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>

1 files changed, 330 insertions, 0 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