* [PATCH 2/2] virtio-rng: fixes for device registration/unregistration
2014-05-15 13:21 [PATCH 1/2] virtio-rng: fix boot with virtio-rng device Sasha Levin
@ 2014-05-15 13:21 ` Sasha Levin
2014-05-16 2:09 ` [PATCH 1/2] virtio-rng: fix boot with virtio-rng device Rusty Russell
1 sibling, 0 replies; 3+ messages in thread
From: Sasha Levin @ 2014-05-15 13:21 UTC (permalink / raw)
To: rusty; +Cc: mpm, herbert, linux-kernel, akong, Sasha Levin
There are several fixes in this patch (mostly because it's hard
splitting them up):
- Revert the name field in struct hwrng back to 'const'. Also, don't
do an extra kmalloc for the name - just wasteful.
- Deal with allocation failures properly.
- Use IDA to allocate device number instead of brute forcing one.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
drivers/char/hw_random/virtio-rng.c | 41 ++++++++++++++++++++---------------
include/linux/hw_random.h | 2 +-
2 files changed, 24 insertions(+), 19 deletions(-)
diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index 5b25daa..f3e7150 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -25,6 +25,7 @@
#include <linux/virtio_rng.h>
#include <linux/module.h>
+static DEFINE_IDA(rng_index_ida);
struct virtrng_info {
struct virtio_device *vdev;
@@ -33,6 +34,8 @@ struct virtrng_info {
unsigned int data_avail;
struct completion have_data;
bool busy;
+ char name[25];
+ int index;
};
static void random_recv_done(struct virtqueue *vq)
@@ -92,41 +95,45 @@ static void virtio_cleanup(struct hwrng *rng)
static int probe_common(struct virtio_device *vdev)
{
- int err, i;
+ int err, index;
struct virtrng_info *vi = NULL;
vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL);
- vi->hwrng.name = kmalloc(40, GFP_KERNEL);
+ if (!vi)
+ return -ENOMEM;
+
+ vi->index = index = ida_simple_get(&rng_index_ida, 0, 0, GFP_KERNEL);
+ if (index < 0) {
+ kfree(vi);
+ return index;
+ }
+ sprintf(vi->name, "virtio_rng.%d", index);
init_completion(&vi->have_data);
- vi->hwrng.read = virtio_read;
- vi->hwrng.cleanup = virtio_cleanup;
- vi->hwrng.priv = (unsigned long)vi;
+ vi->hwrng = (struct hwrng) {
+ .read = virtio_read,
+ .cleanup = virtio_cleanup,
+ .priv = (unsigned long)vi,
+ .name = vi->name,
+ };
vdev->priv = vi;
/* We expect a single virtqueue. */
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;
+ ida_simple_remove(&rng_index_ida, index);
return err;
}
- i = 0;
- do {
- sprintf(vi->hwrng.name, "virtio_rng.%d", i++);
- err = hwrng_register(&vi->hwrng);
- } while (err == -EEXIST);
-
+ err = hwrng_register(&vi->hwrng);
if (err) {
vdev->config->del_vqs(vdev);
- kfree(vi->hwrng.name);
vi->vq = NULL;
kfree(vi);
- vi = NULL;
+ ida_simple_remove(&rng_index_ida, index);
return err;
}
@@ -140,10 +147,8 @@ static void remove_common(struct virtio_device *vdev)
vi->busy = false;
hwrng_unregister(&vi->hwrng);
vdev->config->del_vqs(vdev);
- kfree(vi->hwrng.name);
- vi->vq = NULL;
+ ida_simple_remove(&rng_index_ida, vi->index);
kfree(vi);
- vi = NULL;
}
static int virtrng_probe(struct virtio_device *vdev)
diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h
index 02d9c87..b4b0eef 100644
--- a/include/linux/hw_random.h
+++ b/include/linux/hw_random.h
@@ -31,7 +31,7 @@
* @priv: Private data, for use by the RNG driver.
*/
struct hwrng {
- char *name;
+ const char *name;
int (*init)(struct hwrng *rng);
void (*cleanup)(struct hwrng *rng);
int (*data_present)(struct hwrng *rng, int wait);
--
1.7.10.4
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH 1/2] virtio-rng: fix boot with virtio-rng device
2014-05-15 13:21 [PATCH 1/2] virtio-rng: fix boot with virtio-rng device Sasha Levin
2014-05-15 13:21 ` [PATCH 2/2] virtio-rng: fixes for device registration/unregistration Sasha Levin
@ 2014-05-16 2:09 ` Rusty Russell
1 sibling, 0 replies; 3+ messages in thread
From: Rusty Russell @ 2014-05-16 2:09 UTC (permalink / raw)
To: Sasha Levin; +Cc: mpm, herbert, linux-kernel, akong, Sasha Levin
Sasha Levin <sasha.levin@oracle.com> writes:
> Commit "virtio-rng: support multiple virtio-rng devices" has broken
> boot with a virtio-rng device because the 'init' callback of the
> virtio-rng device was left unitialized to garbage, and got called
> by the hwrng infrastructure, killing the guest on boot.
>
> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> ---
>
> Also, do we really need multiple virtio-rng devices? I know it's
> nice to have, but if there isn't a solid use-case behind it we're
> just adding bugs to working code without any benefit.
Hmm, thanks for this. It's my fault, I should have gone through this
with a fine-tooth comb once I saw the const change in hwrng.
As Amos pointed out in the commit message, qemu support multiple entropy
sources. It's a line ball: since you've done the work, I'll apply it
(if you'd just submitted a bug report I'd probably revert the commit).
AFAICT Amos owes you a beer :)
Cheers,
Rusty.
PS: Added Fixes: line.
> drivers/char/hw_random/virtio-rng.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
> index 12e242b..5b25daa 100644
> --- a/drivers/char/hw_random/virtio-rng.c
> +++ b/drivers/char/hw_random/virtio-rng.c
> @@ -95,7 +95,7 @@ static int probe_common(struct virtio_device *vdev)
> int err, i;
> struct virtrng_info *vi = NULL;
>
> - vi = kmalloc(sizeof(struct virtrng_info), GFP_KERNEL);
> + vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL);
> vi->hwrng.name = kmalloc(40, GFP_KERNEL);
> init_completion(&vi->have_data);
>
> --
> 1.7.10.4
>
> --
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^ permalink raw reply [flat|nested] 3+ messages in thread