linux-kernel - Re: [PATCH v2] tracing: Make sure RCU is watching before calling a stack trace

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: <alpine.LSU.2.20.1705181547170.31625@pobox.suse.cz>
Date:   Thu, 18 May 2017 15:48:55 +0200 (CEST)
From:   Miroslav Benes <mbenes@...e.cz>
To:     Steven Rostedt <rostedt@...dmis.org>
cc:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v2] tracing: Make sure RCU is watching before calling a
 stack trace

On Thu, 18 May 2017, Steven Rostedt wrote:

> 
> From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
> 
> As stack tracing now requires "rcu watching", force RCU to be watching when
> recording a stack trace.
> 
> Link: http://lkml.kernel.org/r/20170512172449.879684501@goodmis.org
> 
> Cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> ---
> 
> Changes since v1:
> 
>    My testing discovered that the stack trace can be called with
>    interrupts enabled, which is a no no to have when calling
>    rcu_irq_enter(). When interrupts are enabled, as with being in an
>    NMI, RCU will also be watching.

Would rcu_irq_enter_irqson() help then? This is what Petr used in a live 
patching handler.

Your solution works too, of course. Just asking if I am not missing 
something.

Thanks,
Miroslav