1 files changed, 445 insertions, 0 deletions
diff --git a/kernel/kfifo.c b/kernel/kfifo.c
new file mode 100644
index 00000000000..35edbe22e9a
--- /dev/null
+++ b/kernel/kfifo.c
@@ -0,0 +1,445 @@
+/*
+ * A generic kernel FIFO implementation.
+ *
+ * Copyright (C) 2009 Stefani Seibold <stefani@seibold.net>
+ * Copyright (C) 2004 Stelian Pop <stelian@popies.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/kfifo.h>
+#include <linux/log2.h>
+#include <linux/uaccess.h>
+
+static void _kfifo_init(struct kfifo *fifo, void *buffer,
+		unsigned int size)
+{
+	fifo->buffer = buffer;
+	fifo->size = size;
+
+	kfifo_reset(fifo);
+}
+
+/**
+ * kfifo_init - initialize a FIFO using a preallocated buffer
+ * @fifo: the fifo to assign the buffer
+ * @buffer: the preallocated buffer to be used.
+ * @size: the size of the internal buffer, this has to be a power of 2.
+ *
+ */
+void kfifo_init(struct kfifo *fifo, void *buffer, unsigned int size)
+{
+	/* size must be a power of 2 */
+	BUG_ON(!is_power_of_2(size));
+
+	_kfifo_init(fifo, buffer, size);
+}
+EXPORT_SYMBOL(kfifo_init);
+
+/**
+ * kfifo_alloc - allocates a new FIFO internal buffer
+ * @fifo: the fifo to assign then new buffer
+ * @size: the size of the buffer to be allocated, this have to be a power of 2.
+ * @gfp_mask: get_free_pages mask, passed to kmalloc()
+ *
+ * This function dynamically allocates a new fifo internal buffer
+ *
+ * The size will be rounded-up to a power of 2.
+ * The buffer will be release with kfifo_free().
+ * Return 0 if no error, otherwise the an error code
+ */
+int kfifo_alloc(struct kfifo *fifo, unsigned int size, gfp_t gfp_mask)
+{
+	unsigned char *buffer;
+
+	/*
+	 * round up to the next power of 2, since our 'let the indices
+	 * wrap' technique works only in this case.
+	 */
+	if (!is_power_of_2(size)) {
+		BUG_ON(size > 0x80000000);
+		size = roundup_pow_of_two(size);
+	}
+
+	buffer = kmalloc(size, gfp_mask);
+	if (!buffer) {
+		_kfifo_init(fifo, NULL, 0);
+		return -ENOMEM;
+	}
+
+	_kfifo_init(fifo, buffer, size);
+
+	return 0;
+}
+EXPORT_SYMBOL(kfifo_alloc);
+
+/**
+ * kfifo_free - frees the FIFO internal buffer
+ * @fifo: the fifo to be freed.
+ */
+void kfifo_free(struct kfifo *fifo)
+{
+	kfree(fifo->buffer);
+	_kfifo_init(fifo, NULL, 0);
+}
+EXPORT_SYMBOL(kfifo_free);
+
+/**
+ * kfifo_skip - skip output data
+ * @fifo: the fifo to be used.
+ * @len: number of bytes to skip
+ */
+void kfifo_skip(struct kfifo *fifo, unsigned int len)
+{
+	if (len < kfifo_len(fifo)) {
+		__kfifo_add_out(fifo, len);
+		return;
+	}
+	kfifo_reset_out(fifo);
+}
+EXPORT_SYMBOL(kfifo_skip);
+
+static inline void __kfifo_in_data(struct kfifo *fifo,
+		const void *from, unsigned int len, unsigned int off)
+{
+	unsigned int l;
+
+	/*
+	 * Ensure that we sample the fifo->out index -before- we
+	 * start putting bytes into the kfifo.
