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virtio-rng: support multiple virtio-rng devices

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Current hwrng core supports to register multiple hwrng devices,
and there is only one device really works in the same time.
QEMU alsu supports to have multiple virtio-rng backends.

This patch changes virtio-rng driver to support multiple
virtio-rng devices.

]# cat /sys/class/misc/hw_random/rng_available
virtio_rng.0 virtio_rng.1
]# cat /sys/class/misc/hw_random/rng_current
virtio_rng.0
]# echo -n virtio_rng.1 > /sys/class/misc/hw_random/rng_current
]# dd if=/dev/hwrng of=/dev/null

Signed-off-by: Amos Kong <akong@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Amos Kong 2014-05-14 10:33:46 +09:30 committed by Rusty Russell
parent e75279c4fb
commit 08e53fbdb8
2 changed files with 64 additions and 40 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

102
drivers/char/hw_random/virtio-rng.c
View file

@ -25,88 +25,108 @@
#include <linux/virtio_rng.h>
#include <linux/module.h>
static struct virtqueue *vq;
static unsigned int data_avail;
static DECLARE_COMPLETION(have_data);
static bool busy;
struct virtrng_info {
struct virtio_device *vdev;
struct hwrng hwrng;
struct virtqueue *vq;
unsigned int data_avail;
struct completion have_data;
bool busy;
};
static void random_recv_done(struct virtqueue *vq)
{
struct virtrng_info *vi = vq->vdev->priv;
/* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
if (!virtqueue_get_buf(vq, &data_avail))
if (!virtqueue_get_buf(vi->vq, &vi->data_avail))
return;
complete(&have_data);
complete(&vi->have_data);
}
/* The host will fill any buffer we give it with sweet, sweet randomness. */
static void register_buffer(u8 *buf, size_t size)
static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size)
{
struct scatterlist sg;
sg_init_one(&sg, buf, size);
/* There should always be room for one buffer. */
virtqueue_add_inbuf(vq, &sg, 1, buf, GFP_KERNEL);
virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL);
virtqueue_kick(vq);
virtqueue_kick(vi->vq);
}
static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
{
int ret;
struct virtrng_info *vi = (struct virtrng_info *)rng->priv;
if (!busy) {
busy = true;
init_completion(&have_data);
register_buffer(buf, size);
if (!vi->busy) {
vi->busy = true;
init_completion(&vi->have_data);
register_buffer(vi, buf, size);
}
if (!wait)
return 0;
ret = wait_for_completion_killable(&have_data);
ret = wait_for_completion_killable(&vi->have_data);
if (ret < 0)
return ret;
busy = false;
vi->busy = false;
return data_avail;
return vi->data_avail;
}
static void virtio_cleanup(struct hwrng *rng)
{
if (busy)
wait_for_completion(&have_data);
struct virtrng_info *vi = (struct virtrng_info *)rng->priv;
if (vi->busy)
wait_for_completion(&vi->have_data);
}
static struct hwrng virtio_hwrng = {
.name = "virtio",
.cleanup = virtio_cleanup,
.read = virtio_read,
};
static int probe_common(struct virtio_device *vdev)
{
int err;
int err, i;
struct virtrng_info *vi = NULL;
vi = kmalloc(sizeof(struct virtrng_info), GFP_KERNEL);
vi->hwrng.name = kmalloc(40, GFP_KERNEL);
init_completion(&vi->have_data);
vi->hwrng.read = virtio_read;
vi->hwrng.cleanup = virtio_cleanup;
vi->hwrng.priv = (unsigned long)vi;
vdev->priv = vi;
if (vq) {
/* We only support one device for now */
return -EBUSY;
}
/* We expect a single virtqueue. */
vq = virtio_find_single_vq(vdev, random_recv_done, "input");
if (IS_ERR(vq)) {
err = PTR_ERR(vq);
vq = NULL;
vi->vq = virtio_find_single_vq(vdev, random_recv_done, "input");
if (IS_ERR(vi->vq)) {
err = PTR_ERR(vi->vq);
kfree(vi->hwrng.name);
vi->vq = NULL;
kfree(vi);
vi = NULL;
return err;
}
err = hwrng_register(&virtio_hwrng);
i = 0;
do {
sprintf(vi->hwrng.name, "virtio_rng.%d", i++);
err = hwrng_register(&vi->hwrng);
} while (err == -EEXIST);
if (err) {
vdev->config->del_vqs(vdev);
vq = NULL;
kfree(vi->hwrng.name);
vi->vq = NULL;
kfree(vi);
vi = NULL;
return err;
}
@ -115,11 +135,15 @@ static int probe_common(struct virtio_device *vdev)
static void remove_common(struct virtio_device *vdev)
{
struct virtrng_info *vi = vdev->priv;
vdev->config->reset(vdev);
busy = false;
hwrng_unregister(&virtio_hwrng);
vi->busy = false;
hwrng_unregister(&vi->hwrng);
vdev->config->del_vqs(vdev);
vq = NULL;
kfree(vi->hwrng.name);
vi->vq = NULL;
kfree(vi);
vi = NULL;
}
static int virtrng_probe(struct virtio_device *vdev)

2
include/linux/hw_random.h
View file

@ -31,7 +31,7 @@
* @priv: Private data, for use by the RNG driver.
*/
struct hwrng {
const char *name;
char *name;
int (*init)(struct hwrng *rng);
void (*cleanup)(struct hwrng *rng);
int (*data_present)(struct hwrng *rng, int wait);