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 05BACC61D85 for ; Thu, 23 Nov 2023 19:50:56 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r6Fho-00026e-5n; Thu, 23 Nov 2023 14:49:44 -0500 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 1r6Fhn-00022d-DO for qemu-devel@nongnu.org; Thu, 23 Nov 2023 14:49:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r6Fhl-0000dI-Up for qemu-devel@nongnu.org; Thu, 23 Nov 2023 14:49:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700768981; 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=05/vyUzyQyx9iVyx5FvuHnsTh61cU0kKMNchw8eSi0U=; b=Hokv3ITAS3/uh7Wx1yFmPmw9yT8y/Hr4a19CnCso7njDKjrPspXCt2/jAzO3JeEzrXTznw 1McC8WPGFyGQNpXTYJKJLXjzPovS9y0+6GIrzIY6Q4gpkKmWsXVnHiTfQieCccdgBHNJhT /JXvvHclmMUe0C6SgKKeHrPIGwGrTnM= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-680-7W0mDJC0NbCsVGPebA79SA-1; Thu, 23 Nov 2023 14:49:39 -0500 X-MC-Unique: 7W0mDJC0NbCsVGPebA79SA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 845173801F68; Thu, 23 Nov 2023 19:49:39 +0000 (UTC) Received: from localhost (unknown [10.39.192.72]) by smtp.corp.redhat.com (Postfix) with ESMTP id DF438C15881; Thu, 23 Nov 2023 19:49:38 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: "Michael S. Tsirkin" , David Hildenbrand , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Peter Xu , Paolo Bonzini , Fam Zheng , Stefan Hajnoczi Subject: [PATCH 2/4] virtio-scsi: don't lock AioContext around virtio_queue_aio_attach_host_notifier() Date: Thu, 23 Nov 2023 14:49:29 -0500 Message-ID: <20231123194931.171598-3-stefanha@redhat.com> In-Reply-To: <20231123194931.171598-1-stefanha@redhat.com> References: <20231123194931.171598-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.133.124; 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=-0.058, 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham 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_attach_host_notifier() does not require the AioContext lock. Stop taking the lock and remember add an explicit smp_wmb() because we were relying on the implicit barrier in the AioContext lock before. Signed-off-by: Stefan Hajnoczi --- hw/scsi/virtio-scsi-dataplane.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c index 1e684beebe..135e23fe54 100644 --- a/hw/scsi/virtio-scsi-dataplane.c +++ b/hw/scsi/virtio-scsi-dataplane.c @@ -149,23 +149,17 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev) memory_region_transaction_commit(); - /* - * These fields are visible to the IOThread so we rely on implicit barriers - * in aio_context_acquire() on the write side and aio_notify_accept() on - * the read side. - */ s->dataplane_starting = false; s->dataplane_started = true; + smp_wmb(); /* paired with aio_notify_accept() */ if (s->bus.drain_count == 0) { - aio_context_acquire(s->ctx); virtio_queue_aio_attach_host_notifier(vs->ctrl_vq, s->ctx); virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq, s->ctx); for (i = 0; i < vs->conf.num_queues; i++) { virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], s->ctx); } - aio_context_release(s->ctx); } return 0; -- 2.42.0