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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 623ECC433E0 for ; Sun, 14 Mar 2021 09:16:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 276BD64DAF for ; Sun, 14 Mar 2021 09:16:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234806AbhCNJQF (ORCPT ); Sun, 14 Mar 2021 05:16:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43194 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233268AbhCNJP7 (ORCPT ); Sun, 14 Mar 2021 05:15:59 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79E2AC061574; Sun, 14 Mar 2021 01:15:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=TWvz+uUE9a8YWLli6MgkhitIFLF6au76H0ezmr1npJk=; b=Lprx96r9Np8HbSg8L5S4AMBWtG jIiZN9+w3VTnRd7NrppfxjEuT7d4ADdg6sKsGNORq59Kvey6j5GIkDJPiNBsyc9gs+6B+tQX1w7Cl l6fqa+gvvRJ3SYay50wLGDKA1tp16eqNOHF/7x4I0wgsEIIBkPv1A5bcR9nCSV/UskeRkLEt3n172 V7k2JYe13FwzqP+8gY7bNx6ajhG/8M5jnqKuk/2wFU+UOf/KnPdwdmGaVy7J4NDvJvefStwdy4b3B zY56/bHFCyQKgLWiecDv9ePFDnOEf2teKljAQ1vnn8EOzkxgRZOie+7WJOmqlHj/FpFdb/KVSWFKu +tuwHmwg==; Received: from hch by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lLMpd-00Fpf6-5r; Sun, 14 Mar 2021 09:14:55 +0000 Date: Sun, 14 Mar 2021 09:14:41 +0000 From: Christoph Hellwig To: Mike Snitzer Cc: Sergei Shtepa , Christoph Hellwig , Alasdair Kergon , Hannes Reinecke , Jens Axboe , dm-devel@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, pavel.tide@veeam.com Subject: Re: [PATCH v7 1/3] block: add blk_mq_is_queue_frozen() Message-ID: <20210314091441.GA3773360@infradead.org> References: <1615563895-28565-1-git-send-email-sergei.shtepa@veeam.com> <1615563895-28565-2-git-send-email-sergei.shtepa@veeam.com> <20210312190641.GA2550@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210312190641.GA2550@redhat.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, Mar 12, 2021 at 02:06:41PM -0500, Mike Snitzer wrote: > This is returning a frozen state that is immediately stale. I don't > think any code calling this is providing the guarantees you think it > does due to the racey nature of this state once the mutex is dropped. The code only uses it for asserts in the form of WARN_ONs. 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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 B6E4FC433E0 for ; Sun, 14 Mar 2021 09:30:16 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4776B64EBA for ; Sun, 14 Mar 2021 09:30:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4776B64EBA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=dm-devel-bounces@redhat.com Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-270-WdvaYUgNMKSww3hnLow87g-1; Sun, 14 Mar 2021 05:30:12 -0400 X-MC-Unique: WdvaYUgNMKSww3hnLow87g-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 435A1817469; Sun, 14 Mar 2021 09:30:08 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 198816E407; Sun, 14 Mar 2021 09:30:08 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 086F218006D9; Sun, 14 Mar 2021 09:30:06 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 12E9U4Mr023603 for ; Sun, 14 Mar 2021 05:30:04 -0400 Received: by smtp.corp.redhat.com (Postfix) id 7BDF02026D6A; Sun, 14 Mar 2021 09:30:04 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast03.extmail.prod.ext.rdu2.redhat.com [10.11.55.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 76FB42026D60 for ; Sun, 14 Mar 2021 09:30:00 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D82C4811E7A for ; Sun, 14 Mar 2021 09:30:00 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-423-XeinXoZPNfe3OW-Qxbivdg-1; Sun, 14 Mar 2021 05:29:58 -0400 X-MC-Unique: XeinXoZPNfe3OW-Qxbivdg-1 Received: from hch by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lLMpd-00Fpf6-5r; Sun, 14 Mar 2021 09:14:55 +0000 Date: Sun, 14 Mar 2021 09:14:41 +0000 From: Christoph Hellwig To: Mike Snitzer Message-ID: <20210314091441.GA3773360@infradead.org> References: <1615563895-28565-1-git-send-email-sergei.shtepa@veeam.com> <1615563895-28565-2-git-send-email-sergei.shtepa@veeam.com> <20210312190641.GA2550@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210312190641.GA2550@redhat.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-loop: dm-devel@redhat.com Cc: Jens Axboe , linux-block@vger.kernel.org, linux-api@vger.kernel.org, pavel.tide@veeam.com, linux-kernel@vger.kernel.org, Christoph Hellwig , dm-devel@redhat.com, Sergei Shtepa , Alasdair Kergon Subject: Re: [dm-devel] [PATCH v7 1/3] block: add blk_mq_is_queue_frozen() X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri, Mar 12, 2021 at 02:06:41PM -0500, Mike Snitzer wrote: > This is returning a frozen state that is immediately stale. I don't > think any code calling this is providing the guarantees you think it > does due to the racey nature of this state once the mutex is dropped. The code only uses it for asserts in the form of WARN_ONs. -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel