From patchwork Fri Sep 9 20:34:21 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 9324353 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B28CA60231 for ; Fri, 9 Sep 2016 20:43:34 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A53A22A018 for ; Fri, 9 Sep 2016 20:43:34 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 98C582A01B; Fri, 9 Sep 2016 20:43:34 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 1C5492A018 for ; Fri, 9 Sep 2016 20:43:34 +0000 (UTC) Received: from localhost ([::1]:60124 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1biSe4-0005Yz-OD for patchwork-qemu-devel@patchwork.kernel.org; Fri, 09 Sep 2016 16:43:32 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55758) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1biSVE-0005zP-PL for qemu-devel@nongnu.org; Fri, 09 Sep 2016 16:34:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1biSVD-0005Pa-RX for qemu-devel@nongnu.org; Fri, 09 Sep 2016 16:34:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49726) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1biSVD-0005PP-MB; Fri, 09 Sep 2016 16:34:23 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4AB30C00067E; Fri, 9 Sep 2016 20:34:23 +0000 (UTC) Received: from redhat.com (vpn-62-83.rdu2.redhat.com [10.10.62.83]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id u89KYMBK028652; Fri, 9 Sep 2016 16:34:22 -0400 Date: Fri, 9 Sep 2016 23:34:21 +0300 From: "Michael S. Tsirkin" To: qemu-devel@nongnu.org Message-ID: <1473453215-7556-7-git-send-email-mst@redhat.com> References: <1473453215-7556-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1473453215-7556-1-git-send-email-mst@redhat.com> X-Mutt-Fcc: =sent X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Fri, 09 Sep 2016 20:34:23 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 06/14] virtio: zero vq->inuse in virtio_reset() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Ladi Prosek , qemu-stable , Stefan Hajnoczi Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Stefan Hajnoczi vq->inuse must be zeroed upon device reset like most other virtqueue fields. In theory, virtio_reset() just needs assert(vq->inuse == 0) since devices must clean up in-flight requests during reset (requests cannot not be leaked!). In practice, it is difficult to achieve vq->inuse == 0 across reset because balloon, blk, 9p, etc implement various different strategies for cleaning up requests. Most devices call g_free(elem) directly without telling virtio.c that the VirtQueueElement is cleaned up. Therefore vq->inuse is not decremented during reset. This patch zeroes vq->inuse and trusts that devices are not leaking VirtQueueElements across reset. I will send a follow-up series that refactors request life-cycle across all devices and converts vq->inuse = 0 into assert(vq->inuse == 0) but this more invasive approach is not appropriate for stable trees. Signed-off-by: Stefan Hajnoczi Cc: qemu-stable Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Reviewed-by: Ladi Prosek --- hw/virtio/virtio.c | 1 + 1 file changed, 1 insertion(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 74c085c..e8a13a5 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -822,6 +822,7 @@ void virtio_reset(void *opaque) vdev->vq[i].signalled_used_valid = false; vdev->vq[i].notification = true; vdev->vq[i].vring.num = vdev->vq[i].vring.num_default; + vdev->vq[i].inuse = 0; } }