linux-kernel - Re: [PATCH] kprobes: fix trace_probe flags in enable_trace

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Message-Id: <20180726003524.e5ad32fc6b30476ccb0ebdc5@kernel.org>
Date:   Thu, 26 Jul 2018 00:35:24 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Artem Savkov <asavkov@...hat.com>, Ingo Molnar <mingo@...hat.com>,
        linux-kernel@...r.kernel.org, Josh Poimboeuf <jpoimboe@...hat.com>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [PATCH] kprobes: fix trace_probe flags in enable_trace_kprobe

On Wed, 25 Jul 2018 09:21:51 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> 
> [ Adding Masami to Cc ]
> 
> On Wed, 25 Jul 2018 12:28:26 +0200
> Artem Savkov <asavkov@...hat.com> wrote:
> 
> > If enable_trace_kprobe fails to enable the probe in enable_k(ret)probe
> > it returns an error, but does not unset the tp flags it set previosly.
> > This results in a probe being considered enabled and failures like being
> > unable to remove the probe through kprobe_events file since probes_open()
> > expects every probe to be disabled.
> > 
> 
> Looks good to me. Masami, want to ack it?

Yes, looks good to me too.

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

Thanks Artem!

> 
> -- Steve
> 
> > Signed-off-by: Artem Savkov <asavkov@...hat.com>
> > ---
> >  kernel/trace/trace_kprobe.c | 13 +++++++++++--
> >  1 file changed, 11 insertions(+), 2 deletions(-)
> > 
> > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> > index 21f718472942..fb887ced5056 100644
> > --- a/kernel/trace/trace_kprobe.c
> > +++ b/kernel/trace/trace_kprobe.c
> > @@ -400,11 +400,10 @@ static struct trace_kprobe *find_trace_kprobe(const char *event,
> >  static int
> >  enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
> >  {
> > +	struct event_file_link *link;
> >  	int ret = 0;
> >  
> >  	if (file) {
> > -		struct event_file_link *link;
> > -
> >  		link = kmalloc(sizeof(*link), GFP_KERNEL);
> >  		if (!link) {
> >  			ret = -ENOMEM;
> > @@ -424,6 +423,16 @@ enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
> >  		else
> >  			ret = enable_kprobe(&tk->rp.kp);
> >  	}
> > +
> > +	if (ret) {
> > +		if (file) {
> > +			list_del(&link->list);
> > +			kfree(link);
> > +			tk->tp.flags &= ~TP_FLAG_TRACE;
> > +		} else {
> > +			tk->tp.flags &= ~TP_FLAG_PROFILE;
> > +		}
> > +	}
> >   out:
> >  	return ret;
> >  }
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>