From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 670E9C432C3 for ; Fri, 29 Nov 2019 05:59:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 41C18215F1 for ; Fri, 29 Nov 2019 05:59:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726829AbfK2F7Q (ORCPT ); Fri, 29 Nov 2019 00:59:16 -0500 Received: from mx2.suse.de ([195.135.220.15]:40140 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725860AbfK2F7P (ORCPT ); Fri, 29 Nov 2019 00:59:15 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 29988ACE0; Fri, 29 Nov 2019 05:59:14 +0000 (UTC) Subject: Re: [PATCH v2] xen/events: remove event handling recursion detection To: Boris Ostrovsky , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: Stefano Stabellini References: <20191128084545.13831-1-jgross@suse.com> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <6483de2d-963c-3b5e-150a-641e070e3d0e@suse.com> Date: Fri, 29 Nov 2019 06:59:12 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28.11.19 22:37, Boris Ostrovsky wrote: > On 11/28/19 3:45 AM, Juergen Gross wrote: >> - >> static void __xen_evtchn_do_upcall(void) >> { >> struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu); >> - int cpu = get_cpu(); >> - unsigned count; >> + int cpu = smp_processor_id(); >> >> do { >> vcpu_info->evtchn_upcall_pending = 0; >> >> - if (__this_cpu_inc_return(xed_nesting_count) - 1) >> - goto out; >> - >> xen_evtchn_handle_events(cpu); >> >> BUG_ON(!irqs_disabled()); >> >> - count = __this_cpu_read(xed_nesting_count); >> - __this_cpu_write(xed_nesting_count, 0); >> - } while (count != 1 || vcpu_info->evtchn_upcall_pending); >> - >> -out: >> + rmb(); /* Hypervisor can set upcall pending. */ > > virt_rmb() perhaps then? Yes, that's better. Juergen