From: Michael S. Tsirkin Date: Sun, 4 Jan 2015 15:28:27 +0000 (+0200) Subject: virtio_pci: document why we defer kfree X-Git-Tag: v3.4.107~94 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=39930a5de9598226b2dfd4920f251058045bf827;p=thirdparty%2Fkernel%2Fstable.git virtio_pci: document why we defer kfree 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 --- diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index c9c93e0dc5caf..cc56763ff96dc 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); }