1 files changed, 607 insertions, 0 deletions

diff --git a/lib/kfifo.c b/lib/kfifo.c
new file mode 100644
index 000000000000..7b7f83027b7b
--- /dev/null
+++ b/lib/kfifo.c
@@ -0,0 +1,607 @@
+/*
+ * A generic kernel FIFO implementation
+ *
+ * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.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/export.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/log2.h>
+#include <linux/uaccess.h>
+#include <linux/kfifo.h>
+
+/*
+ * internal helper to calculate the unused elements in a fifo
+ */
+static inline unsigned int kfifo_unused(struct __kfifo *fifo)
+{
+        return (fifo->mask + 1) - (fifo->in - fifo->out);
+}
+
+int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
+                size_t esize, gfp_t gfp_mask)
+{
+        /*
+         * round down to the next power of 2, since our 'let the indices
+         * wrap' technique works only in this case.
+         */
+        size = roundup_pow_of_two(size);
+
+        fifo->in = 0;
+        fifo->out = 0;
+        fifo->esize = esize;
+
+        if (size < 2) {
+                fifo->data = NULL;
+                fifo->mask = 0;
+                return -EINVAL;
+        }
+
+        fifo->data = kmalloc(size * esize, gfp_mask);
+
+        if (!fifo->data) {
+                fifo->mask = 0;
+                return -ENOMEM;
+        }
+        fifo->mask = size - 1;
+
+        return 0;
+}
+EXPORT_SYMBOL(__kfifo_alloc);
+
+void __kfifo_free(struct __kfifo *fifo)
+{
+        kfree(fifo->data);
+        fifo->in = 0;
+        fifo->out = 0;
+        fifo->esize = 0;
+        fifo->data = NULL;
+        fifo->mask = 0;
+}
+EXPORT_SYMBOL(__kfifo_free);
+
+int __kfifo_init(struct __kfifo *fifo, void *buffer,
+                unsigned int size, size_t esize)
+{
+        size /= esize;
+
+        size = roundup_pow_of_two(size);
+
+        fifo->in = 0;
+        fifo->out = 0;
+        fifo->esize = esize;
+        fifo->data = buffer;
+
+        if (size < 2) {
+                fifo->mask = 0;
+                return -EINVAL;
+        }
+        fifo->mask = size - 1;
+
+        return 0;
+}
+EXPORT_SYMBOL(__kfifo_init);
+
+static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
+                unsigned int len, unsigned int off)
+{
+        unsigned int size = fifo->mask + 1;
+        unsigned int esize = fifo->esize;
+        unsigned int l;
+
+        off &= fifo->mask;
+        if (esize != 1) {
+                off *= esize;
+                size *= esize;
+                len *= esize;
+        }
+        l = min(len, size - off);
+
+        memcpy(fifo->data + off, src, l);
+        memcpy(fifo->data, src + l, len - l);
+        /*
+         * make sure that the data in the fifo is up to date before
+         * incrementing the fifo->in index counter
+         */
+        smp_wmb();
+}
+
+unsigned int __kfifo_in(struct __kfifo *fifo,
+                const void *buf, unsigned int len)
+{
+        unsigned int l;
+
+        l = kfifo_unused(fifo);
+        if (len > l)
+                len = l;
+
+        kfifo_copy_in(fifo, buf, len, fifo->in);
+        fifo->in += len;
+        return len;
+}
+EXPORT_SYMBOL(__kfifo_in);
+
+static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
+                unsigned int len, unsigned int off)
+{
+        unsigned int size = fifo->mask + 1;
+        unsigned int esize = fifo->esize;
+        unsigned int l;
+
+        off &= fifo->mask;
+        if (esize != 1) {
+                off *= esize;
+                size *= esize;
+                len *= esize;
+        }
+        l = min(len, size - off);
+
+        memcpy(dst, fifo->data + off, l);
+        memcpy(dst + l, fifo->data, len - l);
+        /*
+         * make sure that the data is copied before
+         * incrementing the fifo->out index counter
+         */
+        smp_wmb();
+}
+
+unsigned int __kfifo_out_peek(struct __kfifo *fifo,
+                void *buf, unsigned int len)
+{
+        unsigned int l;
+
+        l = fifo->in - fifo->out;
+        if (len > l)
+                len = l;
+
+        kfifo_copy_out(fifo, buf, len, fifo->out);
+        return len;
+}
+EXPORT_SYMBOL(__kfifo_out_peek);
+
+unsigned int __kfifo_out(struct __kfifo *fifo,
+                void *buf, unsigned int len)
+{
+        len = __kfifo_out_peek(fifo, buf, len);
+        fifo->out += len;
+        return len;
+}
+EXPORT_SYMBOL(__kfifo_out);
+
+static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
+        const void __user *from, unsigned int len, unsigned int off,
+        unsigned int *copied)
+{
+        unsigned int size = fifo->mask + 1;
+        unsigned int esize = fifo->esize;
+        unsigned int l;
+        unsigned long ret;
+
+        off &= fifo->mask;
+        if (esize != 1) {
+                off *= esize;
+                size *= esize;
+                len *= esize;
+        }
+        l = min(len, size - off);
+
+        ret = copy_from_user(fifo->data + off, from, l);
+        if (unlikely(ret))
+                ret = DIV_ROUND_UP(ret + len - l, esize);
+        else {
+                ret = copy_from_user(fifo->data, from + l, len - l);
+                if (unlikely(ret))
+                        ret = DIV_ROUND_UP(ret, esize);
+        }
+        /*
+         * make sure that the data in the fifo is up to date before
