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Message-ID: <1287195370.16971.41.camel@gandalf.stny.rr.com>
Date: Fri, 15 Oct 2010 22:16:10 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
Andrew Morton <akpm@...ux-foundation.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
Jason Baron <jbaron@...hat.com>
Subject: Re: [PATCH 4/9] jump label: Fix deadlock b/w jump_label_mutex vs.
text_mutex
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?
Ouch! Good catch!
I'll do the James Bottomley and blame jet lag ;-)
-- Steve
>
> > 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();
--
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