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