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 C4574C433EF for ; Sat, 16 Apr 2022 04:50:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230123AbiDPEwf (ORCPT ); Sat, 16 Apr 2022 00:52:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54554 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230081AbiDPEwZ (ORCPT ); Sat, 16 Apr 2022 00:52:25 -0400 Received: from mail-pl1-f175.google.com (mail-pl1-f175.google.com [209.85.214.175]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31F95641F; Fri, 15 Apr 2022 21:49:54 -0700 (PDT) Received: by mail-pl1-f175.google.com with SMTP id q3so8517980plg.3; Fri, 15 Apr 2022 21:49:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=n64Ceh0+mncTh8c+PN3WAxiVq0wOhX+10SaNJK7xeCg=; b=Jqnmzopz5ELeysnhdiaOIaA8G07f/4jdOqvoLHb6YcDLZs4tqvKQzagzV+wK86eQAL wtpzUZiHX7wnBd7mmAQ3l9jDVgBArNapaJGjtVWLCiousTou+ZM7HAX4luB1GxNDW9FI WKk6lcZctQhpWjAQJoBhcddHQHunG9yAQ4IeEmRAdUf19AJVF0NUF3/YHNmNgA9vo5vo xHzWWaIrJQeidPzeuSKLiggShjE5yoMh885s61e3/1ZnuHrSnxes6dE1L9RyT6CFWAfe fKouCfNGBfjtVNYJdgzwY4HJVX70mzWQEi2iYjiToDJuFjYGe4sTbovEQql3/gr58CKC T2PA== X-Gm-Message-State: AOAM531f0cmG9kg7wIGkZMEKfuxT+HlTcBT2JFcys3QIxQbFaCWvHQh2 KedyMGmSf07amDvT8+KztKc= X-Google-Smtp-Source: ABdhPJwT6to3858USQjNTK1oP4TKo79v1y7v98iKirBSDZhQhO7QnuXHQM8Wa7Lvk5eiXgmaG9AuCA== X-Received: by 2002:a17:90b:4c44:b0:1c7:1326:ec90 with SMTP id np4-20020a17090b4c4400b001c71326ec90mr7502827pjb.87.1650084593598; Fri, 15 Apr 2022 21:49:53 -0700 (PDT) Received: from ?IPV6:2601:647:4000:d7:feaa:14ff:fe9d:6dbd? ([2601:647:4000:d7:feaa:14ff:fe9d:6dbd]) by smtp.gmail.com with ESMTPSA id k4-20020a17090a3e8400b001cd37f6c0b7sm6129296pjc.46.2022.04.15.21.49.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 15 Apr 2022 21:49:52 -0700 (PDT) Message-ID: <3164cd23-28b5-e971-c7a9-1b565b344ed5@acm.org> Date: Fri, 15 Apr 2022 21:49:51 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH v4 1/1] scsi: Fix racing between dev init and dev reset Content-Language: en-US To: Alice Chao , jejb@linux.ibm.com, martin.petersen@oracle.com, matthias.bgg@gmail.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Cc: stanley.chu@mediatek.com, peter.wang@mediatek.com, chun-hung.wu@mediatek.com, powen.kao@mediatek.com, cc.chou@mediatek.com, chaotian.jing@mediatek.com, jiajie.hao@mediatek.com, qilin.tan@mediatek.com, lin.gui@mediatek.com, yanxu.wei@mediatek.com, wsd_upstream@mediatek.com References: <20220415061243.30229-2-alice.chao@mediatek.com> From: Bart Van Assche In-Reply-To: <20220415061243.30229-2-alice.chao@mediatek.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/14/22 23:12, Alice Chao wrote: > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 0a70aa763a96..abf9a71ed77c 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -2461,6 +2461,7 @@ static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt) > break; > case SDEV_EVT_POWER_ON_RESET_OCCURRED: > envp[idx++] = "SDEV_UA=POWER_ON_RESET_OCCURRED"; > + wait_event(sdev->host->host_wait, sdev->sdev_gendev.kobj.parent != NULL); > break; > default: > /* do nothing */ > diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c > index f4e6c68ac99e..431f229ac435 100644 > --- a/drivers/scsi/scsi_scan.c > +++ b/drivers/scsi/scsi_scan.c > @@ -1904,6 +1904,7 @@ static void do_scsi_scan_host(struct Scsi_Host *shost) > } else { > scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD, > SCAN_WILD_CARD, 0); > + wake_up(&shost->host_wait); > } > } The above patch can only work if scanning a host is followed by a POWER ON unit attention. I don't think that is guaranteed. Additionally, what will happen with the wait loop if the device generates a POWER on unit attention after the device has been removed from its parent? kobject_del() clears the parent pointer. device_del() calls kobject_del(). scsi_remove_device() calls device_del() before the request queue is destroyed. Thanks, Bart.