1c0dd49bdSEiji Ota /*
2*16e76cddSagiri  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
3c0dd49bdSEiji Ota  */
4*16e76cddSagiri 
5c0dd49bdSEiji Ota /*
6*16e76cddSagiri  * This file contains code imported from the OFED rds source file ib_ring.c
7*16e76cddSagiri  * Oracle elects to have and use the contents of ib_ring.c under and governed
8*16e76cddSagiri  * by the OpenIB.org BSD license (see below for full license text). However,
9*16e76cddSagiri  * the following notice accompanied the original version of this file:
10c0dd49bdSEiji Ota  */
11c0dd49bdSEiji Ota 
12c0dd49bdSEiji Ota /*
13c0dd49bdSEiji Ota  * Copyright (c) 2006 Oracle.  All rights reserved.
14c0dd49bdSEiji Ota  *
15c0dd49bdSEiji Ota  * This software is available to you under a choice of one of two
16c0dd49bdSEiji Ota  * licenses.  You may choose to be licensed under the terms of the GNU
17c0dd49bdSEiji Ota  * General Public License (GPL) Version 2, available from the file
18c0dd49bdSEiji Ota  * COPYING in the main directory of this source tree, or the
19c0dd49bdSEiji Ota  * OpenIB.org BSD license below:
20c0dd49bdSEiji Ota  *
21c0dd49bdSEiji Ota  *     Redistribution and use in source and binary forms, with or
22c0dd49bdSEiji Ota  *     without modification, are permitted provided that the following
23c0dd49bdSEiji Ota  *     conditions are met:
24c0dd49bdSEiji Ota  *
25c0dd49bdSEiji Ota  *      - Redistributions of source code must retain the above
26c0dd49bdSEiji Ota  *        copyright notice, this list of conditions and the following
27c0dd49bdSEiji Ota  *        disclaimer.
28c0dd49bdSEiji Ota  *
29c0dd49bdSEiji Ota  *      - Redistributions in binary form must reproduce the above
30c0dd49bdSEiji Ota  *        copyright notice, this list of conditions and the following
31c0dd49bdSEiji Ota  *        disclaimer in the documentation and/or other materials
32c0dd49bdSEiji Ota  *        provided with the distribution.
33c0dd49bdSEiji Ota  *
34c0dd49bdSEiji Ota  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
35c0dd49bdSEiji Ota  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
36c0dd49bdSEiji Ota  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
37c0dd49bdSEiji Ota  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
38c0dd49bdSEiji Ota  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
39c0dd49bdSEiji Ota  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
40c0dd49bdSEiji Ota  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
41c0dd49bdSEiji Ota  * SOFTWARE.
42c0dd49bdSEiji Ota  *
43c0dd49bdSEiji Ota  */
44c0dd49bdSEiji Ota #include <sys/rds.h>
45c0dd49bdSEiji Ota 
46c0dd49bdSEiji Ota #include <sys/ib/clients/rdsv3/rdsv3.h>
47c0dd49bdSEiji Ota #include <sys/ib/clients/rdsv3/ib.h>
48c0dd49bdSEiji Ota #include <sys/ib/clients/rdsv3/rdsv3_debug.h>
49c0dd49bdSEiji Ota 
50c0dd49bdSEiji Ota /*
51c0dd49bdSEiji Ota  * Locking for IB rings.
52c0dd49bdSEiji Ota  * We assume that allocation is always protected by a mutex
53c0dd49bdSEiji Ota  * in the caller (this is a valid assumption for the current
54c0dd49bdSEiji Ota  * implementation).
55c0dd49bdSEiji Ota  *
56c0dd49bdSEiji Ota  * Freeing always happens in an interrupt, and hence only
57c0dd49bdSEiji Ota  * races with allocations, but not with other free()s.
58c0dd49bdSEiji Ota  *
59c0dd49bdSEiji Ota  * The interaction between allocation and freeing is that
60c0dd49bdSEiji Ota  * the alloc code has to determine the number of free entries.
61c0dd49bdSEiji Ota  * To this end, we maintain two counters; an allocation counter
62c0dd49bdSEiji Ota  * and a free counter. Both are allowed to run freely, and wrap
63c0dd49bdSEiji Ota  * around.
64c0dd49bdSEiji Ota  * The number of used entries is always (alloc_ctr - free_ctr) % NR.
65c0dd49bdSEiji Ota  *
66c0dd49bdSEiji Ota  * The current implementation makes free_ctr atomic. When the
67c0dd49bdSEiji Ota  * caller finds an allocation fails, it should set an "alloc fail"
68c0dd49bdSEiji Ota  * bit and retry the allocation. The "alloc fail" bit essentially tells
69c0dd49bdSEiji Ota  * the CQ completion handlers to wake it up after freeing some
70c0dd49bdSEiji Ota  * more entries.
