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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=ham 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 666BCC32771 for ; Thu, 16 Jan 2020 01:54:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B97F2084D for ; Thu, 16 Jan 2020 01:54:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730472AbgAPByO (ORCPT ); Wed, 15 Jan 2020 20:54:14 -0500 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]:39969 "EHLO out30-44.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729949AbgAPByO (ORCPT ); Wed, 15 Jan 2020 20:54:14 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04452;MF=zhangliguang@linux.alibaba.com;NM=1;PH=DS;RN=3;SR=0;TI=SMTPD_---0Tnr.RhS_1579139650; Received: from 30.5.115.118(mailfrom:zhangliguang@linux.alibaba.com fp:SMTPD_---0Tnr.RhS_1579139650) by smtp.aliyun-inc.com(127.0.0.1); Thu, 16 Jan 2020 09:54:11 +0800 Subject: Re: [PATCH 1/3] firmware: arm_sdei: fix possible deadlock To: James Morse Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <1577110975-54782-1-git-send-email-zhangliguang@linux.alibaba.com> From: =?UTF-8?B?5Lmx55+z?= Message-ID: Date: Thu, 16 Jan 2020 09:54:10 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: <1577110975-54782-1-git-send-email-zhangliguang@linux.alibaba.com> Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi James, Sorry for the late reply, this problem was found by code review. Thanks, luanshi ÔÚ 2019/12/23 22:22, luanshi дµÀ: > From: Liguang Zhang > > We call sdei_reregister_event() with sdei_list_lock held but > _sdei_event_register() and sdei_event_destroy() also acquires > sdei_list_lock thus creating A-A deadlock. > > Fixes: da351827240e ("firmware: arm_sdei: Add support for CPU and system power states") > Signed-off-by: Liguang Zhang > --- > drivers/firmware/arm_sdei.c | 17 ++++++++--------- > 1 file changed, 8 insertions(+), 9 deletions(-) > > diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c > index a479023..b122927 100644 > --- a/drivers/firmware/arm_sdei.c > +++ b/drivers/firmware/arm_sdei.c > @@ -651,20 +651,19 @@ static int sdei_reregister_event(struct sdei_event *event) > > lockdep_assert_held(&sdei_events_lock); > > - err = _sdei_event_register(event); > + err = sdei_api_event_register(event->event_num, > + sdei_entry_point, > + event->registered, > + SDEI_EVENT_REGISTER_RM_ANY, 0); > if (err) { > pr_err("Failed to re-register event %u\n", event->event_num); > - sdei_event_destroy(event); > + list_del(&event->list); > + kfree(event->registered); > return err; > } > > - if (event->reenable) { > - if (event->type == SDEI_EVENT_TYPE_SHARED) > - err = sdei_api_event_enable(event->event_num); > - else > - err = sdei_do_cross_call(_local_event_enable, event); > - } > - > + if (event->reenable) > + err = sdei_api_event_enable(event->event_num); > if (err) > pr_err("Failed to re-enable event %u\n", event->event_num); >