virtio: handle short buffers in virtio_rng. (594de1dd) · Commits · 戴 / test

drivers/char/hw_random/virtio-rng.c

+16 −8

Original line number	Diff line number	Diff line
		@@ -35,13 +35,13 @@ static DECLARE_COMPLETION(have_data);

		static void random_recv_done(struct virtqueue *vq)
		{
		int len;
		unsigned int len;

		/* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
		if (!vq->vq_ops->get_buf(vq, &len))
		return;

		data_left = len / sizeof(random_data[0]);
		data_left += len;
		complete(&have_data);
		}

		@@ -49,7 +49,7 @@ static void register_buffer(void)
		{
		struct scatterlist sg;

		sg_init_one(&sg, random_data, RANDOM_DATA_SIZE);
		sg_init_one(&sg, random_data+data_left, RANDOM_DATA_SIZE-data_left);
		/* There should always be room for one buffer. */
		if (vq->vq_ops->add_buf(vq, &sg, 0, 1, random_data) != 0)
		BUG();
		@@ -59,24 +59,32 @@ static void register_buffer(void)
		/* At least we don't udelay() in a loop like some other drivers. */
		static int virtio_data_present(struct hwrng *rng, int wait)
		{
		if (data_left)
		if (data_left >= sizeof(u32))
		return 1;

		again:
		if (!wait)
		return 0;

		wait_for_completion(&have_data);

		/* Not enough? Re-register. */
		if (unlikely(data_left < sizeof(u32))) {
		register_buffer();
		goto again;
		}

		return 1;
		}

		/* virtio_data_present() must have succeeded before this is called. */
		static int virtio_data_read(struct hwrng rng, u32 data)
		{
		BUG_ON(!data_left);

		*data = random_data[--data_left];
		BUG_ON(data_left < sizeof(u32));
		data_left -= sizeof(u32);
		*data = random_data[data_left / 4];

		if (!data_left) {
		if (data_left < sizeof(u32)) {
		init_completion(&have_data);
		register_buffer();
		}