Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760033AbZKZA0e (ORCPT ); Wed, 25 Nov 2009 19:26:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760025AbZKZA0d (ORCPT ); Wed, 25 Nov 2009 19:26:33 -0500 Received: from bhuna.collabora.co.uk ([93.93.128.226]:41575 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759662AbZKZA0N (ORCPT ); Wed, 25 Nov 2009 19:26:13 -0500 From: Ian Molton Cc: rusty@rustcorp.com.au, linux-kernel@vger.kernel.org, mpm@selenic.com, Ian Molton Subject: [PATCH 2/2] virtio: Convert virtio-rng to the new API Date: Thu, 26 Nov 2009 00:25:27 +0000 Message-Id: <1259195127-20086-3-git-send-email-ian.molton@collabora.co.uk> X-Mailer: git-send-email 1.6.5 In-Reply-To: <1259195127-20086-2-git-send-email-ian.molton@collabora.co.uk> References: <1259177252.2858.17.camel@calx> <1259195127-20086-1-git-send-email-ian.molton@collabora.co.uk> <1259195127-20086-2-git-send-email-ian.molton@collabora.co.uk> To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4335 Lines: 168 This patch converts virtio-rng to the new hw_rng API. In the process it fixes a previously untriggered buffering bug where the buffer is not drained correctly if it has a non-multiple-of-4 length. Performance has improved under qemu-kvm testing also. Signed-off-by: Ian Molton --- drivers/char/hw_random/virtio-rng.c | 79 ++++++++++++---------------------- 1 files changed, 28 insertions(+), 51 deletions(-) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index 915157f..76d00c4 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -16,6 +16,7 @@ * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ + #include #include #include @@ -23,78 +24,65 @@ #include #include -/* The host will fill any buffer we give it with sweet, sweet randomness. We - * give it 64 bytes at a time, and the hwrng framework takes it 4 bytes at a - * time. */ -#define RANDOM_DATA_SIZE 64 - static struct virtqueue *vq; -static u32 *random_data; -static unsigned int data_left; +static unsigned int data_avail; static DECLARE_COMPLETION(have_data); +static int busy; + +/* The host will fill any buffer we give it with sweet, sweet randomness. */ static void random_recv_done(struct virtqueue *vq) { - unsigned int len; - /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */ - if (!vq->vq_ops->get_buf(vq, &len)) + if (!vq->vq_ops->get_buf(vq, &data_avail)) return; - data_left += len; complete(&have_data); } -static void register_buffer(void) +static void register_buffer(u8 *buf, size_t size) { struct scatterlist sg; - sg_init_one(&sg, random_data+data_left, RANDOM_DATA_SIZE-data_left); + sg_init_one(&sg, buf, size); + /* There should always be room for one buffer. */ - if (vq->vq_ops->add_buf(vq, &sg, 0, 1, random_data) < 0) + if (vq->vq_ops->add_buf(vq, &sg, 0, 1, buf) < 0) BUG(); + vq->vq_ops->kick(vq); } -/* At least we don't udelay() in a loop like some other drivers. */ -static int virtio_data_present(struct hwrng *rng, int wait) +static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) { - if (data_left >= sizeof(u32)) - return 1; -again: + if (!busy) { + busy = 1; + init_completion(&have_data); + register_buffer(buf, size); + } + if (!wait) return 0; wait_for_completion(&have_data); - /* Not enough? Re-register. */ - if (unlikely(data_left < sizeof(u32))) { - register_buffer(); - goto again; - } + busy = 0; - return 1; + return data_avail; } -/* virtio_data_present() must have succeeded before this is called. */ -static int virtio_data_read(struct hwrng *rng, u32 *data) +static void virtio_cleanup(struct hwrng *rng) { - BUG_ON(data_left < sizeof(u32)); - data_left -= sizeof(u32); - *data = random_data[data_left / 4]; - - if (data_left < sizeof(u32)) { - init_completion(&have_data); - register_buffer(); - } - return sizeof(*data); + if (busy) + wait_for_completion(&have_data); } + static struct hwrng virtio_hwrng = { - .name = "virtio", - .data_present = virtio_data_present, - .data_read = virtio_data_read, + .name = "virtio", + .cleanup = virtio_cleanup, + .read = virtio_read, }; static int virtrng_probe(struct virtio_device *vdev) @@ -112,7 +100,6 @@ static int virtrng_probe(struct virtio_device *vdev) return err; } - register_buffer(); return 0; } @@ -138,21 +125,11 @@ static struct virtio_driver virtio_rng = { static int __init init(void) { - int err; - - random_data = kmalloc(RANDOM_DATA_SIZE, GFP_KERNEL); - if (!random_data) - return -ENOMEM; - - err = register_virtio_driver(&virtio_rng); - if (err) - kfree(random_data); - return err; + return register_virtio_driver(&virtio_rng); } static void __exit fini(void) { - kfree(random_data); unregister_virtio_driver(&virtio_rng); } module_init(init); -- 1.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/