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Message-Id: <1259577501-17786-2-git-send-email-ian.molton@collabora.co.uk>
Date: Mon, 30 Nov 2009 10:38:20 +0000
From: Ian Molton <ian.molton@...labora.co.uk>
To: linux-kernel@...r.kernel.org
Cc: rusty@...tcorp.com.au, mpm@...enic.com, jeff@...zik.org,
herbert@...dor.apana.org.au,
Ian Molton <ian.molton@...labora.co.uk>
Subject: [PATCH 1/2] hw_random: core updates to allow more efficient drivers
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@...labora.co.uk>
---
drivers/char/hw_random/core.c | 107 ++++++++++++++++++++++++----------------
include/linux/hw_random.h | 7 ++-
2 files changed, 69 insertions(+), 45 deletions(-)
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 1573aeb..5c2d13c 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -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) {
- err = -ERESTARTSYS;
- if (mutex_lock_interruptible(&rng_mutex))
+ if (mutex_lock_interruptible(&rng_mutex)) {
+ err = -ERESTARTSYS;
goto out;
+ }
+
if (!current_rng) {
- mutex_unlock(&rng_mutex);
err = -ENODEV;
- goto out;
+ goto out_unlock;
}
- 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);
-
- err = -EAGAIN;
- if (!bytes_read && (filp->f_flags & O_NONBLOCK))
- goto out;
- if (bytes_read < 0) {
- err = bytes_read;
- 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_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);
- err = -ERESTARTSYS;
- if (signal_pending(current))
+
+ if (signal_pending(current)) {
+ err = -ERESTARTSYS;
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);
diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h
index 7244456..9bede76 100644
--- a/include/linux/hw_random.h
+++ b/include/linux/hw_random.h
@@ -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. */
--
1.6.5
--
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