Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753800AbbBSNxg (ORCPT ); Thu, 19 Feb 2015 08:53:36 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:39393 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932378AbbBSNxa (ORCPT ); Thu, 19 Feb 2015 08:53:30 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Sasha Levin , "Michael S. Tsirkin" , Luis Henriques Subject: [PATCH 3.16.y-ckt 57/58] virtio_pci: defer kfree until release callback Date: Thu, 19 Feb 2015 13:52:27 +0000 Message-Id: <1424353948-31863-58-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1424353948-31863-1-git-send-email-luis.henriques@canonical.com> References: <1424353948-31863-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2392 Lines: 71 3.16.7-ckt7 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Sasha Levin commit 63bd62a08ca45a0c804c3c89777edc7f76a2d6da upstream. A struct device which has just been unregistered can live on past the point at which a driver decides to drop it's initial reference to the kobject gained on allocation. This implies that when releasing a virtio device, we can't free a struct virtio_device until the underlying struct device has been released, which might not happen immediately on device_unregister(). Unfortunately, this is exactly what virtio pci does: it has an empty release callback, and frees memory immediately after unregistering the device. This causes an easy to reproduce crash if CONFIG_DEBUG_KOBJECT_RELEASE it enabled. To fix, free the memory only once we know the device is gone in the release callback. Signed-off-by: Sasha Levin Signed-off-by: Michael S. Tsirkin [ luis: backported to 3.16: - file rename: virtio_pci_legacy.c -> virtio_pci.c ] Signed-off-by: Luis Henriques --- drivers/virtio/virtio_pci.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index 50c8ad598b49..a46570005a98 100644 --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c @@ -668,11 +668,10 @@ static const struct virtio_config_ops virtio_pci_config_ops = { static void virtio_pci_release_dev(struct device *_d) { - /* - * No need for a release method as we allocate/free - * all devices together with the pci devices. - * Provide an empty one to avoid getting a warning from core. - */ + struct virtio_device *vdev = dev_to_virtio(_d); + struct virtio_pci_device *vp_dev = to_vp_device(vdev); + + kfree(vp_dev); } /* the PCI probing function */ @@ -760,7 +759,6 @@ static void virtio_pci_remove(struct pci_dev *pci_dev) pci_iounmap(pci_dev, vp_dev->ioaddr); pci_release_regions(pci_dev); pci_disable_device(pci_dev); - kfree(vp_dev); } #ifdef CONFIG_PM_SLEEP -- 2.1.4 -- 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/