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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 ED461CA9EA0 for ; Fri, 18 Oct 2019 16:47:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C959C2089C for ; Fri, 18 Oct 2019 16:47:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2439805AbfJRQr0 (ORCPT ); Fri, 18 Oct 2019 12:47:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57818 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728368AbfJRQr0 (ORCPT ); Fri, 18 Oct 2019 12:47:26 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C28CA328E; Fri, 18 Oct 2019 16:47:25 +0000 (UTC) Received: from thinkpad.redhat.com (ovpn-116-247.ams2.redhat.com [10.36.116.247]) by smtp.corp.redhat.com (Postfix) with ESMTP id 0A0915D713; Fri, 18 Oct 2019 16:47:19 +0000 (UTC) From: Laurent Vivier To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , Amit Shah , virtualization@lists.linux-foundation.org, Arnd Bergmann , "Michael S . Tsirkin" , Laurent Vivier Subject: [PATCH] virtio_console: allocate inbufs in add_port() only if it is needed Date: Fri, 18 Oct 2019 18:47:18 +0200 Message-Id: <20191018164718.15999-1-lvivier@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 18 Oct 2019 16:47:25 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When we hot unplug a virtserialport and then try to hot plug again, it fails: (qemu) chardev-add socket,id=serial0,path=/tmp/serial0,server,nowait (qemu) device_add virtserialport,bus=virtio-serial0.0,nr=2,\ chardev=serial0,id=serial0,name=serial0 (qemu) device_del serial0 (qemu) device_add virtserialport,bus=virtio-serial0.0,nr=2,\ chardev=serial0,id=serial0,name=serial0 kernel error: virtio-ports vport2p2: Error allocating inbufs qemu error: virtio-serial-bus: Guest failure in adding port 2 for device \ virtio-serial0.0 This happens because buffers for the in_vq are allocated when the port is added but are not released when the port is unplugged. They are only released when virtconsole is removed (see a7a69ec0d8e4) To avoid the problem and to be symmetric, we could allocate all the buffers in init_vqs() as they are released in remove_vqs(), but it sounds like a waste of memory. Rather than that, this patch changes add_port() logic to only allocate the buffers if the in_vq has available free slots. Fixes: a7a69ec0d8e4 ("virtio_console: free buffers after reset") Cc: mst@redhat.com Signed-off-by: Laurent Vivier --- drivers/char/virtio_console.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 7270e7b69262..77105166fe01 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -1421,12 +1421,17 @@ static int add_port(struct ports_device *portdev, u32 id) spin_lock_init(&port->outvq_lock); init_waitqueue_head(&port->waitqueue); - /* Fill the in_vq with buffers so the host can send us data. */ - nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock); - if (!nr_added_bufs) { - dev_err(port->dev, "Error allocating inbufs\n"); - err = -ENOMEM; - goto free_device; + /* if the in_vq has not already been filled (the port has already been + * used and unplugged), fill the in_vq with buffers so the host can + * send us data. + */ + if (port->in_vq->num_free != 0) { + nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock); + if (!nr_added_bufs) { + dev_err(port->dev, "Error allocating inbufs\n"); + err = -ENOMEM; + goto free_device; + } } if (is_rproc_serial(port->portdev->vdev)) -- 2.21.0