Move rtems/freebsd to freebsd and contrib to freebsd/contrib

1 files changed, 277 insertions, 0 deletions

diff --git a/freebsd/sys/buf_ring.h b/freebsd/sys/buf_ring.h
new file mode 100644
index 00000000..48b02f50
--- /dev/null
+++ b/freebsd/sys/buf_ring.h
@@ -0,0 +1,277 @@
+/*-
+ * Copyright (c) 2007-2009 Kip Macy <kmacy@freebsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ *
+ */
+
+#ifndef	_SYS_BUF_RING_HH_
+#define	_SYS_BUF_RING_HH_
+
+#include <rtems/freebsd/machine/cpu.h>
+
+#if defined(INVARIANTS) && !defined(DEBUG_BUFRING)
+#define DEBUG_BUFRING 1
+#endif
+
+#ifdef DEBUG_BUFRING
+#include <rtems/freebsd/sys/lock.h>
+#include <rtems/freebsd/sys/mutex.h>
+#endif
+
+struct buf_ring {
+	volatile uint32_t	br_prod_head;
+	volatile uint32_t	br_prod_tail;	
+	int              	br_prod_size;
+	int              	br_prod_mask;
+	uint64_t		br_drops;
+	uint64_t		br_prod_bufs;
+	uint64_t		br_prod_bytes;
+	/*
+	 * Pad out to next L2 cache line
+	 */
+	uint64_t	  	_pad0[11];
+
+	volatile uint32_t	br_cons_head;
+	volatile uint32_t	br_cons_tail;
+	int		 	br_cons_size;
+	int              	br_cons_mask;
+	
+	/*
+	 * Pad out to next L2 cache line
+	 */
+	uint64_t	  	_pad1[14];
+#ifdef DEBUG_BUFRING
+	struct mtx		*br_lock;
+#endif	
+	void			*br_ring[0];
+};
+
+/*
+ * multi-producer safe lock-free ring buffer enqueue
+ *
+ */
+static __inline int
+buf_ring_enqueue_bytes(struct buf_ring *br, void *buf, int nbytes)
+{
+	uint32_t prod_head, prod_next;
+	uint32_t cons_tail;
+	int success;
+#ifdef DEBUG_BUFRING
+	int i;
+	for (i = br->br_cons_head; i != br->br_prod_head;
+	     i = ((i + 1) & br->br_cons_mask))
+		if(br->br_ring[i] == buf)
+			panic("buf=%p already enqueue at %d prod=%d cons=%d",
+			    buf, i, br->br_prod_tail, br->br_cons_tail);
+#endif	
+	critical_enter();
+	do {
+		prod_head = br->br_prod_head;
+		cons_tail = br->br_cons_tail;
+
+		prod_next = (prod_head + 1) & br->br_prod_mask;
+		
+		if (prod_next == cons_tail) {
+			critical_exit();
+			return (ENOBUFS);
+		}
+		
+		success = atomic_cmpset_int(&br->br_prod_head, prod_head,
+		    prod_next);
+	} while (success == 0);
+#ifdef DEBUG_BUFRING
+	if (br->br_ring[prod_head] != NULL)
+		panic("dangling value in enqueue");
+#endif	
+	br->br_ring[prod_head] = buf;
+	wmb();
+
+	/*
+	 * If there are other enqueues in progress
+	 * that preceeded us, we need to wait for them
+	 * to complete 
+	 */   
+	while (br->br_prod_tail != prod_head)
+		cpu_spinwait();
+	br->br_prod_bufs++;
+	br->br_prod_bytes += nbytes;
+	br->br_prod_tail = prod_next;
+	critical_exit();
+	return (0);
+}
+
+static __inline int
+buf_ring_enqueue(struct buf_ring *br, void *buf)
+{
+
+	return (buf_ring_enqueue_bytes(br, buf, 0));
+}
+
+/*
+ * multi-consumer safe dequeue 
+ *
+ */
+static __inline void *
+buf_ring_dequeue_mc(struct buf_ring *br)
+{
+	uint32_t cons_head, cons_next;
+	uint32_t prod_tail;
+	void *buf;
+	int success;
+
+	critical_enter();
+	do {
+		cons_head = br->br_cons_head;
+		prod_tail = br->br_prod_tail;
+
