kfifo: add record handling functions

Add kfifo_in_rec() - puts some record data into the FIFO
 Add kfifo_out_rec() - gets some record data from the FIFO
 Add kfifo_from_user_rec() - puts some data from user space into the FIFO
 Add kfifo_to_user_rec() - gets data from the FIFO and write it to user space
 Add kfifo_peek_rec() - gets the size of the next FIFO record field
 Add kfifo_skip_rec() - skip the next fifo out record
 Add kfifo_avail_rec() - determinate the number of bytes available in a record FIFO

Signed-off-by: Stefani Seibold <stefani@seibold.net>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 523 insertions, 93 deletions

diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
index d3230fb08bc7..486e8ad3bb50 100644
--- a/include/linux/kfifo.h
+++ b/include/linux/kfifo.h
@@ -278,4 +278,334 @@ static inline unsigned int __kfifo_off(struct kfifo *fifo, unsigned int off)
         return off & (fifo->size - 1);
 }
 
+/**
+ * __kfifo_peek_n internal helper function for determinate the length of
+ * the next record in the fifo
+ */
+static inline unsigned int __kfifo_peek_n(struct kfifo *fifo,
+                                unsigned int recsize)
+{
+#define __KFIFO_GET(fifo, off, shift) \
+        ((fifo)->buffer[__kfifo_off((fifo), (fifo)->out+(off))] << (shift))
+
+        unsigned int l;
+
+        l = __KFIFO_GET(fifo, 0, 0);
+
+        if (--recsize)
+                l |= __KFIFO_GET(fifo, 1, 8);
+
+        return l;
+#undef  __KFIFO_GET
+}
+
+/**
+ * __kfifo_poke_n internal helper function for storing the length of
+ * the next record into the fifo
+ */
+static inline void __kfifo_poke_n(struct kfifo *fifo,
+                        unsigned int recsize, unsigned int n)
+{
+#define __KFIFO_PUT(fifo, off, val, shift) \
+                ( \
+                (fifo)->buffer[__kfifo_off((fifo), (fifo)->in+(off))] = \
+                (unsigned char)((val) >> (shift)) \
+                )
+
+        __KFIFO_PUT(fifo, 0, n, 0);
+
+        if (--recsize)
+                __KFIFO_PUT(fifo, 1, n, 8);
+#undef  __KFIFO_PUT
+}
+
+/**
+ * __kfifo_in_... internal functions for put date into the fifo
+ * do not call it directly, use kfifo_in_rec() instead
+ */
+extern unsigned int __kfifo_in_n(struct kfifo *fifo,
+        const void *from, unsigned int n, unsigned int recsize);
+
+extern unsigned int __kfifo_in_generic(struct kfifo *fifo,
+        const void *from, unsigned int n, unsigned int recsize);
+
+static inline unsigned int __kfifo_in_rec(struct kfifo *fifo,
+        const void *from, unsigned int n, unsigned int recsize)
+{
+        unsigned int ret;
+
+        ret = __kfifo_in_n(fifo, from, n, recsize);
+
+        if (likely(ret == 0)) {
+                if (recsize)
+                        __kfifo_poke_n(fifo, recsize, n);
+                __kfifo_add_in(fifo, n + recsize);
+        }
+        return ret;
+}
+
+/**
+ * kfifo_in_rec - puts some record data into the FIFO
+ * @fifo: the fifo to be used.
+ * @from: the data to be added.
+ * @n: the length of the data to be added.
+ * @recsize: size of record field
+ *
+ * This function copies @n bytes from the @from into the FIFO and returns
+ * the number of bytes which cannot be copied.
+ * A returned value greater than the @n value means that the record doesn't
+ * fit into the buffer.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these functions.
+ */
+static inline __must_check unsigned int kfifo_in_rec(struct kfifo *fifo,
+        void *from, unsigned int n, unsigned int recsize)
+{
+        if (!__builtin_constant_p(recsize))
+                return __kfifo_in_generic(fifo, from, n, recsize);
+        return __kfifo_in_rec(fifo, from, n, recsize);
+}
+
+/**
+ * __kfifo_out_... internal functions for get date from the fifo
+ * do not call it directly, use kfifo_out_rec() instead
+ */
+extern unsigned int __kfifo_out_n(struct kfifo *fifo,
+        void *to, unsigned int reclen, unsigned int recsize);
+
+extern unsigned int __kfifo_out_generic(struct kfifo *fifo,
