linux-kernel - Re: [PATCH v2 35/40] tracing: Reverse the order event_mutex/trace_types

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: <20170908160039.24ab418c@gandalf.local.home>
Date:   Fri, 8 Sep 2017 16:00:39 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Tom Zanussi <tom.zanussi@...ux.intel.com>
Cc:     tglx@...utronix.de, mhiramat@...nel.org, namhyung@...nel.org,
        vedang.patel@...el.com, bigeasy@...utronix.de,
        joel.opensrc@...il.com, joelaf@...gle.com,
        mathieu.desnoyers@...icios.com, baohong.liu@...el.com,
        linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org
Subject: Re: [PATCH v2 35/40] tracing: Reverse the order
 event_mutex/trace_types_lock are taken

On Fri, 8 Sep 2017 15:41:36 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> On Fri, 8 Sep 2017 15:31:35 -0400
> Steven Rostedt <rostedt@...dmis.org> wrote:
> 
> > On Tue,  5 Sep 2017 16:57:47 -0500
> > Tom Zanussi <tom.zanussi@...ux.intel.com> wrote:
> >   
> > > Change the order event_mutex and trace_types_lock are taken, to avoid
> > > circular dependencies and lockdep spew.
> > > 
> > > Changing the order shouldn't matter to any current code, but does to
> > > anything that takes the event_mutex first and then trace_types_lock.
> > > This is the case when calling tracing_set_clock from inside an event
> > > command, which already holds the event_mutex.    
> > 
> > This is a very scary patch. I'll apply it and run a bunch of tests with
> > lockdep enabled. Let's see what blows up (or not).  
> 
> Boom!
>


> It appears to be caused by instance creation. I'll look at that.

OK, this may be a simple fix. I'll send you a patch to fold in after I
finish testing it.

-- Steve