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Commit f7f154f1 authored by Rusty Russell's avatar Rusty Russell
Browse files

hw_random: make buffer usable in scatterlist. 



virtio_rng feeds the randomness buffer handed by the core directly
into the scatterlist, since commit bb347d98.

However, if CONFIG_HW_RANDOM=m, the static buffer isn't a linear address
(at least on most archs).  We could fix this in virtio_rng, but it's actually
far easier to just do it in the core as virtio_rng would have to allocate
a buffer every time (it doesn't know how much the core will want to read).

Reported-by: default avatarAurelien Jarno <aurelien@aurel32.net>
Tested-by: default avatarAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
parent 6dbe51c2

drivers/char/hw_random/core.c

+16 −3
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ 
#include <linux/init.h>

#include <linux/miscdevice.h>

#include <linux/delay.h>

#include <linux/slab.h>

#include <asm/uaccess.h>
@@ -52,8 +53,12 @@ static struct hwrng *current_rng; 
static LIST_HEAD(rng_list);

static DEFINE_MUTEX(rng_mutex);

static int data_avail;

static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES]

	__cacheline_aligned;

static u8 *rng_buffer;



static size_t rng_buffer_size(void)

{

	return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;

}



static inline int hwrng_init(struct hwrng *rng)

{
@@ -116,7 +121,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf, 


		if (!data_avail) {

			bytes_read = rng_get_data(current_rng, rng_buffer,

				sizeof(rng_buffer),

				rng_buffer_size(),

				!(filp->f_flags & O_NONBLOCK));

			if (bytes_read < 0) {

				err = bytes_read;
@@ -307,6 +312,14 @@ int hwrng_register(struct hwrng *rng) 


	mutex_lock(&rng_mutex);



	/* kmalloc makes this safe for virt_to_page() in virtio_rng.c */

	err = -ENOMEM;

	if (!rng_buffer) {

		rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);

		if (!rng_buffer)

			goto out_unlock;

	}



	/* Must not register two RNGs with the same name. */

	err = -EEXIST;

	list_for_each_entry(tmp, &rng_list, list) {