linux-kernel - Re: [RFC] x86_64: A real proposal for iret-less return to kernel

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Message-ID: <alpine.LNX.2.00.1405212348140.12047@pobox.suse.cz>
Date:	Wed, 21 May 2014 23:50:49 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	"H. Peter Anvin" <hpa@...or.com>
cc:	Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Lutomirski <luto@...capital.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Steven Rostedt <rostedt@...dmis.org>,
	Andi Kleen <andi@...stfloor.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	"Luck, Tony" <tony.luck@...el.com>
Subject: Re: [RFC] x86_64: A real proposal for iret-less return to kernel

On Wed, 21 May 2014, H. Peter Anvin wrote:

> > I certainly like this way of handling it. We can even issue a nice
> > banner saying something like "You're f*cked - go change hw."
> 
> Actually, it would be a lot better to panic than deadlock (HA systems
> tend to have something in place to catch the panic and/or reboot).  Any
> way we can see if the CPU is already holding that lock and panic in that
> case?

Well, spin_trylock() and then either spin_unlock() and proceed sending 
the signal, otherwise panic().

-- 
Jiri Kosina
SUSE Labs
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