From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1754091AbdARO0T (ORCPT <rfc822;w@1wt.eu>);
        Wed, 18 Jan 2017 09:26:19 -0500
Received: from aer-iport-3.cisco.com ([173.38.203.53]:1575 "EHLO
        aer-iport-3.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1753211AbdARO0S (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Wed, 18 Jan 2017 09:26:18 -0500
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: =?us-ascii?q?A0CaAwBYen9Y/xbLJq1dGQEBAQEBAQEBA?=
 =?us-ascii?q?QEBBwEBAQEBgzkBAQEBAYEBj1GQcR+THYIPgguCbIM2AoI3FwECAQEBAQEBAWM?=
 =?us-ascii?q?ohGoBBThBEAsOCi4fOAYNCAEBiH+yBoomAQEBAQEBAQEBAQEBAQEBAQEBAQEBH?=
 =?us-ascii?q?ROIPQiCYYotAQSbQQEakUeKL4Y+SJInIQI0gUQVhm88iTYBAQE?=
X-IronPort-AV: E=Sophos;i="5.33,249,1477958400"; 
   d="scan'208";a="649928257"
Subject: Re: [PATCH] x86/ioapic: add IO-APIC irq_chip retrigger hook
To: Thomas Gleixner <tglx@linutronix.de>
References: <1484662432-13580-1-git-send-email-rruslich@cisco.com>
 <alpine.DEB.2.20.1701181144270.3464@nanos>
Cc: Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        x86@kernel.org, linux-kernel@vger.kernel.org,
        xe-linux-external@cisco.com
From: "Ruslan Ruslichenko -X (rruslich - GLOBALLOGIC INC at Cisco)" 
        <rruslich@cisco.com>
Message-ID: <3d22ad32-74c1-4be5-4086-686c34edf84b@cisco.com>
Date: Wed, 18 Jan 2017 16:26:14 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.5.1
MIME-Version: 1.0
In-Reply-To: <alpine.DEB.2.20.1701181144270.3464@nanos>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
X-Auto-Response-Suppress: DR, OOF, AutoReply
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 01/18/2017 12:46 PM, Thomas Gleixner wrote:
> On Tue, 17 Jan 2017, Ruslan Ruslichenko wrote:
>
>> After commit d32932d02e18  ("x86/irq: Convert IOAPIC to use hierarchical
>> irqdomain interfaces") IO-APIC is switched to hierarchical irqdomain
>> implementation. Also this patch removed irq_retrigger hook for IO-APIC
>> chip which seem to be wrong. Without this hook some edge-triggered irq's
>> might be lost, since kernel uses it to retrigger edge irq's triggered
>> while they are being handled or disabled by driver
> Restoring the callbacks is the right thing to do, but there is no problem
> because if the retrigger callback is empty then pending edge interrupts are
> resent by software. It's just less efficient, but not a issue.

Software resend will only work if CONFIG_HARDIRQS_SW_RESEND is enabled,
which is not selected for x86 architectures.

So it's good that patch now picked up.
> Thanks,
>
> 	tglx