Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936213AbaFJAbz (ORCPT ); Mon, 9 Jun 2014 20:31:55 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58627 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934550AbaFJAWq (ORCPT ); Mon, 9 Jun 2014 20:22:46 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, FuXiangChun , Amit Shah , Wanlong Gao , Asias He , Rusty Russell , Ben Hutchings , Yijing Wang Subject: [PATCH 3.4 53/88] virtio: console: add locking around c_ovq operations Date: Mon, 9 Jun 2014 17:25:03 -0700 Message-Id: <20140610002426.274754437@linuxfoundation.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <20140610002424.500996570@linuxfoundation.org> References: <20140610002424.500996570@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Amit Shah commit 9ba5c80b1aea8648a3efe5f22dc1f7cacdfbeeb8 upstream. When multiple ovq operations are being performed (lots of open/close operations on virtio_console fds), the __send_control_msg() function can get confused without locking. A simple recipe to cause badness is: * create a QEMU VM with two virtio-serial ports * in the guest, do while true;do echo abc >/dev/vport0p1;done while true;do echo edf >/dev/vport0p2;done In one run, this caused a panic in __send_control_msg(). In another, I got virtio_console virtio0: control-o:id 0 is not a head! This also results repeated messages similar to these on the host: qemu-kvm: virtio-serial-bus: Unexpected port id 478762112 for device virtio-serial-bus.0 qemu-kvm: virtio-serial-bus: Unexpected port id 478762368 for device virtio-serial-bus.0 Reported-by: FuXiangChun Signed-off-by: Amit Shah Reviewed-by: Wanlong Gao Reviewed-by: Asias He Signed-off-by: Rusty Russell [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings [wyj: Backported to 3.4: adjust context] Signed-off-by: Yijing Wang Signed-off-by: Greg Kroah-Hartman --- drivers/char/virtio_console.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -132,6 +132,7 @@ struct ports_device { /* To protect the vq operations for the control channel */ spinlock_t c_ivq_lock; + spinlock_t c_ovq_lock; /* The current config space is stored here */ struct virtio_console_config config; @@ -460,11 +461,14 @@ static ssize_t __send_control_msg(struct vq = portdev->c_ovq; sg_init_one(sg, &cpkt, sizeof(cpkt)); + + spin_lock(&portdev->c_ovq_lock); if (virtqueue_add_buf(vq, sg, 1, 0, &cpkt, GFP_ATOMIC) >= 0) { virtqueue_kick(vq); while (!virtqueue_get_buf(vq, &len)) cpu_relax(); } + spin_unlock(&portdev->c_ovq_lock); return 0; } @@ -1752,6 +1756,7 @@ static int __devinit virtcons_probe(stru unsigned int nr_added_bufs; spin_lock_init(&portdev->c_ivq_lock); + spin_lock_init(&portdev->c_ovq_lock); INIT_WORK(&portdev->control_work, &control_work_handler); nr_added_bufs = fill_queue(portdev->c_ivq, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/