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hwrng: core - Replace u32 in driver API with byte array

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This patch implements a new method by which hw_random hardware drivers
can pass data to the core more efficiently, using a shared buffer.

The old methods have been retained as a compatability layer until all the
drivers have been updated.

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>
This commit is contained in:
Ian Molton 2009-12-01 14:47:32 +08:00 committed by Herbert Xu
parent 2f32bfd834
commit 9996508b33
2 changed files with 71 additions and 47 deletions
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101
drivers/char/hw_random/core.c
View file

@ -52,7 +52,8 @@
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] __cacheline_aligned;
static inline int hwrng_init(struct hwrng *rng)
{
@ -67,19 +68,6 @@ static inline void hwrng_cleanup(struct hwrng *rng)
rng->cleanup(rng);
}
static inline int hwrng_data_present(struct hwrng *rng, int wait)
{
if (!rng->data_present)
return 1;
return rng->data_present(rng, wait);
}
static inline int hwrng_data_read(struct hwrng *rng, u32 *data)
{
return rng->data_read(rng, data);
}
static int rng_dev_open(struct inode *inode, struct file *filp)
{
/* enforce read-only access to this chrdev */
@ -91,54 +79,87 @@ static int rng_dev_open(struct inode *inode, struct file *filp)
return 0;
}
static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
int wait) {
int present;
if (rng->read)
return rng->read(rng, (void *)buffer, size, wait);
if (rng->data_present)
present = rng->data_present(rng, wait);
else
present = 1;
if (present)
return rng->data_read(rng, (u32 *)buffer);
return 0;
}
static ssize_t rng_dev_read(struct file *filp, char __user *buf,
size_t size, loff_t *offp)
{
u32 data;
ssize_t ret = 0;
int err = 0;
int bytes_read;
int bytes_read, len;
while (size) {
if (mutex_lock_interruptible(&rng_mutex)) {
err = -ERESTARTSYS;
if (mutex_lock_interruptible(&rng_mutex))
goto out;
if (!current_rng) {
mutex_unlock(&rng_mutex);
err = -ENODEV;
goto out;
}
bytes_read = 0;
if (hwrng_data_present(current_rng,
!(filp->f_flags & O_NONBLOCK)))
bytes_read = hwrng_data_read(current_rng, &data);
mutex_unlock(&rng_mutex);
if (!current_rng) {
err = -ENODEV;
goto out_unlock;
}
err = -EAGAIN;
if (!bytes_read && (filp->f_flags & O_NONBLOCK))
goto out;
if (!data_avail) {
bytes_read = rng_get_data(current_rng, rng_buffer,
sizeof(rng_buffer),
!(filp->f_flags & O_NONBLOCK));
if (bytes_read < 0) {
err = bytes_read;
goto out;
goto out_unlock;
}
data_avail = bytes_read;
}
err = -EFAULT;
while (bytes_read && size) {
if (put_user((u8)data, buf++))
goto out;
size--;
ret++;
bytes_read--;
data >>= 8;
if (!data_avail) {
if (filp->f_flags & O_NONBLOCK) {
err = -EAGAIN;
goto out_unlock;
}
} else {
len = data_avail;
if (len > size)
len = size;
data_avail -= len;
if (copy_to_user(buf + ret, rng_buffer + data_avail,
len)) {
err = -EFAULT;
goto out_unlock;
}
size -= len;
ret += len;
}
mutex_unlock(&rng_mutex);
if (need_resched())
schedule_timeout_interruptible(1);
if (signal_pending(current)) {
err = -ERESTARTSYS;
if (signal_pending(current))
goto out;
}
}
out_unlock:
mutex_unlock(&rng_mutex);
out:
return ret ? : err;
}
@ -280,7 +301,7 @@ int hwrng_register(struct hwrng *rng)
struct hwrng *old_rng, *tmp;
if (rng->name == NULL ||
rng->data_read == NULL)
(rng->data_read == NULL && rng->read == NULL))
goto out;
mutex_lock(&rng_mutex);

7
include/linux/hw_random.h
View file

@ -22,10 +22,12 @@
* @cleanup: Cleanup callback (can be NULL).
* @data_present: Callback to determine if data is available
* on the RNG. If NULL, it is assumed that
* there is always data available.
* there is always data available. *OBSOLETE*
* @data_read: Read data from the RNG device.
* Returns the number of lower random bytes in "data".
* Must not be NULL.
* Must not be NULL. *OSOLETE*
* @read: New API. drivers can fill up to max bytes of data
* into the buffer. The buffer is aligned for any type.
* @priv: Private data, for use by the RNG driver.
*/
struct hwrng {
@ -34,6 +36,7 @@ struct hwrng {
void (*cleanup)(struct hwrng *rng);
int (*data_present)(struct hwrng *rng, int wait);
int (*data_read)(struct hwrng *rng, u32 *data);
int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);
unsigned long priv;
/* internal. */