+         * incrementing the fifo->in index counter
+         */
+        smp_wmb();
+        *copied = len - ret;
+        /* return the number of elements which are not copied */
+        return ret;
+}
+
+int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
+                unsigned long len, unsigned int *copied)
+{
+        unsigned int l;
+        unsigned long ret;
+        unsigned int esize = fifo->esize;
+        int err;
+
+        if (esize != 1)
+                len /= esize;
+
+        l = kfifo_unused(fifo);
+        if (len > l)
+                len = l;
+
+        ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
+        if (unlikely(ret)) {
+                len -= ret;
+                err = -EFAULT;
+        } else
+                err = 0;
+        fifo->in += len;
+        return err;
+}
+EXPORT_SYMBOL(__kfifo_from_user);
+
+static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
+                unsigned int len, unsigned int off, unsigned int *copied)
+{
+        unsigned int l;
+        unsigned long ret;
+        unsigned int size = fifo->mask + 1;
+        unsigned int esize = fifo->esize;
+
+        off &= fifo->mask;
+        if (esize != 1) {
+                off *= esize;
+                size *= esize;
+                len *= esize;
+        }
+        l = min(len, size - off);
+
+        ret = copy_to_user(to, fifo->data + off, l);
+        if (unlikely(ret))
+                ret = DIV_ROUND_UP(ret + len - l, esize);
+        else {
+                ret = copy_to_user(to + l, fifo->data, len - l);
+                if (unlikely(ret))
+                        ret = DIV_ROUND_UP(ret, esize);
+        }
+        /*
+         * make sure that the data is copied before
+         * incrementing the fifo->out index counter
+         */
+        smp_wmb();
+        *copied = len - ret;
+        /* return the number of elements which are not copied */
+        return ret;
+}
+
+int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
+                unsigned long len, unsigned int *copied)
+{
+        unsigned int l;
+        unsigned long ret;
+        unsigned int esize = fifo->esize;
+        int err;
+
+        if (esize != 1)
+                len /= esize;
+
+        l = fifo->in - fifo->out;
+        if (len > l)
+                len = l;
+        ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
+        if (unlikely(ret)) {
+                len -= ret;
+                err = -EFAULT;
+        } else
+                err = 0;
+        fifo->out += len;
+        return err;
+}
+EXPORT_SYMBOL(__kfifo_to_user);
+
+static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
+                int nents, unsigned int len)
+{
+        int n;
+        unsigned int l;
+        unsigned int off;
+        struct page *page;
+
+        if (!nents)
+                return 0;
+
+        if (!len)
+                return 0;
+
+        n = 0;
+        page = virt_to_page(buf);
+        off = offset_in_page(buf);
+        l = 0;
+
+        while (len >= l + PAGE_SIZE - off) {
+                struct page *npage;
+
+                l += PAGE_SIZE;
+                buf += PAGE_SIZE;
+                npage = virt_to_page(buf);
+                if (page_to_phys(page) != page_to_phys(npage) - l) {
+                        sg_set_page(sgl, page, l - off, off);
+                        sgl = sg_next(sgl);
+                        if (++n == nents || sgl == NULL)
+                                return n;
+                        page = npage;
+                        len -= l - off;
+                        l = off = 0;
+                }
+        }
+        sg_set_page(sgl, page, len, off);
+        return n + 1;
+}
+
+static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
+                int nents, unsigned int len, unsigned int off)
+{
+        unsigned int size = fifo->mask + 1;
+        unsigned int esize = fifo->esize;
+        unsigned int l;
+        unsigned int n;
+
+        off &= fifo->mask;
+        if (esize != 1) {
+                off *= esize;
+                size *= esize;
+                len *= esize;
+        }
+        l = min(len, size - off);
+
+        n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
+        n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
+
+        return n;
+}
+
+unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
+                struct scatterlist *sgl, int nents, unsigned int len)
+{
+        unsigned int l;
+
+        l = kfifo_unused(fifo);
+        if (len > l)
+                len = l;
+
+        return setup_sgl(fifo, sgl, nents, len, fifo->in);
+}
+EXPORT_SYMBOL(__kfifo_dma_in_prepare);
+
+unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
+                struct scatterlist *sgl, int nents, unsigned int len)
+{
+        unsigned int l;
+
+        l = fifo->in - fifo->out;
+        if (len > l)
+                len = l;
+
+        return setup_sgl(fifo, sgl, nents, len, fifo->out);
+}
+EXPORT_SYMBOL(__kfifo_dma_out_prepare);
+
+unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
+{
+        unsigned int max = (1 << (recsize << 3)) - 1;
+
+        if (len > max)
+                return max;
+        return len;
+}
+EXPORT_SYMBOL(__kfifo_max_r);
+
+#define __KFIFO_PEEK(data, out, mask) \
+        ((data)[(out) & (mask)])
+/*
