From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752841AbbGYERE (ORCPT ); Sat, 25 Jul 2015 00:17:04 -0400 Received: from mail.skyhub.de ([78.46.96.112]:60563 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751369AbbGYERC (ORCPT ); Sat, 25 Jul 2015 00:17:02 -0400 Date: Sat, 25 Jul 2015 06:16:56 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: Andy Lutomirski , X86 ML , "linux-kernel@vger.kernel.org" , Brian Gerst , Steven Rostedt , Willy Tarreau , Thomas Gleixner , Peter Zijlstra , Linus Torvalds Subject: Re: [PATCH 1/3] x86/entry/64: Refactor IRQ stacks and make then NMI-safe Message-ID: <20150725041656.GB32606@nazgul.tnic> References: <040374ca9800988a0ed35ea9ddeb4a762c1371fa.1437690860.git.luto@kernel.org> <20150724102503.GA19090@nazgul.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 24, 2015 at 11:02:51AM -0700, Andy Lutomirski wrote: > So really the only difference between this simple approach (which is > more or less what we do now) and my fancy approach is that a kernel > instruction breakpoint will cause do_debug to run on the initial stack > instead of the IRQ stack. Sounds ok to me. What would be the worst thing if we limited the #DB stack? Some breakpoints will get ignored? In an endless stream of breakpoints hammering? Doesn't sound like a valid use case to me, does it? > I'm still tempted to say we should use my overly paranoid atomic > approach for now and optimize later,... But why change it if the simple approach of incrementing irq_count first is still fine? I think we want to KISS here exactly because apparently complexity in that area is a serious PITA... -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. --