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 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 C390CC77B73 for ; Thu, 20 Apr 2023 11:44:00 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ppSgS-0004VN-NN; Thu, 20 Apr 2023 07:42:41 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ppSeb-0000Mq-6F for qemu-devel@nongnu.org; Thu, 20 Apr 2023 07:40:46 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ppSdf-0001ga-Gc for qemu-devel@nongnu.org; Thu, 20 Apr 2023 07:39:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681990740; 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=Qs0Wu6hxc7j58DwPPRdDhx+qIxo2MCSBXMmfJ14jr7A=; b=M168B0/OthBl40Mt0XIG47N+Kcmq6Jf00zsagz8mRe6jB4kzA7Cf5APLHcpnO9FmYiWtuf zltUAWKPsVLoxs0pp8k9CEDyParaJy7judu/yUjGPQYOE0vSDXYHPxYcUAf08d4e00TRjF NAm9s70I8BiBuu/gbI8FZSyda1/qPok= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-339-5QKxe0gLNiqnQQj1agtczQ-1; Thu, 20 Apr 2023 07:38:57 -0400 X-MC-Unique: 5QKxe0gLNiqnQQj1agtczQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 488F0280BF6C; Thu, 20 Apr 2023 11:38:56 +0000 (UTC) Received: from localhost (unknown [10.39.193.254]) by smtp.corp.redhat.com (Postfix) with ESMTP id 782302166B33; Thu, 20 Apr 2023 11:38:55 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: Peter Lieven , Stefan Hajnoczi , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Paolo Bonzini , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Xie Yongji , Juan Quintela , qemu-block@nongnu.org, Eduardo Habkost , Richard Henderson , David Woodhouse , Stefan Weil , Fam Zheng , Julia Suvorova , Ronnie Sahlberg , xen-devel@lists.xenproject.org, Hanna Reitz , "Dr. David Alan Gilbert" , eesposit@redhat.com, Kevin Wolf , Marcel Apfelbaum , Stefano Stabellini , Paul Durrant , Aarushi Mehta , "Michael S. Tsirkin" , Anthony Perard , "Richard W.M. Jones" , Coiby Xu , Stefano Garzarella Subject: [PATCH v3 16/20] virtio: make it possible to detach host notifier from any thread Date: Thu, 20 Apr 2023 07:37:28 -0400 Message-Id: <20230420113732.336620-17-stefanha@redhat.com> In-Reply-To: <20230420113732.336620-1-stefanha@redhat.com> References: <20230420113732.336620-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org virtio_queue_aio_detach_host_notifier() does two things: 1. It removes the fd handler from the event loop. 2. It processes the virtqueue one last time. The first step can be peformed by any thread and without taking the AioContext lock. The second step may need the AioContext lock (depending on the device implementation) and runs in the thread where request processing takes place. virtio-blk and virtio-scsi therefore call virtio_queue_aio_detach_host_notifier() from a BH that is scheduled in AioContext Scheduling a BH is undesirable for .drained_begin() functions. The next patch will introduce a .drained_begin() function that needs to call virtio_queue_aio_detach_host_notifier(). Move the virtqueue processing out to the callers of virtio_queue_aio_detach_host_notifier() so that the function can be called from any thread. This is in preparation for the next patch. Signed-off-by: Stefan Hajnoczi --- hw/block/dataplane/virtio-blk.c | 2 ++ hw/scsi/virtio-scsi-dataplane.c | 9 +++++++++ 2 files changed, 11 insertions(+) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index b28d81737e..bd7cc6e76b 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -286,8 +286,10 @@ static void virtio_blk_data_plane_stop_bh(void *opaque) for (i = 0; i < s->conf->num_queues; i++) { VirtQueue *vq = virtio_get_queue(s->vdev, i); + EventNotifier *host_notifier = virtio_queue_get_host_notifier(vq); virtio_queue_aio_detach_host_notifier(vq, s->ctx); + virtio_queue_host_notifier_read(host_notifier); } } diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c index 20bb91766e..81643445ed 100644 --- a/hw/scsi/virtio-scsi-dataplane.c +++ b/hw/scsi/virtio-scsi-dataplane.c @@ -71,12 +71,21 @@ static void virtio_scsi_dataplane_stop_bh(void *opaque) { VirtIOSCSI *s = opaque; VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s); + EventNotifier *host_notifier; int i; virtio_queue_aio_detach_host_notifier(vs->ctrl_vq, s->ctx); + host_notifier = virtio_queue_get_host_notifier(vs->ctrl_vq); + virtio_queue_host_notifier_read(host_notifier); + virtio_queue_aio_detach_host_notifier(vs->event_vq, s->ctx); + host_notifier = virtio_queue_get_host_notifier(vs->event_vq); + virtio_queue_host_notifier_read(host_notifier); + for (i = 0; i < vs->conf.num_queues; i++) { virtio_queue_aio_detach_host_notifier(vs->cmd_vqs[i], s->ctx); + host_notifier = virtio_queue_get_host_notifier(vs->cmd_vqs[i]); + virtio_queue_host_notifier_read(host_notifier); } } -- 2.39.2