Return-Path: From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, "Michael S. Tsirkin" , Zefan Li Subject: [PATCH 3.4 084/176] virtio_pci: document why we defer kfree Date: Thu, 9 Apr 2015 16:45:32 +0800 Message-Id: <1428569224-23820-84-git-send-email-lizf@kernel.org> In-Reply-To: <1428569028-23762-1-git-send-email-lizf@kernel.org> References: <1428569028-23762-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: From: "Michael S. Tsirkin" 3.4.107-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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 [lizf: Backported to 3.4: adjust filename] Signed-off-by: Zefan Li --- 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 c9c93e0..cc56763 100644 --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c @@ -627,6 +627,9 @@ 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