+        void *to, unsigned int n,
+        unsigned int recsize, unsigned int *total);
+
+static inline unsigned int __kfifo_out_rec(struct kfifo *fifo,
+        void *to, unsigned int n, unsigned int recsize,
+        unsigned int *total)
+{
+        unsigned int l;
+
+        if (!recsize) {
+                l = n;
+                if (total)
+                        *total = l;
+        } else {
+                l = __kfifo_peek_n(fifo, recsize);
+                if (total)
+                        *total = l;
+                if (n < l)
+                        return l;
+        }
+
+        return __kfifo_out_n(fifo, to, l, recsize);
+}
+
+/**
+ * kfifo_out_rec - gets some record data from the FIFO
+ * @fifo: the fifo to be used.
+ * @to: where the data must be copied.
+ * @n: the size of the destination buffer.
+ * @recsize: size of record field
+ * @total: pointer where the total number of to copied bytes should stored
+ *
+ * This function copies at most @n bytes from the FIFO to @to and returns the
+ * number of bytes which cannot be copied.
+ * A returned value greater than the @n value means that the record doesn't
+ * fit into the @to buffer.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these functions.
+ */
+static inline __must_check unsigned int kfifo_out_rec(struct kfifo *fifo,
+        void *to, unsigned int n, unsigned int recsize,
+        unsigned int *total)
+
+{
+        if (!__builtin_constant_p(recsize))
+                return __kfifo_out_generic(fifo, to, n, recsize, total);
+        return __kfifo_out_rec(fifo, to, n, recsize, total);
+}
+
+/**
+ * __kfifo_from_user_... internal functions for transfer from user space into
+ * the fifo. do not call it directly, use kfifo_from_user_rec() instead
+ */
+extern unsigned int __kfifo_from_user_n(struct kfifo *fifo,
+        const void __user *from, unsigned int n, unsigned int recsize);
+
+extern unsigned int __kfifo_from_user_generic(struct kfifo *fifo,
+        const void __user *from, unsigned int n, unsigned int recsize);
+
+static inline unsigned int __kfifo_from_user_rec(struct kfifo *fifo,
+        const void __user *from, unsigned int n, unsigned int recsize)
+{
+        unsigned int ret;
+
+        ret = __kfifo_from_user_n(fifo, from, n, recsize);
+
+        if (likely(ret == 0)) {
+                if (recsize)
+                        __kfifo_poke_n(fifo, recsize, n);
+                __kfifo_add_in(fifo, n + recsize);
+        }
+        return ret;
+}
+
+/**
+ * kfifo_from_user_rec - puts some data from user space into the FIFO
+ * @fifo: the fifo to be used.
+ * @from: pointer to the data to be added.
+ * @n: the length of the data to be added.
+ * @recsize: size of record field
+ *
+ * This function copies @n bytes from the @from into the
+ * FIFO and returns the number of bytes which cannot be copied.
+ *
+ * If the returned value is equal or less the @n value, the copy_from_user()
+ * functions has failed. Otherwise the record doesn't fit into the buffer.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these functions.
+ */
+static inline __must_check unsigned int kfifo_from_user_rec(struct kfifo *fifo,
+        const void __user *from, unsigned int n, unsigned int recsize)
+{
+        if (!__builtin_constant_p(recsize))
+                return __kfifo_from_user_generic(fifo, from, n, recsize);
+        return __kfifo_from_user_rec(fifo, from, n, recsize);
+}
+
+/**
+ * __kfifo_to_user_... internal functions for transfer fifo data into user space
+ * do not call it directly, use kfifo_to_user_rec() instead
+ */
+extern unsigned int __kfifo_to_user_n(struct kfifo *fifo,
+        void __user *to, unsigned int n, unsigned int reclen,
+        unsigned int recsize);
+
+extern unsigned int __kfifo_to_user_generic(struct kfifo *fifo,
+        void __user *to, unsigned int n, unsigned int recsize,
+        unsigned int *total);
+
+static inline unsigned int __kfifo_to_user_rec(struct kfifo *fifo,
+        void __user *to, unsigned int n,
+        unsigned int recsize, unsigned int *total)
