Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752631AbbKQLHx (ORCPT ); Tue, 17 Nov 2015 06:07:53 -0500 Received: from casper.infradead.org ([85.118.1.10]:58422 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750913AbbKQLHw (ORCPT ); Tue, 17 Nov 2015 06:07:52 -0500 Date: Tue, 17 Nov 2015 12:07:49 +0100 From: Peter Zijlstra To: Vineet Gupta Cc: Alexey Brodkin , arcml , lkml Subject: Re: local64_cmpxchg() in arc_perf_event_update() Message-ID: <20151117110749.GT3816@twins.programming.kicks-ass.net> References: <1445286926.3913.13.camel@synopsys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 530 Lines: 13 On Tue, Nov 17, 2015 at 09:14:59AM +0000, Vineet Gupta wrote: > Let's check with Peter as I'm not sure how exactly the read call will > nest for same counter on same core ? Various possible ways, but the easiest is userspace doing a sys_read() on the counter while the NMI happens. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/