compat/sys/buf_ring.h

67 buf_ring_enqueue(struct buf_ring *br, void *buf)
72 	for (i = br->br_cons_head; i != br->br_prod_head;
73 	     i = ((i + 1) & br->br_cons_mask))
74 		if(br->br_ring[i] == buf)
76 			    buf, i, br->br_prod_tail, br->br_cons_tail);
80 		prod_head = br->br_prod_head;
81 		prod_next = (prod_head + 1) & br->br_prod_mask;
82 		cons_tail = br->br_cons_tail;
86 			if (prod_head == br->br_prod_head &&
87 			    cons_tail == br->br_cons_tail) {
88 				br->br_drops++;
94 	} while (!atomic_cmpset_acq_int(&br->br_prod_head, prod_head, prod_next));
96 	if (br->br_ring[prod_head] != NULL)
99 	br->br_ring[prod_head] = buf;
106 	while (br->br_prod_tail != prod_head)
108 	atomic_store_rel_int(&br->br_prod_tail, prod_next);
118 buf_ring_dequeue_mc(struct buf_ring *br)
125 		cons_head = br->br_cons_head;
126 		cons_next = (cons_head + 1) & br->br_cons_mask;
128 		if (cons_head == br->br_prod_tail) {
132 	} while (!atomic_cmpset_acq_int(&br->br_cons_head, cons_head, cons_next));
134 	buf = br->br_ring[cons_head];
136 	br->br_ring[cons_head] = NULL;
143 	while (br->br_cons_tail != cons_head)
146 	atomic_store_rel_int(&br->br_cons_tail, cons_next);
158 buf_ring_dequeue_sc(struct buf_ring *br)
180 	 *                                                                                cons_head = br->br_cons_head;
181 	 * atomic_cmpset_acq_32(&br->br_prod_head, ...));
182 	 *                                                                                buf = br->br_ring[cons_head];     <see <1>>
183 	 * br->br_ring[prod_head] = buf;
184 	 * atomic_store_rel_32(&br->br_prod_tail, ...);
185 	 *                                                                                prod_tail = br->br_prod_tail;
190 	 * <1> Load (on core 1) from br->br_ring[cons_head] can be reordered (speculative readed) by CPU.
193 	cons_head = atomic_load_acq_32(&br->br_cons_head);
195 	cons_head = br->br_cons_head;
197 	prod_tail = atomic_load_acq_32(&br->br_prod_tail);
199 	cons_next = (cons_head + 1) & br->br_cons_mask;
201 	cons_next_next = (cons_head + 2) & br->br_cons_mask;
209 		prefetch(br->br_ring[cons_next]);
211 			prefetch(br->br_ring[cons_next_next]);
214 	br->br_cons_head = cons_next;
215 	buf = br->br_ring[cons_head];
218 	br->br_ring[cons_head] = NULL;
219 	if (!mtx_owned(br->br_lock))
221 	if (br->br_cons_tail != cons_head)
223 		    br->br_cons_tail, cons_head);
225 	br->br_cons_tail = cons_next;
235 buf_ring_advance_sc(struct buf_ring *br)
240 	cons_head = br->br_cons_head;
241 	prod_tail = br->br_prod_tail;
243 	cons_next = (cons_head + 1) & br->br_cons_mask;
246 	br->br_cons_head = cons_next;
248 	br->br_ring[cons_head] = NULL;
250 	br->br_cons_tail = cons_next;
270 buf_ring_putback_sc(struct buf_ring *br, void *_new)
272 	KASSERT_FREEBSD(br->br_cons_head != br->br_prod_tail,
274 	br->br_ring[br->br_cons_head] = _new;
283 buf_ring_peek(struct buf_ring *br)
287 	if ((br->br_lock != NULL) && !mtx_owned(br->br_lock))
296 	if (br->br_cons_head == br->br_prod_tail)
299 	return (br->br_ring[br->br_cons_head]);
303 buf_ring_peek_clear_sc(struct buf_ring *br)
308 	if (!mtx_owned(br->br_lock))
317 	if (br->br_cons_head == br->br_prod_tail)
325 	ret = br->br_ring[br->br_cons_head];
326 	br->br_ring[br->br_cons_head] = NULL;
329 	return (br->br_ring[br->br_cons_head]);
334 buf_ring_full(struct buf_ring *br)
337 	return (((br->br_prod_head + 1) & br->br_prod_mask) == br->br_cons_tail);
341 buf_ring_empty(struct buf_ring *br)
344 	return (br->br_cons_head == br->br_prod_tail);
348 buf_ring_count(struct buf_ring *br)
351 	return ((br->br_prod_size + br->br_prod_tail - br->br_cons_tail)
352 	    & br->br_prod_mask);
357 void buf_ring_free(struct buf_ring *br, struct malloc_type *type);