+{
+        unsigned int l;
+
+        if (!recsize) {
+                l = n;
+                if (total)
+                        *total = l;
+        } else {
+                l = __kfifo_peek_n(fifo, recsize);
+                if (total)
+                        *total = l;
+                if (n < l)
+                        return l;
+        }
+
+        return __kfifo_to_user_n(fifo, to, n, l, recsize);
+}
+
+/**
+ * kfifo_to_user_rec - gets data from the FIFO and write it to user space
+ * @fifo: the fifo to be used.
+ * @to: where the data must be copied.
+ * @n: the size of the destination buffer.
+ * @recsize: size of record field
+ * @total: pointer where the total number of to copied bytes should stored
+ *
+ * This function copies at most @n bytes from the FIFO to the @to.
+ * In case of an error, the function returns the number of bytes which cannot
+ * be copied.
+ * If the returned value is equal or less the @n value, the copy_to_user()
+ * functions has failed. Otherwise the record doesn't fit into the @to buffer.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these functions.
+ */
+static inline __must_check unsigned int kfifo_to_user_rec(struct kfifo *fifo,
+                void __user *to, unsigned int n, unsigned int recsize,
+                unsigned int *total)
+{
+        if (!__builtin_constant_p(recsize))
+                return __kfifo_to_user_generic(fifo, to, n, recsize, total);
+        return __kfifo_to_user_rec(fifo, to, n, recsize, total);
+}
+
+/**
+ * __kfifo_peek_... internal functions for peek into the next fifo record
+ * do not call it directly, use kfifo_peek_rec() instead
+ */
+extern unsigned int __kfifo_peek_generic(struct kfifo *fifo,
+                                unsigned int recsize);
+
+/**
+ * kfifo_peek_rec - gets the size of the next FIFO record data
+ * @fifo: the fifo to be used.
+ * @recsize: size of record field
+ *
+ * This function returns the size of the next FIFO record in number of bytes
+ */
+static inline __must_check unsigned int kfifo_peek_rec(struct kfifo *fifo,
+        unsigned int recsize)
+{
+        if (!__builtin_constant_p(recsize))
+                return __kfifo_peek_generic(fifo, recsize);
+        if (!recsize)
+                return kfifo_len(fifo);
+        return __kfifo_peek_n(fifo, recsize);
+}
+
+/**
+ * __kfifo_skip_... internal functions for skip the next fifo record
+ * do not call it directly, use kfifo_skip_rec() instead
+ */
+extern void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize);
+
+static inline void __kfifo_skip_rec(struct kfifo *fifo,
+        unsigned int recsize)
+{
+        unsigned int l;
+
+        if (recsize) {
+                l = __kfifo_peek_n(fifo, recsize);
+
+                if (l + recsize <= kfifo_len(fifo)) {
+                        __kfifo_add_out(fifo, l + recsize);
+                        return;
+                }
+        }
+        kfifo_reset_out(fifo);
+}
+
+/**
+ * kfifo_skip_rec - skip the next fifo out record
+ * @fifo: the fifo to be used.
+ * @recsize: size of record field
+ *
+ * This function skips the next FIFO record
+ */
+static inline void kfifo_skip_rec(struct kfifo *fifo,
+        unsigned int recsize)
+{
+        if (!__builtin_constant_p(recsize))
+                __kfifo_skip_generic(fifo, recsize);
+        else
+                __kfifo_skip_rec(fifo, recsize);
+}
+
+/**
+ * kfifo_avail_rec - returns the number of bytes available in a record FIFO
+ * @fifo: the fifo to be used.
+ * @recsize: size of record field
+ */
+static inline __must_check unsigned int kfifo_avail_rec(struct kfifo *fifo,
+        unsigned int recsize)
+{
+        unsigned int l = kfifo_size(fifo) - kfifo_len(fifo);
+
+        return (l > recsize) ? l - recsize : 0;
+}
+
 #endif
diff --git a/kernel/kfifo.c b/kernel/kfifo.c
index 2a78425ef67f..e92d519f93b1 100644
--- a/kernel/kfifo.c
+++ b/kernel/kfifo.c
@@ -115,27 +115,11 @@ void kfifo_skip(struct kfifo *fifo, unsigned int len)
 }
 EXPORT_SYMBOL(kfifo_skip);
 