71c0dd49bdSEiji Ota  */
72c0dd49bdSEiji Ota 
73c0dd49bdSEiji Ota void
rdsv3_ib_ring_init(struct rdsv3_ib_work_ring * ring,uint32_t nr)74c0dd49bdSEiji Ota rdsv3_ib_ring_init(struct rdsv3_ib_work_ring *ring, uint32_t nr)
75c0dd49bdSEiji Ota {
76c0dd49bdSEiji Ota 	(void) memset(ring, 0, sizeof (*ring));
77c0dd49bdSEiji Ota 	ring->w_nr = nr;
78c0dd49bdSEiji Ota 	RDSV3_DPRINTF5("rdsv3_ib_ring_init", "ring %p nr %u", ring, ring->w_nr);
79c0dd49bdSEiji Ota }
80c0dd49bdSEiji Ota 
81c0dd49bdSEiji Ota static inline uint32_t
__rdsv3_ib_ring_used(struct rdsv3_ib_work_ring * ring)82c0dd49bdSEiji Ota __rdsv3_ib_ring_used(struct rdsv3_ib_work_ring *ring)
83c0dd49bdSEiji Ota {
84c0dd49bdSEiji Ota 	uint32_t diff;
85c0dd49bdSEiji Ota 
86c0dd49bdSEiji Ota 	/* This assumes that atomic_t has at least as many bits as uint32_t */
87c0dd49bdSEiji Ota 	diff = ring->w_alloc_ctr - (uint32_t)atomic_get(&ring->w_free_ctr);
88c0dd49bdSEiji Ota 	ASSERT(diff <= ring->w_nr);
89c0dd49bdSEiji Ota 
90c0dd49bdSEiji Ota 	return (diff);
91c0dd49bdSEiji Ota }
92c0dd49bdSEiji Ota 
93c0dd49bdSEiji Ota void
rdsv3_ib_ring_resize(struct rdsv3_ib_work_ring * ring,uint32_t nr)94c0dd49bdSEiji Ota rdsv3_ib_ring_resize(struct rdsv3_ib_work_ring *ring, uint32_t nr)
95c0dd49bdSEiji Ota {
96c0dd49bdSEiji Ota 	/*
97c0dd49bdSEiji Ota 	 * We only ever get called from the connection setup code,
98c0dd49bdSEiji Ota 	 * prior to creating the QP.
99c0dd49bdSEiji Ota 	 */
100c0dd49bdSEiji Ota 	ASSERT(!__rdsv3_ib_ring_used(ring));
101c0dd49bdSEiji Ota 	ring->w_nr = nr;
102c0dd49bdSEiji Ota }
103c0dd49bdSEiji Ota 
104c0dd49bdSEiji Ota static int
__rdsv3_ib_ring_empty(struct rdsv3_ib_work_ring * ring)105c0dd49bdSEiji Ota __rdsv3_ib_ring_empty(struct rdsv3_ib_work_ring *ring)
106c0dd49bdSEiji Ota {
107c0dd49bdSEiji Ota 	return (__rdsv3_ib_ring_used(ring) == 0);
108c0dd49bdSEiji Ota }
109c0dd49bdSEiji Ota 
110c0dd49bdSEiji Ota uint32_t
rdsv3_ib_ring_alloc(struct rdsv3_ib_work_ring * ring,uint32_t val,uint32_t * pos)111c0dd49bdSEiji Ota rdsv3_ib_ring_alloc(struct rdsv3_ib_work_ring *ring, uint32_t val,
112c0dd49bdSEiji Ota     uint32_t *pos)
113c0dd49bdSEiji Ota {
114c0dd49bdSEiji Ota 	uint32_t ret = 0, avail;
115c0dd49bdSEiji Ota 
116c0dd49bdSEiji Ota 	avail = ring->w_nr - __rdsv3_ib_ring_used(ring);
117c0dd49bdSEiji Ota 
118c0dd49bdSEiji Ota 	RDSV3_DPRINTF5("rdsv3_ib_ring_alloc",
119c0dd49bdSEiji Ota 	    "ring %p val %u next %u free %u", ring, val,
120c0dd49bdSEiji Ota 	    ring->w_alloc_ptr, avail);
121c0dd49bdSEiji Ota 
122c0dd49bdSEiji Ota 	if (val && avail) {
123c0dd49bdSEiji Ota 		ret = min(val, avail);
124c0dd49bdSEiji Ota 		*pos = ring->w_alloc_ptr;
125c0dd49bdSEiji Ota 
126c0dd49bdSEiji Ota 		ring->w_alloc_ptr = (ring->w_alloc_ptr + ret) % ring->w_nr;
127c0dd49bdSEiji Ota 		ring->w_alloc_ctr += ret;
128c0dd49bdSEiji Ota 	}
129c0dd49bdSEiji Ota 
130c0dd49bdSEiji Ota 	return (ret);
131c0dd49bdSEiji Ota }
132c0dd49bdSEiji Ota 
