From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752801AbbADQCl (ORCPT ); Sun, 4 Jan 2015 11:02:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46625 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752630AbbADQCg (ORCPT ); Sun, 4 Jan 2015 11:02:36 -0500 Date: Sun, 4 Jan 2015 18:02:27 +0200 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: sasha.levin@oracle.com, virtualization@lists.linux-foundation.org, stable@vger.kernel.org, Rusty Russell Subject: [PATCH 3/3] virtio_pci: document why we defer kfree Message-ID: <1420386340-7719-4-git-send-email-mst@redhat.com> References: <1420386340-7719-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1420386340-7719-1-git-send-email-mst@redhat.com> X-Mutt-Fcc: =sent Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The reason we defer kfree until release function is because it's a general rule for kobjects: kfree of the reference counter itself is only legal in the release function. Previous patch didn't make this clear, document this in code. Cc: stable@vger.kernel.org Signed-off-by: Michael S. Tsirkin --- drivers/virtio/virtio_pci_legacy.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c index 4beaee3..a5486e6 100644 --- a/drivers/virtio/virtio_pci_legacy.c +++ b/drivers/virtio/virtio_pci_legacy.c @@ -216,6 +216,9 @@ static void virtio_pci_release_dev(struct device *_d) struct virtio_device *vdev = dev_to_virtio(_d); struct virtio_pci_device *vp_dev = to_vp_device(vdev); + /* As struct device is a kobject, it's not safe to + * free the memory (including the reference counter itself) + * until it's release callback. */ kfree(vp_dev); } -- MST