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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6DB2BC6FA8F for ; Tue, 29 Aug 2023 09:06:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232439AbjH2JFv (ORCPT ); Tue, 29 Aug 2023 05:05:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46624 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234434AbjH2JF1 (ORCPT ); Tue, 29 Aug 2023 05:05:27 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A62B2139 for ; Tue, 29 Aug 2023 02:05:22 -0700 (PDT) Received: from dggpeml500019.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4RZhHq6s2nzJsFB; Tue, 29 Aug 2023 17:01:43 +0800 (CST) Received: from [10.67.121.58] (10.67.121.58) by dggpeml500019.china.huawei.com (7.185.36.137) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Tue, 29 Aug 2023 17:05:20 +0800 Message-ID: <087f1c16-7e40-9801-e63d-72a0135d99a4@hisilicon.com> Date: Tue, 29 Aug 2023 17:05:20 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.3.2 Subject: Re: [PATCH] irqdomain: Fix driver re-inserting failures when IRQs not being freed completely To: Thomas Gleixner , CC: , , , , , , References: <20230720122429.4123447-1-zhanjie9@hisilicon.com> <87msyfatoq.ffs@tglx> From: Jie Zhan In-Reply-To: <87msyfatoq.ffs@tglx> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.121.58] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpeml500019.china.huawei.com (7.185.36.137) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/08/2023 02:00, Thomas Gleixner wrote: > On Thu, Jul 20 2023 at 20:24, Jie Zhan wrote: >> Since commit 4615fbc3788d ("genirq/irqdomain: Don't try to free an >> interrupt that has no mapping"), we have found failures when >> re-inserting some specific drivers: >> >> [root@localhost ~]# rmmod hisi_sas_v3_hw >> [root@localhost ~]# modprobe hisi_sas_v3_hw >> [ 1295.622525] hisi_sas_v3_hw: probe of 0000:30:04.0 failed with error -2 >> >> This comes from the case where some IRQs allocated from a low-level domain, >> e.g. GIC ITS, are not freed completely, leaving some leaked. Thus, the next >> driver insertion fails to get the same number of IRQs because some IRQs are >> still occupied. > Why? > >> Free a contiguous group of IRQs in one go to fix this issue. > Again why? > >> @@ -1445,13 +1445,24 @@ static void irq_domain_free_irqs_hierarchy(struct irq_domain *domain, >> unsigned int nr_irqs) >> { >> unsigned int i; >> + int n; >> >> if (!domain->ops->free) >> return; >> >> for (i = 0; i < nr_irqs; i++) { >> - if (irq_domain_get_irq_data(domain, irq_base + i)) >> - domain->ops->free(domain, irq_base + i, 1); >> + /* Find the largest possible span of IRQs to free in one go */ >> + for (n = 0; >> + ((i + n) < nr_irqs) && >> + (irq_domain_get_irq_data(domain, irq_base + i + n)); >> + n++) >> + ; > For one this is unreadable gunk. But what's worse it still does not > explain what this is solving. > > It's completely sensible to expect that freeing interrupts in a range > one by one just works. > > So why do we need to work around an obvious low level failure in the > core code? > > Thanks, > > tglx Hi Thomas, Many thanks for taking a look. I believe this patch should be completely reworked as it has caused many questions in the first place --- it's not explaining itself well. Please ignore this one now. The story of the problem is a bit long and complicated. The previous disscusion can be found in the link attached. Jie