1 files changed, 157 insertions, 0 deletions

diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
new file mode 100644
index 000000000000..c27cd428d269
--- /dev/null
+++ b/include/linux/kfifo.h
@@ -0,0 +1,157 @@
+/*
+ * A simple kernel FIFO implementation.
+ *
+ * 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.
+ *
+ */
+#ifndef _LINUX_KFIFO_H
+#define _LINUX_KFIFO_H
+
+#ifdef __KERNEL__
+
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+
+struct kfifo {
+        unsigned char *buffer;  /* the buffer holding the data */
+        unsigned int size;      /* the size of the allocated buffer */
+        unsigned int in;        /* data is added at offset (in % size) */
+        unsigned int out;       /* data is extracted from off. (out % size) */
+        spinlock_t *lock;       /* protects concurrent modifications */
+};
+
+extern struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size,
+                                unsigned int __nocast gfp_mask, spinlock_t *lock);
+extern struct kfifo *kfifo_alloc(unsigned int size, unsigned int __nocast gfp_mask,
+                                 spinlock_t *lock);
+extern void kfifo_free(struct kfifo *fifo);
+extern unsigned int __kfifo_put(struct kfifo *fifo,
+                                unsigned char *buffer, unsigned int len);
+extern unsigned int __kfifo_get(struct kfifo *fifo,
+                                unsigned char *buffer, unsigned int len);
+
+/**
+ * __kfifo_reset - removes the entire FIFO contents, no locking version
+ * @fifo: the fifo to be emptied.
+ */
+static inline void __kfifo_reset(struct kfifo *fifo)
+{
+        fifo->in = fifo->out = 0;
+}
+
+/**
+ * kfifo_reset - removes the entire FIFO contents
+ * @fifo: the fifo to be emptied.
+ */
+static inline void kfifo_reset(struct kfifo *fifo)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(fifo->lock, flags);
+
+        __kfifo_reset(fifo);
+
+        spin_unlock_irqrestore(fifo->lock, flags);
+}
+
+/**
+ * kfifo_put - puts some data into the FIFO
+ * @fifo: the fifo to be used.
+ * @buffer: the data to be added.
+ * @len: the length of the data to be added.
+ *
+ * This function copies at most 'len' bytes from the 'buffer' into
+ * the FIFO depending on the free space, and returns the number of
+ * bytes copied.
+ */
+static inline unsigned int kfifo_put(struct kfifo *fifo,
+                                     unsigned char *buffer, unsigned int len)
+{
+        unsigned long flags;
+        unsigned int ret;
+
+        spin_lock_irqsave(fifo->lock, flags);
+
+        ret = __kfifo_put(fifo, buffer, len);
+
+        spin_unlock_irqrestore(fifo->lock, flags);
+
+        return ret;
+}
+
+/**
+ * kfifo_get - gets some data from the FIFO
+ * @fifo: the fifo to be used.
+ * @buffer: 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
+ * 'buffer' and returns the number of copied bytes.
+ */
+static inline unsigned int kfifo_get(struct kfifo *fifo,
+                                     unsigned char *buffer, unsigned int len)
+{
+        unsigned long flags;
+        unsigned int ret;
+
+        spin_lock_irqsave(fifo->lock, flags);
+
+        ret = __kfifo_get(fifo, buffer, len);
+
+        /*
+         * optimization: if the FIFO is empty, set the indices to 0
+         * so we don't wrap the next time
+         */
+        if (fifo->in == fifo->out)
+                fifo->in = fifo->out = 0;
+
+        spin_unlock_irqrestore(fifo->lock, flags);
+
+        return ret;
+}
+
+/**
+ * __kfifo_len - returns the number of bytes available in the FIFO, no locking version
+ * @fifo: the fifo to be used.
+ */
+static inline unsigned int __kfifo_len(struct kfifo *fifo)
+{
+        return fifo->in - fifo->out;
+}
+
+/**
+ * kfifo_len - returns the number of bytes available in the FIFO
+ * @fifo: the fifo to be used.
+ */
+static inline unsigned int kfifo_len(struct kfifo *fifo)
+{
+        unsigned long flags;
+        unsigned int ret;
+
+        spin_lock_irqsave(fifo->lock, flags);
+
+        ret = __kfifo_len(fifo);
+
+        spin_unlock_irqrestore(fifo->lock, flags);
+
+        return ret;
+}
+
+#else
+#warning "don't include kernel headers in userspace"
+#endif /* __KERNEL__ */
+#endif