From patchwork Wed Jun 15 15:51:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 12882676 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5F6B4C43334 for ; Wed, 15 Jun 2022 16:17:38 +0000 (UTC) Received: from localhost ([::1]:49420 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1o1Vi2-0006NC-Pq for qemu-devel@archiver.kernel.org; Wed, 15 Jun 2022 12:17:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44574) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o1VNa-0007OT-JZ for qemu-devel@nongnu.org; Wed, 15 Jun 2022 11:56:26 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:48539) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1o1VNZ-00080v-38 for qemu-devel@nongnu.org; Wed, 15 Jun 2022 11:56:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655308584; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=L5WzAuRIfjEYiaj3Lr/Q6liAFoL1wImF0/tiaZCofhU=; b=IYVblE7Pj3A59FIXEq5A29tSr3v7ogVFzvgGdZoXKwTYZ7rgmlqJgIWlnyPOLbtbfVmTTx QkfDxA+4mvU3KyBiaIWSX8Yo0vv4RXnaLFwQ3gIMb5aM+jzHB/91KT14/oLd/ipQYjtQ9Z Qm4UdKASklnSQISDSTQX2QLgJDfupHY= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-599-icbSYWUgM26YFzGsDv6ZVA-1; Wed, 15 Jun 2022 11:54:41 -0400 X-MC-Unique: icbSYWUgM26YFzGsDv6ZVA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E8C1B824061; Wed, 15 Jun 2022 15:54:39 +0000 (UTC) Received: from localhost (unknown [10.39.192.100]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8497F492CA6; Wed, 15 Jun 2022 15:54:39 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Thomas Huth , Jagannathan Raman , Aarushi Mehta , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= , Elena Ufimtseva , Marcel Apfelbaum , Stefan Hajnoczi , Laurent Vivier , , "Dr. David Alan Gilbert" , Richard Henderson , virtio-fs@redhat.com, Hanna Reitz , David Hildenbrand , =?utf-8?q?Alex_Benn=C3=A9e?= , Eric Blake , Kevin Wolf , =?utf-8?q?Da?= =?utf-8?q?niel_P=2E_Berrang=C3=A9?= , Beraldo Leal , Peter Xu , Eduardo Habkost , Qiuhao Li , Paolo Bonzini , Markus Armbruster , Bandan Das , "Michael S. Tsirkin" , Stefano Garzarella , Alexander Bulekov , Julia Suvorova , Darren Kenny , Wainer dos Santos Moschetta , John G Johnson , Nikolay Tenev Subject: [PULL 17/18] linux-aio: fix unbalanced plugged counter in laio_io_unplug() Date: Wed, 15 Jun 2022 16:51:28 +0100 Message-Id: <20220615155129.1025811-18-stefanha@redhat.com> In-Reply-To: <20220615155129.1025811-1-stefanha@redhat.com> References: <20220615155129.1025811-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Every laio_io_plug() call has a matching laio_io_unplug() call. There is a plugged counter that tracks the number of levels of plugging and allows for nesting. The plugged counter must reflect the balance between laio_io_plug() and laio_io_unplug() calls accurately. Otherwise I/O stalls occur since io_submit(2) calls are skipped while plugged. Reported-by: Nikolay Tenev Signed-off-by: Stefan Hajnoczi Reviewed-by: Stefano Garzarella Message-id: 20220609164712.1539045-2-stefanha@redhat.com Cc: Stefano Garzarella Fixes: 68d7946648 ("linux-aio: add `dev_max_batch` parameter to laio_io_unplug()") [Stefano Garzarella suggested adding a Fixes tag. --Stefan] Signed-off-by: Stefan Hajnoczi --- block/linux-aio.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/block/linux-aio.c b/block/linux-aio.c index 4c423fcccf..6078da7e42 100644 --- a/block/linux-aio.c +++ b/block/linux-aio.c @@ -363,8 +363,10 @@ void laio_io_unplug(BlockDriverState *bs, LinuxAioState *s, uint64_t dev_max_batch) { assert(s->io_q.plugged); + s->io_q.plugged--; + if (s->io_q.in_queue >= laio_max_batch(s, dev_max_batch) || - (--s->io_q.plugged == 0 && + (!s->io_q.plugged && !s->io_q.blocked && !QSIMPLEQ_EMPTY(&s->io_q.pending))) { ioq_submit(s); }