+	 */
+
+	smp_mb();
+
+	off = __kfifo_off(fifo, fifo->in + off);
+
+	/* first put the data starting from fifo->in to buffer end */
+	l = min(len, fifo->size - off);
+	memcpy(fifo->buffer + off, from, l);
+
+	/* then put the rest (if any) at the beginning of the buffer */
+	memcpy(fifo->buffer, from + l, len - l);
+}
+
+static inline void __kfifo_out_data(struct kfifo *fifo,
+		void *to, unsigned int len, unsigned int off)
+{
+	unsigned int l;
+
+	/*
+	 * 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);
+	memcpy(to, fifo->buffer + off, l);
+
+	/* then get the rest (if any) from the beginning of the buffer */
+	memcpy(to + l, fifo->buffer, len - l);
+}
+
+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;
+
+	/*
+	 * Ensure that we sample the fifo->out index -before- we
+	 * start putting bytes into the kfifo.
+	 */
+
+	smp_mb();
+
+	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)) {
+		*lenout = ret;
+		return -EFAULT;
+	}
+	*lenout = l;
+
+	/* then put the rest (if any) at the beginning of the buffer */
+	ret = copy_from_user(fifo->buffer, from + l, len - l);
+	*lenout += ret ? ret : len - l;
+	return ret ? -EFAULT : 0;
+}
+
+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;
+
+	/*
+	 * 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);
+	*lenout = l;
+	if (unlikely(ret)) {
+		*lenout -= ret;
+		return -EFAULT;
+	}
+
+	/* then get the rest (if any) from the beginning of the buffer */
+	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,
+	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 void *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_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_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, void *to, unsigned int len)
+{
+	len = min(kfifo_len(fifo), len);
+
+	__kfifo_out_data(fifo, to, len, 0);
+	__kfifo_add_out(fifo, len);
+
+	return len;
+}
+EXPORT_SYMBOL(kfifo_out);
+
+/**
+ * kfifo_out_peek - copy some data from the FIFO, but do not remove it
+ * @fifo: the fifo to be used.
+ * @to: where the data must be copied.
+ * @len: the size of the destination buffer.
+ * @offset: offset into the fifo
+ *
+ * This function copies at most @len bytes at @offset from the FIFO
+ * into the @to buffer and returns the number of copied bytes.
+ * The data is not removed from the FIFO.
+ */
+unsigned int kfifo_out_peek(struct kfifo *fifo, void *to, unsigned int len,
+			    unsigned offset)
+{
+	len = min(kfifo_len(fifo), len + offset);
+
+	__kfifo_out_data(fifo, to, len, offset);
+	return len;
+}
+EXPORT_SYMBOL(kfifo_out_peek);
+
+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);
+
+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;
+
+	__kfifo_from_user_data(fifo, from, len, recsize, &total);
+	return total;
+}
+EXPORT_SYMBOL(__kfifo_from_user_n);
+
+/**
+ * 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.
+ * @total: the actual returned data length.
+ *
+ * This function copies at most @len bytes from the @from into the
+ * 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.
+ */
+int kfifo_from_user(struct kfifo *fifo,
+        const void __user *from, unsigned int len, unsigned *total)
+{
+	int ret;
+	len = min(kfifo_avail(fifo), len);
+	ret = __kfifo_from_user_data(fifo, from, len, 0, total);
+	if (ret)
+		return ret;
+	__kfifo_add_in(fifo, len);
+	return 0;
+}
+EXPORT_SYMBOL(kfifo_from_user);
+
+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);
+
+unsigned int __kfifo_to_user_n(struct kfifo *fifo,
+	void __user *to, unsigned int len, unsigned int reclen,
+	unsigned int recsize)
+{
+	unsigned int ret, total;
+
+	if (kfifo_len(fifo) < reclen + recsize)
+		return len;
+
+	ret = __kfifo_to_user_data(fifo, to, reclen, recsize, &total);
+
+	if (likely(ret == 0))
+		__kfifo_add_out(fifo, reclen + recsize);
+
+	return total;
+}
+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.
+ * @lenout: pointer to output variable with copied data
+ *
+ * This function copies at most @len bytes from the FIFO into the
+ * @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.
+ */
+int kfifo_to_user(struct kfifo *fifo,
+	void __user *to, unsigned int len, unsigned *lenout)
+{
+	int ret;
+	len = min(kfifo_len(fifo), len);
+	ret = __kfifo_to_user_data(fifo, to, len, 0, lenout);
+	__kfifo_add_out(fifo, *lenout);
+	return ret;
+}
+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);
+