linux-kernel - Re: [PATCH] ftrace: Remove possible deadlock between register_kprobe() and ftrace_run_update

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Date:   Fri, 28 Jun 2019 09:54:24 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Miroslav Benes <mbenes@...e.cz>,
        Johannes Erdfelt <johannes@...felt.com>,
        Jessica Yu <jeyu@...nel.org>, Jiri Kosina <jikos@...nel.org>,
        mhiramat@...nel.org, Ingo Molnar <mingo@...nel.org>,
        tglx@...utronix.de, torvalds@...ux-foundation.org,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        linux-kernel@...r.kernel.org, live-patching@...r.kernel.org
Subject: Re: [PATCH] ftrace: Remove possible deadlock between
 register_kprobe() and ftrace_run_update_code()

On Fri, 28 Jun 2019 12:52:32 +0200
Petr Mladek <pmladek@...e.com> wrote:

> On Fri 2019-06-28 09:32:03, Miroslav Benes wrote:
> > On Thu, 27 Jun 2019, Petr Mladek wrote:  
> > > @@ -2611,12 +2610,10 @@ static void ftrace_run_update_code(int command)
> > >  {
> > >  	int ret;
> > >  
> > > -	mutex_lock(&text_mutex);
> > > -
> > >  	ret = ftrace_arch_code_modify_prepare();
> > >  	FTRACE_WARN_ON(ret);
> > >  	if (ret)
> > > -		goto out_unlock;
> > > +		return ret;  
> > 
> > Should be just "return;", because the function is "static void".  
> 
> Grr, I usually check compiler warnings but I evidently skipped it
> in this case :-(
> 
> Steven, should I send a fixed/folloup patch or will you just
> fix it when pushing?
> 

I'll fix it up.

-- Steve