+ * __kfifo_peek_n internal helper function for determinate the length of
+ * the next record in the fifo
+ */
+static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
+{
+        unsigned int l;
+        unsigned int mask = fifo->mask;
+        unsigned char *data = fifo->data;
+
+        l = __KFIFO_PEEK(data, fifo->out, mask);
+
+        if (--recsize)
+                l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
+
+        return l;
+}
+
+#define __KFIFO_POKE(data, in, mask, val) \
+        ( \
+        (data)[(in) & (mask)] = (unsigned char)(val) \
+        )
+
+/*
+ * __kfifo_poke_n internal helper function for storeing the length of
+ * the record into the fifo
+ */
+static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
+{
+        unsigned int mask = fifo->mask;
+        unsigned char *data = fifo->data;
+
+        __KFIFO_POKE(data, fifo->in, mask, n);
+
+        if (recsize > 1)
+                __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
+}
+
+unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
+{
+        return __kfifo_peek_n(fifo, recsize);
+}
+EXPORT_SYMBOL(__kfifo_len_r);
+
+unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
+                unsigned int len, size_t recsize)
+{
+        if (len + recsize > kfifo_unused(fifo))
+                return 0;
+
+        __kfifo_poke_n(fifo, len, recsize);
+
+        kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
+        fifo->in += len + recsize;
+        return len;
+}
+EXPORT_SYMBOL(__kfifo_in_r);
+
+static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
+        void *buf, unsigned int len, size_t recsize, unsigned int *n)
+{
+        *n = __kfifo_peek_n(fifo, recsize);
+
+        if (len > *n)
+                len = *n;
+
+        kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
+        return len;
+}
+
+unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
+                unsigned int len, size_t recsize)
+{
+        unsigned int n;
+
+        if (fifo->in == fifo->out)
+                return 0;
+
+        return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
+}
+EXPORT_SYMBOL(__kfifo_out_peek_r);
+
+unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
+                unsigned int len, size_t recsize)
+{
+        unsigned int n;
+
+        if (fifo->in == fifo->out)
+                return 0;
+
+        len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
+        fifo->out += n + recsize;
+        return len;
+}
+EXPORT_SYMBOL(__kfifo_out_r);
+
+void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
+{
+        unsigned int n;
+
+        n = __kfifo_peek_n(fifo, recsize);
+        fifo->out += n + recsize;
+}
+EXPORT_SYMBOL(__kfifo_skip_r);
+
+int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
+        unsigned long len, unsigned int *copied, size_t recsize)
+{
+        unsigned long ret;
+
+        len = __kfifo_max_r(len, recsize);
+
+        if (len + recsize > kfifo_unused(fifo)) {
+                *copied = 0;
+                return 0;
+        }
+
+        __kfifo_poke_n(fifo, len, recsize);
+
+        ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
+        if (unlikely(ret)) {
+                *copied = 0;
+                return -EFAULT;
+        }
+        fifo->in += len + recsize;
+        return 0;
+}
+EXPORT_SYMBOL(__kfifo_from_user_r);
+
+int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
+        unsigned long len, unsigned int *copied, size_t recsize)
+{
+        unsigned long ret;
+        unsigned int n;
+
+        if (fifo->in == fifo->out) {
+                *copied = 0;
+                return 0;
+        }
+
+        n = __kfifo_peek_n(fifo, recsize);
+        if (len > n)
+                len = n;
+
+        ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
+        if (unlikely(ret)) {
+                *copied = 0;
+                return -EFAULT;
+        }
+        fifo->out += n + recsize;
+        return 0;
+}
+EXPORT_SYMBOL(__kfifo_to_user_r);
+
+unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
+        struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
+{
+        if (!nents)
+                BUG();
+
+        len = __kfifo_max_r(len, recsize);
+
+        if (len + recsize > kfifo_unused(fifo))
+                return 0;
+
+        return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
+}
+EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
+
+void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
+        unsigned int len, size_t recsize)
+{
+        len = __kfifo_max_r(len, recsize);
+        __kfifo_poke_n(fifo, len, recsize);
+        fifo->in += len + recsize;
+}
+EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
+
+unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
+        struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
+{
+        if (!nents)
+                BUG();
+
+        len = __kfifo_max_r(len, recsize);
+
+        if (len + recsize > fifo->in - fifo->out)
+                return 0;
+
+        return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
+}
+EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
+
+void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
+{
+        unsigned int len;
+
+        len = __kfifo_peek_n(fifo, recsize);
+        fifo->out += len + recsize;
+}
+EXPORT_SYMBOL(__kfifo_dma_out_finish_r);