linux-kernel - Re: [PATCH v3 31/51] x86/dumpstack: allow preemption in show_stack_log_lvl() and dump

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Message-ID: <20160815153238.prejjyfqsn65xcq2@treble>
Date:	Mon, 15 Aug 2016 10:32:38 -0500
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	"H . Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Brian Gerst <brgerst@...il.com>,
	Kees Cook <keescook@...omium.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Byungchul Park <byungchul.park@....com>,
	Nilay Vaish <nilayvaish@...il.com>
Subject: Re: [PATCH v3 31/51] x86/dumpstack: allow preemption in
 show_stack_log_lvl() and dump_trace()

On Sun, Aug 14, 2016 at 12:45:35AM -0700, Andy Lutomirski wrote:
> On Fri, Aug 12, 2016 at 7:28 AM, Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> > show_stack_log_lvl() and dump_trace() are already preemption safe:
> >
> > - If they're running in interrupt context, preemption is already
> >   disabled and the percpu irq stack pointers can be trusted.
> 
> I agree with the patch, but I have a minor nitpick about the
> description.  The "irq stack" is an actual thing, but the relevant
> stacks here aren't just the irq stack: they're the irq stack, the IST
> stacks (on 64-bit), and the NMI stack (on 32-bit).  The same logic
> applies, though.

Yeah.  Maybe I'll just remove the "irq" qualifier and instead call them
"percpu stack pointers".

-- 
Josh