Re: [PATCH 1/3] x86/entry/64: Refactor IRQ stacks and make then NMI-safe

From: Steven Rostedt <rostedt@goodmis.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@kernel.org>, Andy Lutomirski <luto@kernel.org>,
	X86 ML <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Brian Gerst <brgerst@gmail.com>, Willy Tarreau <w@1wt.eu>,
	Borislav Petkov <bp@alien8.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 1/3] x86/entry/64: Refactor IRQ stacks and make then NMI-safe
Date: Wed, 5 Aug 2015 14:27:36 -0400	[thread overview]
Message-ID: <20150805142736.7dba3c8f@gandalf.local.home> (raw)
In-Reply-To: <CALCETrV_ei6jJyzf8HFEZqUwk4k+SR+Ze=iwuXDmMYDynWDrjg@mail.gmail.com>

On Wed, 5 Aug 2015 11:24:54 -0700
Andy Lutomirski <luto@amacapital.net> wrote:

> On Wed, Aug 5, 2015 at 1:59 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > * Andy Lutomirski <luto@kernel.org> wrote:
> >
> >> --- a/arch/x86/kernel/process_64.c
> >> +++ b/arch/x86/kernel/process_64.c
> >> @@ -280,6 +280,10 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
> >>       unsigned fsindex, gsindex;
> >>       fpu_switch_t fpu_switch;
> >>
> >> +#ifdef CONFIG_DEBUG_ENTRY
> >> +     WARN_ON(this_cpu_read(irq_count));
> >> +#endif
> >
> > Please introduce a less noisy (to the eyes) version of this, something like:
> >
> >         WARN_ON_DEBUG_ENTRY(this_cpu_read(irq_count));
> >
> > or so, similar to WARN_ON_FPU().
> 
> I can do that (or "DEBUG_ENTRY_WARN_ON"?  we seem to be inconsistent
> about ordering).
> 
> Or would if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) WARN_ON(...) be better?
> 

Does WARN_ON(IS_ENABLED(CONFIG_DEBUG_ENTRY) && this_cpu_read(irq_count))
work?

-- Steve