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hwrng: virtio-rng - Convert to new API
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 <ian.molton@collabora.co.uk> Acked-by: Matt Mackall <mpm@selenic.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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parent
8386324381
commit
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1 changed files with 27 additions and 51 deletions
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@ -16,6 +16,7 @@
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <linux/err.h>
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#include <linux/hw_random.h>
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#include <linux/scatterlist.h>
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@ -23,78 +24,64 @@
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#include <linux/virtio.h>
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#include <linux/virtio_rng.h>
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/* The host will fill any buffer we give it with sweet, sweet randomness. We
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* give it 64 bytes at a time, and the hwrng framework takes it 4 bytes at a
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* time. */
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#define RANDOM_DATA_SIZE 64
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static struct virtqueue *vq;
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static u32 *random_data;
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static unsigned int data_left;
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static unsigned int data_avail;
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static DECLARE_COMPLETION(have_data);
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static bool busy;
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static void random_recv_done(struct virtqueue *vq)
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{
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unsigned int len;
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/* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
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if (!vq->vq_ops->get_buf(vq, &len))
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if (!vq->vq_ops->get_buf(vq, &data_avail))
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return;
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data_left += len;
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complete(&have_data);
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}
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static void register_buffer(void)
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/* The host will fill any buffer we give it with sweet, sweet randomness. */
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static void register_buffer(u8 *buf, size_t size)
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{
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struct scatterlist sg;
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sg_init_one(&sg, random_data+data_left, RANDOM_DATA_SIZE-data_left);
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sg_init_one(&sg, buf, size);
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/* There should always be room for one buffer. */
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if (vq->vq_ops->add_buf(vq, &sg, 0, 1, random_data) < 0)
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if (vq->vq_ops->add_buf(vq, &sg, 0, 1, buf) < 0)
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BUG();
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vq->vq_ops->kick(vq);
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}
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/* At least we don't udelay() in a loop like some other drivers. */
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static int virtio_data_present(struct hwrng *rng, int wait)
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static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
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{
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if (data_left >= sizeof(u32))
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return 1;
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again:
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if (!busy) {
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busy = true;
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init_completion(&have_data);
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register_buffer(buf, size);
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}
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if (!wait)
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return 0;
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wait_for_completion(&have_data);
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/* Not enough? Re-register. */
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if (unlikely(data_left < sizeof(u32))) {
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register_buffer();
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goto again;
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}
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busy = false;
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return 1;
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return data_avail;
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}
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/* virtio_data_present() must have succeeded before this is called. */
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static int virtio_data_read(struct hwrng *rng, u32 *data)
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static void virtio_cleanup(struct hwrng *rng)
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{
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BUG_ON(data_left < sizeof(u32));
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data_left -= sizeof(u32);
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*data = random_data[data_left / 4];
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if (data_left < sizeof(u32)) {
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init_completion(&have_data);
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register_buffer();
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}
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return sizeof(*data);
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if (busy)
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wait_for_completion(&have_data);
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}
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static struct hwrng virtio_hwrng = {
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.name = "virtio",
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.data_present = virtio_data_present,
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.data_read = virtio_data_read,
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.name = "virtio",
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.cleanup = virtio_cleanup,
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.read = virtio_read,
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};
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static int virtrng_probe(struct virtio_device *vdev)
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@ -112,7 +99,6 @@ static int virtrng_probe(struct virtio_device *vdev)
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return err;
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}
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register_buffer();
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return 0;
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}
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@ -138,21 +124,11 @@ static struct virtio_driver virtio_rng = {
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static int __init init(void)
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{
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int err;
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random_data = kmalloc(RANDOM_DATA_SIZE, GFP_KERNEL);
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if (!random_data)
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return -ENOMEM;
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err = register_virtio_driver(&virtio_rng);
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if (err)
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kfree(random_data);
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return err;
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return register_virtio_driver(&virtio_rng);
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}
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static void __exit fini(void)
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{
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kfree(random_data);
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unregister_virtio_driver(&virtio_rng);
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}
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module_init(init);
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