From: Steven Rostedt <rostedt@goodmis.org>
To: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>,
jikos@kernel.org, joe.lawrence@redhat.com, jpoimboe@redhat.com,
mingo@redhat.com, linux-kernel@vger.kernel.org,
live-patching@vger.kernel.org
Subject: Re: [PATCH v2] ftrace: Introduce PERMANENT ftrace_ops flag
Date: Tue, 15 Oct 2019 09:36:42 -0400 [thread overview]
Message-ID: <20191015093642.72e872d0@gandalf.local.home> (raw)
In-Reply-To: <alpine.LSU.2.21.1910151244550.30206@pobox.suse.cz>
On Tue, 15 Oct 2019 12:50:59 +0200 (CEST)
Miroslav Benes <mbenes@suse.cz> wrote:
> > > > @@ -6752,12 +6764,19 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
> > > > ftrace_startup_sysctl();
> > > >
> > > > } else {
> > > > + if (is_permanent_ops_registered()) {
> > > > + ftrace_enabled = last_ftrace_enabled;
> > >
> > > Although this is not incorrect, but may be somewhat confusing.
> > >
> > > At this location, last_ftrace_enabled is always true.
> > >
> > > I'm thinking this would be better to simply set it to false here.
> >
> > IMHO, we want to set ftrace_enabled = true here.
Yes, I meant true (don't know why I said false :-/ )
> >
> > It was set to "false" by writing to the sysfs file. But the change
> > gets rejected. ftrace will stay enabled. So, we should set
> > the value back to "true".
>
> That's correct.
>
> I can make it explicit as proposed. I just thought that 'ftrace_enabled =
> last_ftrace_enabled' was clear enough given Petr's explanation.
>
> > > > + ret = -EBUSY;
> > > > + goto out;
> > > > + }
> > > > +
> > > > /* stopping ftrace calls (just send to ftrace_stub) */
> > > > ftrace_trace_function = ftrace_stub;
> > > >
> > > > ftrace_shutdown_sysctl();
> > > > }
> > > >
> > > > + last_ftrace_enabled = !!ftrace_enabled;
> > > > out:
> > >
> > > And move the assignment of last_ftrace_enabled to after the "out:"
> > > label.
> >
> > This change might make sense anyway. But it is not strictly necessary
> > from my POV.
>
> If it stays before "out:" label, last_ftrace_enabled is set if and only if
> it has to be set. I think it is better, but I can, of course, move it in
> v3 if Steven prefers it.
I don't have any strong feelings here. If you want to keep it like
this, I wont argue.
-- Steve
next prev parent reply other threads:[~2019-10-15 13:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-14 10:59 [PATCH v2] ftrace: Introduce PERMANENT ftrace_ops flag Miroslav Benes
2019-10-14 14:26 ` Petr Mladek
2019-10-14 15:17 ` Steven Rostedt
2019-10-15 7:45 ` Petr Mladek
2019-10-15 10:50 ` Miroslav Benes
2019-10-15 13:36 ` Steven Rostedt [this message]
2019-10-14 22:31 ` Joe Lawrence
2019-10-15 11:23 ` Miroslav Benes
2019-10-15 13:25 ` Joe Lawrence
2019-10-15 14:02 ` Miroslav Benes
2019-10-15 14:58 ` Joe Lawrence
2019-10-16 5:02 ` Kamalesh Babulal
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