct 2010 22:25:49 -0400 Message-ID: <1287195949.16971.45.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2010-10-15 at 22:55 +0200, Peter Zijlstra wrote: > On Fri, 2010-10-15 at 16:09 -0400, Steven Rostedt wrote: > > +void jump_label_lock(void) > > +{ > > + mutex_lock(&jump_label_mutex); > > +} > > + > > > +++ b/kernel/kprobes.c > > @@ -1145,13 +1145,16 @@ int __kprobes register_kprobe(struct kprobe *p) > > return ret; > > > > preempt_disable(); > > + jump_label_lock(); > > How exactly does that work? > This patch should fix it (compiled tested only). If all agree, I'll add it to the series. -- Steve diff --git a/kernel/kprobes.c b/kernel/kprobes.c index d45d72e..0dbd328 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1144,17 +1144,13 @@ int __kprobes register_kprobe(struct kprobe *p) if (ret) return ret; - preempt_disable(); jump_label_lock(); + preempt_disable(); if (!kernel_text_address((unsigned long) p->addr) || in_kprobes_functions((unsigned long) p->addr) || ftrace_text_reserved(p->addr, p->addr) || - jump_label_text_reserved(p->addr, p->addr)) { - preempt_enable(); - jump_label_unlock(); - return -EINVAL; - } - jump_label_unlock(); + jump_label_text_reserved(p->addr, p->addr)) + goto fail_with_jump_label; /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */ p->flags &= KPROBE_FLAG_DISABLED; @@ -1168,10 +1164,9 @@ int __kprobes register_kprobe(struct kprobe *p) * We must hold a refcount of the probed module while updating * its code to prohibit unexpected unloading. */ - if (unlikely(!try_module_get(probed_mod))) { - preempt_enable(); - return -EINVAL; - } + if (unlikely(!try_module_get(probed_mod))) + goto fail_with_jump_label; + /* * If the module freed .init.text, we couldn't insert * kprobes in there. @@ -1179,11 +1174,11 @@ int __kprobes register_kprobe(struct kprobe *p) if (within_module_init((unsigned long)p->addr, probed_mod) && probed_mod->state != MODULE_STATE_COMING) { module_put(probed_mod); - preempt_enable(); - return -EINVAL; + goto fail_with_jump_label; } } preempt_enable(); + jump_label_unlock(); p->nmissed = 0; INIT_LIST_HEAD(&p->list); @@ -1225,6 +1220,11 @@ out: module_put(probed_mod); return ret; + +fail_with_jump_label: + preempt_enable(); + jump_label_unlock(); + return -EINVAL; } EXPORT_SYMBOL_GPL(register_kprobe);