133c0dd49bdSEiji Ota void
rdsv3_ib_ring_free(struct rdsv3_ib_work_ring * ring,uint32_t val)134c0dd49bdSEiji Ota rdsv3_ib_ring_free(struct rdsv3_ib_work_ring *ring, uint32_t val)
135c0dd49bdSEiji Ota {
136c0dd49bdSEiji Ota 	ring->w_free_ptr = (ring->w_free_ptr + val) % ring->w_nr;
137c0dd49bdSEiji Ota 	atomic_add_32(&ring->w_free_ctr, val);
138c0dd49bdSEiji Ota 
139c0dd49bdSEiji Ota 	if (__rdsv3_ib_ring_empty(ring))
1405d5562f5SEiji Ota 		rdsv3_wake_up(&ring->w_empty_wait);
141c0dd49bdSEiji Ota }
142c0dd49bdSEiji Ota 
143c0dd49bdSEiji Ota void
rdsv3_ib_ring_unalloc(struct rdsv3_ib_work_ring * ring,uint32_t val)144c0dd49bdSEiji Ota rdsv3_ib_ring_unalloc(struct rdsv3_ib_work_ring *ring, uint32_t val)
145c0dd49bdSEiji Ota {
146c0dd49bdSEiji Ota 	ring->w_alloc_ptr = (ring->w_alloc_ptr - val) % ring->w_nr;
147c0dd49bdSEiji Ota 	ring->w_alloc_ctr -= val;
148c0dd49bdSEiji Ota }
149c0dd49bdSEiji Ota 
150c0dd49bdSEiji Ota int
rdsv3_ib_ring_empty(struct rdsv3_ib_work_ring * ring)151c0dd49bdSEiji Ota rdsv3_ib_ring_empty(struct rdsv3_ib_work_ring *ring)
152c0dd49bdSEiji Ota {
153c0dd49bdSEiji Ota 	return (__rdsv3_ib_ring_empty(ring));
154c0dd49bdSEiji Ota }
155c0dd49bdSEiji Ota 
156c0dd49bdSEiji Ota int
rdsv3_ib_ring_low(struct rdsv3_ib_work_ring * ring)157c0dd49bdSEiji Ota rdsv3_ib_ring_low(struct rdsv3_ib_work_ring *ring)
158c0dd49bdSEiji Ota {
159cadbfdc3SEiji Ota 	return (__rdsv3_ib_ring_used(ring) <= (ring->w_nr >> 2));
160c0dd49bdSEiji Ota }
161c0dd49bdSEiji Ota 
162c0dd49bdSEiji Ota /*
163c0dd49bdSEiji Ota  * returns the oldest alloced ring entry.  This will be the next one
164c0dd49bdSEiji Ota  * freed.  This can't be called if there are none allocated.
165c0dd49bdSEiji Ota  */
166c0dd49bdSEiji Ota uint32_t
rdsv3_ib_ring_oldest(struct rdsv3_ib_work_ring * ring)167c0dd49bdSEiji Ota rdsv3_ib_ring_oldest(struct rdsv3_ib_work_ring *ring)
168c0dd49bdSEiji Ota {
169c0dd49bdSEiji Ota 	return (ring->w_free_ptr);
170c0dd49bdSEiji Ota }
171c0dd49bdSEiji Ota 
172c0dd49bdSEiji Ota /*
173c0dd49bdSEiji Ota  * returns the number of completed work requests.
174c0dd49bdSEiji Ota  */
175c0dd49bdSEiji Ota 
176c0dd49bdSEiji Ota uint32_t
rdsv3_ib_ring_completed(struct rdsv3_ib_work_ring * ring,uint32_t wr_id,uint32_t oldest)177c0dd49bdSEiji Ota rdsv3_ib_ring_completed(struct rdsv3_ib_work_ring *ring,
178c0dd49bdSEiji Ota     uint32_t wr_id, uint32_t oldest)
179c0dd49bdSEiji Ota {
180c0dd49bdSEiji Ota 	uint32_t ret;
181c0dd49bdSEiji Ota 
182c0dd49bdSEiji Ota 	if (oldest <= (unsigned long long)wr_id)
183c0dd49bdSEiji Ota 		ret = (unsigned long long)wr_id - oldest + 1;
184c0dd49bdSEiji Ota 	else
185c0dd49bdSEiji Ota 		ret = ring->w_nr - oldest + (unsigned long long)wr_id + 1;
186c0dd49bdSEiji Ota 
187c0dd49bdSEiji Ota 	RDSV3_DPRINTF5("rdsv3_ib_ring_completed",
188c0dd49bdSEiji Ota 	    "ring %p ret %u wr_id %u oldest %u", ring, ret, wr_id, oldest);
189c0dd49bdSEiji Ota 	return (ret);
190c0dd49bdSEiji Ota }
191