-/**
- * kfifo_in - puts some data into the FIFO
- * @fifo: the fifo to be used.
- * @from: the data to be added.
- * @len: the length of the data to be added.
- *
- * This function copies at most @len bytes from the @from buffer into
- * the FIFO depending on the free space, and returns the number of
- * bytes copied.
- *
- * Note that with only one concurrent reader and one concurrent
- * writer, you don't need extra locking to use these functions.
- */
-unsigned int kfifo_in(struct kfifo *fifo,
-                        const unsigned char *from, unsigned int len)
+static inline void __kfifo_in_data(struct kfifo *fifo,
+                const void *from, unsigned int len, unsigned int off)
 {
-        unsigned int off;
         unsigned int l;
 
-        len = min(len, fifo->size - fifo->in + fifo->out);
-
         /*
          * Ensure that we sample the fifo->out index -before- we
          * start putting bytes into the kfifo.
@@ -143,7 +127,7 @@ unsigned int kfifo_in(struct kfifo *fifo,
 
         smp_mb();
 
-        off = __kfifo_off(fifo, fifo->in);
+        off = __kfifo_off(fifo, fifo->in + off);
 
         /* first put the data starting from fifo->in to buffer end */
         l = min(len, fifo->size - off);
@@ -151,33 +135,13 @@ unsigned int kfifo_in(struct kfifo *fifo,
 
         /* then put the rest (if any) at the beginning of the buffer */
         memcpy(fifo->buffer, from + l, len - l);
-
-        __kfifo_add_in(fifo, len);
-
-        return len;
 }
-EXPORT_SYMBOL(kfifo_in);
 
-/**
- * kfifo_out - gets some data from the FIFO
- * @fifo: the fifo to be used.
- * @to: where the data must be copied.
- * @len: the size of the destination buffer.
- *
- * This function copies at most @len bytes from the FIFO into the
- * @to buffer and returns the number of copied bytes.
- *
- * Note that with only one concurrent reader and one concurrent
- * writer, you don't need extra locking to use these functions.
- */
-unsigned int kfifo_out(struct kfifo *fifo,
-                         unsigned char *to, unsigned int len)
+static inline void __kfifo_out_data(struct kfifo *fifo,
+                void *to, unsigned int len, unsigned int off)
 {
-        unsigned int off;
         unsigned int l;
 
-        len = min(len, fifo->in - fifo->out);
-
         /*
          * Ensure that we sample the fifo->in index -before- we
          * start removing bytes from the kfifo.
@@ -185,7 +149,7 @@ unsigned int kfifo_out(struct kfifo *fifo,
 
         smp_rmb();
 
-        off = __kfifo_off(fifo, fifo->out);
+        off = __kfifo_off(fifo, fifo->out + off);
 
         /* first get the data from fifo->out until the end of the buffer */
         l = min(len, fifo->size - off);
@@ -193,34 +157,14 @@ unsigned int kfifo_out(struct kfifo *fifo,
 
         /* then get the rest (if any) from the beginning of the buffer */
         memcpy(to + l, fifo->buffer, len - l);
-
-        __kfifo_add_out(fifo, len);
-
-        return len;
 }
-EXPORT_SYMBOL(kfifo_out);
 
-/**
- * kfifo_from_user - puts some data from user space into the FIFO
- * @fifo: the fifo to be used.
- * @from: pointer to the data to be added.
- * @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.
- *
- * 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)
+static inline unsigned int __kfifo_from_user_data(struct kfifo *fifo,
+         const void __user *from, unsigned int len, unsigned int off)
 {
-        unsigned int off;
         unsigned int l;
         int ret;
 
