From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40720) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YUK43-00074m-Eh for qemu-devel@nongnu.org; Sat, 07 Mar 2015 14:07:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YUK40-0000u1-7p for qemu-devel@nongnu.org; Sat, 07 Mar 2015 14:07:07 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42625) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YUK40-0000tw-0F for qemu-devel@nongnu.org; Sat, 07 Mar 2015 14:07:04 -0500 Date: Sat, 7 Mar 2015 20:06:56 +0100 From: "Michael S. Tsirkin" Message-ID: <1425754898-32707-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [Qemu-devel] [PATCH] virtio_rpmsg: set DRIVER_OK before using device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: linux-kernel@vger.kernel.org Cc: Ohad Ben-Cohen , Rusty Russell , qemu-devel@nongnu.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org virtio spec requires that all drivers set DRIVER_OK before using devices. While rpmsg isn't yet included in the virtio 1 spec, previous spec versions also required this. virtio rpmsg violates this rule: is calls kick before setting DRIVER_OK. The fix isn't trivial since simply calling virtio_device_ready earlier would mean we might get an interrupt in parallel with adding buffers. Instead, split kick out to prepare+notify calls. prepare before virtio_device_ready - when we know we won't get interrupts. notify right afterwards. Signed-off-by: Michael S. Tsirkin --- Note: compile-tested only. drivers/rpmsg/virtio_rpmsg_bus.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c index 92f6af6..73354ee 100644 --- a/drivers/rpmsg/virtio_rpmsg_bus.c +++ b/drivers/rpmsg/virtio_rpmsg_bus.c @@ -951,6 +951,7 @@ static int rpmsg_probe(struct virtio_device *vdev) void *bufs_va; int err = 0, i; size_t total_buf_space; + bool notify; vrp = kzalloc(sizeof(*vrp), GFP_KERNEL); if (!vrp) @@ -1030,8 +1031,22 @@ static int rpmsg_probe(struct virtio_device *vdev) } } + /* + * Prepare to kick but don't notify yet - we can't do this before + * device is ready. + */ + notify = virtqueue_kick_prepare(vrp->rvq); + + /* From this point on, we can notify and get callbacks. */ + virtio_device_ready(vdev); + /* tell the remote processor it can start sending messages */ - virtqueue_kick(vrp->rvq); + /* + * this might be concurrent with callbacks, but we are only + * doing notify, not a full kick here, so that's ok. + */ + if (notify) + virtqueue_notify(vrp->rvq); dev_info(&vdev->dev, "rpmsg host is online\n"); -- MST