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From: Rusty Russell <rusty@rustcorp.com.au>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v2][GIT PULL] tracing: Prevent unloadable modules from using trace_bprintk()
Date: Fri, 22 Oct 2010 14:13:28 +1030	[thread overview]
Message-ID: <201010221413.28588.rusty@rustcorp.com.au> (raw)
In-Reply-To: <1287700463.16971.603.camel@gandalf.stny.rr.com>

On Fri, 22 Oct 2010 09:04:23 am Steven Rostedt wrote:
> On Fri, 2010-10-22 at 08:05 +1030, Rusty Russell wrote:
> > On Fri, 22 Oct 2010 12:15:42 am Steven Rostedt wrote:
> > > 
> > > Ingo,
> > > 
> > > This is based off of my core-2 branch. I'm moved this patch after that
> > > so if anyone has any objections, I can change this patch without holding
> > > off the previous one.
> > 
> > I think disabling use in modules is lazy,
> 
> and safer.

Well then just delete trace_bprintk altogether.  Even safer!

> > Can't you detect this on module unload and fix it up?  Or delay freeing the
> > module until the trace ring is emptied?
> 
> One possibility is to magically make all string formats used in
> trace_printk into its own section, and keep it allocated until the ring
> buffer is empty. Or, we can just do that with the module's entire string
> section, since we know whether or not that module has a trace_printk in
> it or not.

Exactly.  Set a flag in the module if it resolves trace_printk, and defer freeing
the module in that case.  This shouldn't be that hard...

Rusty.

  reply	other threads:[~2010-10-22  3:43 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-21 13:45 [PATCH v2][GIT PULL] tracing: Prevent unloadable modules from using trace_bprintk() Steven Rostedt
2010-10-21 21:35 ` Rusty Russell
2010-10-21 22:34   ` Steven Rostedt
2010-10-22  3:43     ` Rusty Russell [this message]
2010-10-22  3:58       ` Steven Rostedt
2010-10-22  4:34         ` Rusty Russell
2010-10-22  5:30           ` Li Zefan
2010-10-22 13:49             ` Steven Rostedt
2010-10-25  1:32               ` Li Zefan
2010-10-22  8:05 ` Ingo Molnar
2010-10-22 13:50   ` Steven Rostedt

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