From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755344AbbBSBA3 (ORCPT ); Wed, 18 Feb 2015 20:00:29 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:35412 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753668AbbBSAeC (ORCPT ); Wed, 18 Feb 2015 19:34:02 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: "Michael S. Tsirkin" , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 028/103] virtio_pci: document why we defer kfree Date: Wed, 18 Feb 2015 16:31:55 -0800 Message-Id: <1424305990-17983-29-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1424305990-17983-1-git-send-email-kamal@canonical.com> References: <1424305990-17983-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11-ckt16 -stable review patch. If anyone has any objections, please let me know. ------------------ From: "Michael S. Tsirkin" commit a1eb03f546d651a8f39c7d0692b1f7f5b4e7e3cd upstream. 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. Signed-off-by: Michael S. Tsirkin Signed-off-by: Kamal Mostafa --- drivers/virtio/virtio_pci.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index 8a430b2..6b35f925 100644 --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c @@ -673,6 +673,9 @@ 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); } -- 1.9.1