sys/sys/buf_ring.h

65 buf_ring_enqueue(struct buf_ring *br, void *buf)
70 	for (i = br->br_cons_head; i != br->br_prod_head;
71 	     i = ((i + 1) & br->br_cons_mask))
72 		if(br->br_ring[i] == buf)
74 			    buf, i, br->br_prod_tail, br->br_cons_tail);
78 		prod_head = br->br_prod_head;
79 		prod_next = (prod_head + 1) & br->br_prod_mask;
80 		cons_tail = br->br_cons_tail;
84 			if (prod_head == br->br_prod_head &&
85 			    cons_tail == br->br_cons_tail) {
86 				br->br_drops++;
92 	} while (!atomic_cmpset_acq_int(&br->br_prod_head, prod_head, prod_next));
94 	if (br->br_ring[prod_head] != NULL)
97 	br->br_ring[prod_head] = buf;
104 	while (br->br_prod_tail != prod_head)
106 	atomic_store_rel_int(&br->br_prod_tail, prod_next);
116 buf_ring_dequeue_mc(struct buf_ring *br)
123 		cons_head = br->br_cons_head;
124 		cons_next = (cons_head + 1) & br->br_cons_mask;
126 		if (cons_head == br->br_prod_tail) {
130 	} while (!atomic_cmpset_acq_int(&br->br_cons_head, cons_head, cons_next));
132 	buf = br->br_ring[cons_head];
134 	br->br_ring[cons_head] = NULL;
141 	while (br->br_cons_tail != cons_head)
144 	atomic_store_rel_int(&br->br_cons_tail, cons_next);
156 buf_ring_dequeue_sc(struct buf_ring *br)
178 	 *                                                                                cons_head = br->br_cons_head;
179 	 * atomic_cmpset_acq_32(&br->br_prod_head, ...));
180 	 *                                                                                buf = br->br_ring[cons_head];     <see <1>>
181 	 * br->br_ring[prod_head] = buf;
182 	 * atomic_store_rel_32(&br->br_prod_tail, ...);
183 	 *                                                                                prod_tail = br->br_prod_tail;
188 	 * <1> Load (on core 1) from br->br_ring[cons_head] can be reordered (speculative readed) by CPU.
191 	cons_head = atomic_load_acq_32(&br->br_cons_head);
193 	cons_head = br->br_cons_head;
195 	prod_tail = atomic_load_acq_32(&br->br_prod_tail);
197 	cons_next = (cons_head + 1) & br->br_cons_mask;
199 	cons_next_next = (cons_head + 2) & br->br_cons_mask;
207 		prefetch(br->br_ring[cons_next]);
209 			prefetch(br->br_ring[cons_next_next]);
212 	br->br_cons_head = cons_next;
213 	buf = br->br_ring[cons_head];
216 	br->br_ring[cons_head] = NULL;
217 	if (!mtx_owned(br->br_lock))
219 	if (br->br_cons_tail != cons_head)
221 		    br->br_cons_tail, cons_head);
223 	br->br_cons_tail = cons_next;
233 buf_ring_advance_sc(struct buf_ring *br)
238 	cons_head = br->br_cons_head;
239 	prod_tail = br->br_prod_tail;
241 	cons_next = (cons_head + 1) & br->br_cons_mask;
244 	br->br_cons_head = cons_next;
246 	br->br_ring[cons_head] = NULL;
248 	br->br_cons_tail = cons_next;
268 buf_ring_putback_sc(struct buf_ring *br, void *new)
270 	KASSERT(br->br_cons_head != br->br_prod_tail,
272 	br->br_ring[br->br_cons_head] = new;
281 buf_ring_peek(struct buf_ring *br)
285 	if ((br->br_lock != NULL) && !mtx_owned(br->br_lock))
294 	if (br->br_cons_head == br->br_prod_tail)
297 	return (br->br_ring[br->br_cons_head]);
301 buf_ring_peek_clear_sc(struct buf_ring *br)
306 	if (!mtx_owned(br->br_lock))
315 	if (br->br_cons_head == br->br_prod_tail)
323 	ret = br->br_ring[br->br_cons_head];
324 	br->br_ring[br->br_cons_head] = NULL;
327 	return (br->br_ring[br->br_cons_head]);
332 buf_ring_full(struct buf_ring *br)
335 	return (((br->br_prod_head + 1) & br->br_prod_mask) == br->br_cons_tail);
339 buf_ring_empty(struct buf_ring *br)
342 	return (br->br_cons_head == br->br_prod_tail);
346 buf_ring_count(struct buf_ring *br)
349 	return ((br->br_prod_size + br->br_prod_tail - br->br_cons_tail)
350 	    & br->br_prod_mask);
355 void buf_ring_free(struct buf_ring *br, struct malloc_type *type);