FreeBSD的buf_ring,该如何解决

FreeBSD的buf_ring
公司需要用到一个不加锁的队列实现线程同步，说是BSD上有，辛辛苦苦找来的.h .c源码，看不太懂，希望高手指教，小弟不胜感激。
buf_ring.h
32 #ifndef _SYS_BUF_RING_H_
33 #define _SYS_BUF_RING_H_
34
35 #include <machine/cpu.h>
36
37 #if defined(INVARIANTS) && !defined(DEBUG_BUFRING)
38 #define DEBUG_BUFRING 1
39 #endif
40
41 #ifdef DEBUG_BUFRING
42 #include <sys/lock.h>
43 #include <sys/mutex.h>
44 #endif
45
46 struct buf_ring {
47         volatile uint32_t       br_prod_head;
48         volatile uint32_t       br_prod_tail;   
49         int                     br_prod_size;
50         int                     br_prod_mask;
51         uint64_t                br_drops;
52         uint64_t                br_prod_bufs;
53         uint64_t                br_prod_bytes;
54         /*
55          * Pad out to next L2 cache line  
56          */
57         uint64_t                _pad0[11];
58
59         volatile uint32_t       br_cons_head;
60         volatile uint32_t       br_cons_tail;
61         int                     br_cons_size;
62         int                     br_cons_mask;
63         
64         /*
65          * Pad out to next L2 cache line
66          */
67         uint64_t                _pad1[14];
68 #ifdef DEBUG_BUFRING
69         struct mtx              *br_lock;
70 #endif  
71         void                    *br_ring[0];
72 };
7374 /*
75  * multi-producer safe lock-free ring buffer enqueue
76  *
77  */
78 static __inline int
79 buf_ring_enqueue_bytes(struct buf_ring *br, void *buf, int nbytes)
80 {
81         uint32_t prod_head, prod_next;
82         uint32_t cons_tail;
83         int success;
84 #ifdef DEBUG_BUFRING
85         int i;
86         for (i = br->br_cons_head; i != br->br_prod_head;
87              i = ((i + 1) & br->br_cons_mask))
88                 if(br->br_ring[i] == buf)
89                         panic("buf=%p already enqueue at %d prod=%d cons=%d",
90                             buf, i, br->br_prod_tail, br->br_cons_tail);
91 #endif  
92         critical_enter();
93         do {
94                 prod_head = br->br_prod_head;
95                 cons_tail = br->br_cons_tail;
96
97                 prod_next = (prod_head + 1) & br->br_prod_mask;
98