diff --git a/kernel/kfifo.c b/kernel/kfifo.c
index ab615e6..b50bb62 100644
--- a/kernel/kfifo.c
+++ b/kernel/kfifo.c
@@ -159,8 +159,9 @@
 	memcpy(to + l, fifo->buffer, len - l);
 }
 
-static inline unsigned int __kfifo_from_user_data(struct kfifo *fifo,
-	 const void __user *from, unsigned int len, unsigned int off)
+static inline int __kfifo_from_user_data(struct kfifo *fifo,
+	 const void __user *from, unsigned int len, unsigned int off,
+	 unsigned *lenout)
 {
 	unsigned int l;
 	int ret;
@@ -177,16 +178,20 @@
 	/* first put the data starting from fifo->in to buffer end */
 	l = min(len, fifo->size - off);
 	ret = copy_from_user(fifo->buffer + off, from, l);
-
-	if (unlikely(ret))
-		return ret + len - l;
+	if (unlikely(ret)) {
+		*lenout = ret;
+		return -EFAULT;
+	}
+	*lenout = l;
 
 	/* then put the rest (if any) at the beginning of the buffer */
-	return copy_from_user(fifo->buffer, from + l, len - l);
+	ret = copy_from_user(fifo->buffer, from + l, len - l);
+	*lenout += ret ? ret : len - l;
+	return ret ? -EFAULT : 0;
 }
 
-static inline unsigned int __kfifo_to_user_data(struct kfifo *fifo,
-		void __user *to, unsigned int len, unsigned int off)
+static inline int __kfifo_to_user_data(struct kfifo *fifo,
+		void __user *to, unsigned int len, unsigned int off, unsigned *lenout)
 {
 	unsigned int l;
 	int ret;
@@ -203,12 +208,21 @@
 	/* first get the data from fifo->out until the end of the buffer */
 	l = min(len, fifo->size - off);
 	ret = copy_to_user(to, fifo->buffer + off, l);
-
-	if (unlikely(ret))
-		return ret + len - l;
+	*lenout = l;
+	if (unlikely(ret)) {
+		*lenout -= ret;
+		return -EFAULT;
+	}
 
 	/* then get the rest (if any) from the beginning of the buffer */
-	return copy_to_user(to + l, fifo->buffer, len - l);
+	len -= l;
+	ret = copy_to_user(to + l, fifo->buffer, len);
+	if (unlikely(ret)) {
+		*lenout += len - ret;
+		return -EFAULT;
+	}
+	*lenout += len;
+	return 0;
 }
 
 unsigned int __kfifo_in_n(struct kfifo *fifo,
@@ -299,10 +313,13 @@
 unsigned int __kfifo_from_user_n(struct kfifo *fifo,
 	const void __user *from, unsigned int len, unsigned int recsize)
 {
+	unsigned total;
+
 	if (kfifo_avail(fifo) < len + recsize)
 		return len + 1;
 
-	return __kfifo_from_user_data(fifo, from, len, recsize);
+	__kfifo_from_user_data(fifo, from, len, recsize, &total);
+	return total;
 }
 EXPORT_SYMBOL(__kfifo_from_user_n);
 
@@ -313,18 +330,21 @@
  * @len: the length of the data to be added.
  *
  * This function copies at most @len bytes from the @from into the
- * FIFO depending and returns the number of copied bytes.
+ * FIFO depending and returns -EFAULT/0.
  *
  * Note that with only one concurrent reader and one concurrent
  * writer, you don't need extra locking to use these functions.
  */
-unsigned int kfifo_from_user(struct kfifo *fifo,
-	const void __user *from, unsigned int len)
+int kfifo_from_user(struct kfifo *fifo,
+        const void __user *from, unsigned int len, unsigned *total)
 {
+	int ret;
 	len = min(kfifo_avail(fifo), len);
-	len -= __kfifo_from_user_data(fifo, from, len, 0);
+	ret = __kfifo_from_user_data(fifo, from, len, 0, total);
+	if (ret)
+		return ret;
 	__kfifo_add_in(fifo, len);
-	return len;
+	return 0;
 }
 EXPORT_SYMBOL(kfifo_from_user);
 
@@ -339,17 +359,17 @@
 	void __user *to, unsigned int len, unsigned int reclen,
 	unsigned int recsize)
 {
-	unsigned int ret;
+	unsigned int ret, total;
 
 	if (kfifo_len(fifo) < reclen + recsize)
 		return len;
 
-	ret = __kfifo_to_user_data(fifo, to, reclen, recsize);
+	ret = __kfifo_to_user_data(fifo, to, reclen, recsize, &total);
 
 	if (likely(ret == 0))
 		__kfifo_add_out(fifo, reclen + recsize);
 
-	return ret;
+	return total;
 }
 EXPORT_SYMBOL(__kfifo_to_user_n);
 
@@ -358,20 +378,22 @@
  * @fifo: the fifo to be used.
  * @to: where the data must be copied.
  * @len: the size of the destination buffer.
+ @ @lenout: pointer to output variable with copied data
  *
  * This function copies at most @len bytes from the FIFO into the
- * @to buffer and returns the number of copied bytes.
+ * @to buffer and 0 or -EFAULT.
  *
  * Note that with only one concurrent reader and one concurrent
  * writer, you don't need extra locking to use these functions.
  */
-unsigned int kfifo_to_user(struct kfifo *fifo,
-	void __user *to, unsigned int len)
+int kfifo_to_user(struct kfifo *fifo,
+	void __user *to, unsigned int len, unsigned *lenout)
 {
+	int ret;
 	len = min(kfifo_len(fifo), len);
-	len -= __kfifo_to_user_data(fifo, to, len, 0);
-	__kfifo_add_out(fifo, len);
-	return len;
+	ret = __kfifo_to_user_data(fifo, to, len, 0, lenout);
+	__kfifo_add_out(fifo, *lenout);
+	return ret;
 }
 EXPORT_SYMBOL(kfifo_to_user);