Signed-off-by: Michael Buesch <mb@bu3sch.de>
Index: hwrng.fixes/drivers/char/hw_random/core.c
===================================================================
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 drivers/char/hw_random/core.c |   53 ++++++++++++++------------------
 1 files changed, 24 insertions(+), 29 deletions(-)

diff -puN drivers/char/hw_random/core.c~add-new-generic-hw-rng-core-hw_random-core-rewrite-chrdev-read-method drivers/char/hw_random/core.c
--- devel/drivers/char/hw_random/core.c~add-new-generic-hw-rng-core-hw_random-core-rewrite-chrdev-read-method	2006-05-18 00:46:19.000000000 -0700
+++ devel-akpm/drivers/char/hw_random/core.c	2006-05-18 00:46:19.000000000 -0700
@@ -91,10 +91,11 @@ static int rng_dev_open(struct inode *in
 static ssize_t rng_dev_read(struct file *filp, char __user *buf,
 			    size_t size, loff_t *offp)
 {
-	int have_data;
 	u32 data;
 	ssize_t ret = 0;
 	int i, err = 0;
+	int data_present;
+	int bytes_read;
 
 	while (size) {
 		err = -ERESTARTSYS;
@@ -105,44 +106,38 @@ static ssize_t rng_dev_read(struct file 
 			err = -ENODEV;
 			goto out;
 		}
-		have_data = 0;
-		if (hwrng_data_present(current_rng))
-			have_data = hwrng_data_read(current_rng, &data);
+		if (filp->f_flags & O_NONBLOCK) {
+			data_present = hwrng_data_present(current_rng);
+		} else {
+			/* Some RNG require some time between data_reads to gather
+			 * new entropy. Poll it.
+			 */
+			for (i = 0; i < 20; i++) {
+				data_present = hwrng_data_present(current_rng);
+				if (data_present)
+					break;
+				udelay(10);
+			}
+		}
+		bytes_read = 0;
+		if (data_present)
+			bytes_read = hwrng_data_read(current_rng, &data);
 		mutex_unlock(&rng_mutex);
 
+		err = -EAGAIN;
+		if (!bytes_read)
+			goto out;
+
 		err = -EFAULT;
-		while (have_data && size) {
+		while (bytes_read && size) {
 			if (put_user((u8)data, buf++))
 				goto out;
 			size--;
 			ret++;
-			have_data--;
+			bytes_read--;
 			data >>= 8;
 		}
 
-		err = -EAGAIN;
-		if (filp->f_flags & O_NONBLOCK)
-			goto out;
-
-		err = -ERESTARTSYS;
-		if (need_resched()) {
-			if (schedule_timeout_interruptible(1))
-				goto out;
-		} else {
-			if (mutex_lock_interruptible(&rng_mutex))
-				goto out;
-			if (!current_rng) {
-				mutex_unlock(&rng_mutex);
-				err = -ENODEV;
-				goto out;
-			}
-			for (i = 0; i < 20; i++) {
-				if (hwrng_data_present(current_rng))
-					break;
-				udelay(10);
-			}
-			mutex_unlock(&rng_mutex);
-		}
 		if (signal_pending(current))
 			goto out;
 	}
_