From 119d5897cc5f9f73e352a1c647d21b9d506b8c0a Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Fri, 2 Jan 2015 14:47:40 -0500 Subject: [PATCH 1/1] virtio_pci: defer kfree until release callback 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 [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings --- 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 03d1984bd363..65c907dc354e 100644 --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c @@ -612,11 +612,10 @@ static 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 */ @@ -704,7 +703,6 @@ static void __devexit 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 -- 2.30.2