-        len = min(len, fifo->size - fifo->in + fifo->out);
-
         /*
          * Ensure that we sample the fifo->out index -before- we
          * start putting bytes into the kfifo.
@@ -228,29 +172,101 @@ unsigned int kfifo_from_user(struct kfifo *fifo,
 
         smp_mb();
 
-        off = __kfifo_off(fifo, fifo->in);
+        off = __kfifo_off(fifo, fifo->in + off);
 
         /* 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 l - ret;
+                return ret + len - l;
 
         /* then put the rest (if any) at the beginning of the buffer */
-        ret = copy_from_user(fifo->buffer, from + l, len - l);
+        return copy_from_user(fifo->buffer, from + l, len - l);
+}
+
+static inline unsigned int __kfifo_to_user_data(struct kfifo *fifo,
+                void __user *to, unsigned int len, unsigned int off)
+{
+        unsigned int l;
+        int ret;
+
+        /*
+         * Ensure that we sample the fifo->in index -before- we
+         * start removing bytes from the kfifo.
+         */
+
+        smp_rmb();
+
+        off = __kfifo_off(fifo, fifo->out + off);
+
+        /* 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 len - ret;
+                return ret + len - l;
 
-        __kfifo_add_in(fifo, len);
+        /* then get the rest (if any) from the beginning of the buffer */
+        return copy_to_user(to + l, fifo->buffer, len - l);
+}
 
+unsigned int __kfifo_in_n(struct kfifo *fifo,
+        const void *from, unsigned int len, unsigned int recsize)
+{
+        if (kfifo_avail(fifo) < len + recsize)
+                return len + 1;
+
+        __kfifo_in_data(fifo, from, len, recsize);
+        return 0;
+}
+EXPORT_SYMBOL(__kfifo_in_n);
+
+/**
+ * kfifo_in - puts some data into the FIFO
+ * @fifo: the fifo to be used.
+ * @from: the data to be added.
+ * @len: the length of the data to be added.
+ *
+ * This function copies at most @len bytes from the @from buffer into
+ * the FIFO depending on the free space, and returns the number of
+ * bytes copied.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these functions.
+ */
+unsigned int kfifo_in(struct kfifo *fifo, const unsigned char *from,
+                                unsigned int len)
+{
+        len = min(kfifo_avail(fifo), len);
+
+        __kfifo_in_data(fifo, from, len, 0);
+        __kfifo_add_in(fifo, len);
         return len;
 }
-EXPORT_SYMBOL(kfifo_from_user);
+EXPORT_SYMBOL(kfifo_in);
+
+unsigned int __kfifo_in_generic(struct kfifo *fifo,
+        const void *from, unsigned int len, unsigned int recsize)
+{
+        return __kfifo_in_rec(fifo, from, len, recsize);
+}
+EXPORT_SYMBOL(__kfifo_in_generic);
+
+unsigned int __kfifo_out_n(struct kfifo *fifo,
+        void *to, unsigned int len, unsigned int recsize)
+{
+        if (kfifo_len(fifo) < len + recsize)
+                return len;
+
+        __kfifo_out_data(fifo, to, len, recsize);
+        __kfifo_add_out(fifo, len + recsize);
+        return 0;
+}
+EXPORT_SYMBOL(__kfifo_out_n);
 
 /**
- * kfifo_to_user - gets data from the FIFO and write it to user space
+ * kfifo_out - gets some data from the FIFO
  * @fifo: the fifo to be used.
  * @to: where the data must be copied.
  * @len: the size of the destination buffer.
@@ -261,40 +277,124 @@ EXPORT_SYMBOL(kfifo_from_user);
  * 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)
+unsigned int kfifo_out(struct kfifo *fifo, unsigned char *to, unsigned int len)
 {
-        unsigned int off;
-        unsigned int l;
-        int ret;
+        len = min(kfifo_len(fifo), len);
 
-        len = min(len, fifo->in - fifo->out);
+        __kfifo_out_data(fifo, to, len, 0);
+        __kfifo_add_out(fifo, len);
 