+		cons_next = (cons_head + 1) & br->br_cons_mask;
+		
+		if (cons_head == prod_tail) {
+			critical_exit();
+			return (NULL);
+		}
+		
+		success = atomic_cmpset_int(&br->br_cons_head, cons_head,
+		    cons_next);
+	} while (success == 0);		
+
+	buf = br->br_ring[cons_head];
+#ifdef DEBUG_BUFRING
+	br->br_ring[cons_head] = NULL;
+#endif
+	rmb();
+	
+	/*
+	 * If there are other dequeues in progress
+	 * that preceeded us, we need to wait for them
+	 * to complete 
+	 */   
+	while (br->br_cons_tail != cons_head)
+		cpu_spinwait();
+
+	br->br_cons_tail = cons_next;
+	critical_exit();
+
+	return (buf);
+}
+
+/*
+ * single-consumer dequeue 
+ * use where dequeue is protected by a lock
+ * e.g. a network driver's tx queue lock
+ */
+static __inline void *
+buf_ring_dequeue_sc(struct buf_ring *br)
+{
+	uint32_t cons_head, cons_next, cons_next_next;
+	uint32_t prod_tail;
+	void *buf;
+	
+	cons_head = br->br_cons_head;
+	prod_tail = br->br_prod_tail;
+	
+	cons_next = (cons_head + 1) & br->br_cons_mask;
+	cons_next_next = (cons_head + 2) & br->br_cons_mask;
+	
+	if (cons_head == prod_tail) 
+		return (NULL);
+
+#ifdef PREFETCH_DEFINED	
+	if (cons_next != prod_tail) {		
+		prefetch(br->br_ring[cons_next]);
+		if (cons_next_next != prod_tail) 
+			prefetch(br->br_ring[cons_next_next]);
+	}
+#endif
+	br->br_cons_head = cons_next;
+	buf = br->br_ring[cons_head];
+
+#ifdef DEBUG_BUFRING
+	br->br_ring[cons_head] = NULL;
+	if (!mtx_owned(br->br_lock))
+		panic("lock not held on single consumer dequeue");
+	if (br->br_cons_tail != cons_head)
+		panic("inconsistent list cons_tail=%d cons_head=%d",
+		    br->br_cons_tail, cons_head);
+#endif
+	br->br_cons_tail = cons_next;
+	return (buf);
+}
+
+/*
+ * return a pointer to the first entry in the ring
+ * without modifying it, or NULL if the ring is empty
+ * race-prone if not protected by a lock
+ */
+static __inline void *
+buf_ring_peek(struct buf_ring *br)
+{
+
+#ifdef DEBUG_BUFRING
+	if ((br->br_lock != NULL) && !mtx_owned(br->br_lock))
+		panic("lock not held on single consumer dequeue");
+#endif	
+	/*
+	 * I believe it is safe to not have a memory barrier
+	 * here because we control cons and tail is worst case
+	 * a lagging indicator so we worst case we might
+	 * return NULL immediately after a buffer has been enqueued
+	 */
+	if (br->br_cons_head == br->br_prod_tail)
+		return (NULL);
+	
+	return (br->br_ring[br->br_cons_head]);
+}
+
+static __inline int
+buf_ring_full(struct buf_ring *br)
+{
+
+	return (((br->br_prod_head + 1) & br->br_prod_mask) == br->br_cons_tail);
+}
+
+static __inline int
+buf_ring_empty(struct buf_ring *br)
+{
+
+	return (br->br_cons_head == br->br_prod_tail);
+}
+
+static __inline int
+buf_ring_count(struct buf_ring *br)
+{
+
+	return ((br->br_prod_size + br->br_prod_tail - br->br_cons_tail)
+	    & br->br_prod_mask);
+}
+
+struct buf_ring *buf_ring_alloc(int count, struct malloc_type *type, int flags,
+    struct mtx *);
+void buf_ring_free(struct buf_ring *br, struct malloc_type *type);
+
+
+
+#endif