-        /*
-         * Ensure that we sample the fifo->in index -before- we
-         * start removing bytes from the kfifo.
-         */
+        return len;
+}
+EXPORT_SYMBOL(kfifo_out);
 
-        smp_rmb();
+unsigned int __kfifo_out_generic(struct kfifo *fifo,
+        void *to, unsigned int len, unsigned int recsize,
+        unsigned int *total)
+{
+        return __kfifo_out_rec(fifo, to, len, recsize, total);
+}
+EXPORT_SYMBOL(__kfifo_out_generic);
 
-        off = __kfifo_off(fifo, fifo->out);
+unsigned int __kfifo_from_user_n(struct kfifo *fifo,
+        const void __user *from, unsigned int len, unsigned int recsize)
+{
+        if (kfifo_avail(fifo) < len + recsize)
+                return len + 1;
 
-        /* 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);
+        return __kfifo_from_user_data(fifo, from, len, recsize);
+}
+EXPORT_SYMBOL(__kfifo_from_user_n);
 
-        if (unlikely(ret))
-                return l - ret;
+/**
+ * kfifo_from_user - puts some data from user space into the FIFO
+ * @fifo: the fifo to be used.
+ * @from: pointer to the data to be added.
+ * @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.
+ *
+ * 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)
+{
+        len = min(kfifo_avail(fifo), len);
+        len -= __kfifo_from_user_data(fifo, from, len, 0);
+        __kfifo_add_in(fifo, len);
+        return len;
+}
+EXPORT_SYMBOL(kfifo_from_user);
 
-        /* then get the rest (if any) from the beginning of the buffer */
-        ret = copy_to_user(to + l, fifo->buffer, len - l);
+unsigned int __kfifo_from_user_generic(struct kfifo *fifo,
+        const void __user *from, unsigned int len, unsigned int recsize)
+{
+        return __kfifo_from_user_rec(fifo, from, len, recsize);
+}
+EXPORT_SYMBOL(__kfifo_from_user_generic);
 
-        if (unlikely(ret))
-                return len - ret;
+unsigned int __kfifo_to_user_n(struct kfifo *fifo,
+        void __user *to, unsigned int len, unsigned int reclen,
+        unsigned int recsize)
+{
+        unsigned int ret;
 
-        __kfifo_add_out(fifo, len);
+        if (kfifo_len(fifo) < reclen + recsize)
+                return len;
 
+        ret = __kfifo_to_user_data(fifo, to, reclen, recsize);
+
+        if (likely(ret == 0))
+                __kfifo_add_out(fifo, reclen + recsize);
+
+        return ret;
+}
+EXPORT_SYMBOL(__kfifo_to_user_n);
+
+/**
+ * kfifo_to_user - gets data from the FIFO and write it to user space
+ * @fifo: the fifo to be used.
+ * @to: where the data must be copied.
+ * @len: the size of the destination buffer.
+ *
+ * This function copies at most @len bytes from the FIFO into the
+ * @to buffer and returns the number of copied bytes.
+ *
+ * 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)
+{
+        len = min(kfifo_len(fifo), len);
+        len -= __kfifo_to_user_data(fifo, to, len, 0);
+        __kfifo_add_out(fifo, len);
         return len;
 }
 EXPORT_SYMBOL(kfifo_to_user);
 
+unsigned int __kfifo_to_user_generic(struct kfifo *fifo,
+        void __user *to, unsigned int len, unsigned int recsize,
+        unsigned int *total)
+{
+        return __kfifo_to_user_rec(fifo, to, len, recsize, total);
+}
+EXPORT_SYMBOL(__kfifo_to_user_generic);
+
+unsigned int __kfifo_peek_generic(struct kfifo *fifo, unsigned int recsize)
+{
+        if (recsize == 0)
+                return kfifo_avail(fifo);
+
+        return __kfifo_peek_n(fifo, recsize);
+}
+EXPORT_SYMBOL(__kfifo_peek_generic);
+
+void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize)
+{
+        __kfifo_skip_rec(fifo, recsize);
+}
+EXPORT_SYMBOL(__kfifo_skip_generic);
+