1 /*
2 * GPL HEADER START
3 *
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License
17 * version 2 along with this program; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 021110-1307, USA
20 *
21 * GPL HEADER END
22 */
23 /* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
24 * Copyright (c) 2012, Intel Corporation.
25 */
26 /*
27 * This file is part of Lustre, http://www.lustre.org/
28 * Lustre is a trademark of Sun Microsystems, Inc.
29 *
30 * Author: liang@whamcloud.com
31 */
32
33 #define DEBUG_SUBSYSTEM S_LNET
34
35 #include "../../include/linux/libcfs/libcfs.h"
36
37
38 /** destroy cpu-partition lock, see libcfs_private.h for more detail */
39 void
cfs_percpt_lock_free(struct cfs_percpt_lock * pcl)40 cfs_percpt_lock_free(struct cfs_percpt_lock *pcl)
41 {
42 LASSERT(pcl->pcl_locks != NULL);
43 LASSERT(!pcl->pcl_locked);
44
45 cfs_percpt_free(pcl->pcl_locks);
46 LIBCFS_FREE(pcl, sizeof(*pcl));
47 }
48 EXPORT_SYMBOL(cfs_percpt_lock_free);
49
50 /**
51 * create cpu-partition lock, see libcfs_private.h for more detail.
52 *
53 * cpu-partition lock is designed for large-scale SMP system, so we need to
54 * reduce cacheline conflict as possible as we can, that's the
55 * reason we always allocate cacheline-aligned memory block.
56 */
57 struct cfs_percpt_lock *
cfs_percpt_lock_alloc(struct cfs_cpt_table * cptab)58 cfs_percpt_lock_alloc(struct cfs_cpt_table *cptab)
59 {
60 struct cfs_percpt_lock *pcl;
61 spinlock_t *lock;
62 int i;
63
64 /* NB: cptab can be NULL, pcl will be for HW CPUs on that case */
65 LIBCFS_ALLOC(pcl, sizeof(*pcl));
66 if (pcl == NULL)
67 return NULL;
68
69 pcl->pcl_cptab = cptab;
70 pcl->pcl_locks = cfs_percpt_alloc(cptab, sizeof(*lock));
71 if (pcl->pcl_locks == NULL) {
72 LIBCFS_FREE(pcl, sizeof(*pcl));
73 return NULL;
74 }
75
76 cfs_percpt_for_each(lock, i, pcl->pcl_locks)
77 spin_lock_init(lock);
78
79 return pcl;
80 }
81 EXPORT_SYMBOL(cfs_percpt_lock_alloc);
82
83 /**
84 * lock a CPU partition
85 *
86 * \a index != CFS_PERCPT_LOCK_EX
87 * hold private lock indexed by \a index
88 *
89 * \a index == CFS_PERCPT_LOCK_EX
90 * exclusively lock @pcl and nobody can take private lock
91 */
92 void
cfs_percpt_lock(struct cfs_percpt_lock * pcl,int index)93 cfs_percpt_lock(struct cfs_percpt_lock *pcl, int index)
94 {
95 int ncpt = cfs_cpt_number(pcl->pcl_cptab);
96 int i;
97
98 LASSERT(index >= CFS_PERCPT_LOCK_EX && index < ncpt);
99
100 if (ncpt == 1) {
101 index = 0;
102 } else { /* serialize with exclusive lock */
103 while (pcl->pcl_locked)
104 cpu_relax();
105 }
106
107 if (likely(index != CFS_PERCPT_LOCK_EX)) {
108 spin_lock(pcl->pcl_locks[index]);
109 return;
110 }
111
112 /* exclusive lock request */
113 for (i = 0; i < ncpt; i++) {
114 spin_lock(pcl->pcl_locks[i]);
115 if (i == 0) {
116 LASSERT(!pcl->pcl_locked);
117 /* nobody should take private lock after this
118 * so I wouldn't starve for too long time */
119 pcl->pcl_locked = 1;
120 }
121 }
122 }
123 EXPORT_SYMBOL(cfs_percpt_lock);
124
125 /** unlock a CPU partition */
126 void
cfs_percpt_unlock(struct cfs_percpt_lock * pcl,int index)127 cfs_percpt_unlock(struct cfs_percpt_lock *pcl, int index)
128 {
129 int ncpt = cfs_cpt_number(pcl->pcl_cptab);
130 int i;
131
132 index = ncpt == 1 ? 0 : index;
133
134 if (likely(index != CFS_PERCPT_LOCK_EX)) {
135 spin_unlock(pcl->pcl_locks[index]);
136 return;
137 }
138
139 for (i = ncpt - 1; i >= 0; i--) {
140 if (i == 0) {
141 LASSERT(pcl->pcl_locked);
142 pcl->pcl_locked = 0;
143 }
144 spin_unlock(pcl->pcl_locks[i]);
145 }
146 }
147 EXPORT_SYMBOL(cfs_percpt_unlock);
148
149
150 /** free cpu-partition refcount */
151 void
cfs_percpt_atomic_free(atomic_t ** refs)152 cfs_percpt_atomic_free(atomic_t **refs)
153 {
154 cfs_percpt_free(refs);
155 }
156 EXPORT_SYMBOL(cfs_percpt_atomic_free);
157
158 /** allocate cpu-partition refcount with initial value @init_val */
159 atomic_t **
cfs_percpt_atomic_alloc(struct cfs_cpt_table * cptab,int init_val)160 cfs_percpt_atomic_alloc(struct cfs_cpt_table *cptab, int init_val)
161 {
162 atomic_t **refs;
163 atomic_t *ref;
164 int i;
165
166 refs = cfs_percpt_alloc(cptab, sizeof(*ref));
167 if (refs == NULL)
168 return NULL;
169
170 cfs_percpt_for_each(ref, i, refs)
171 atomic_set(ref, init_val);
172 return refs;
173 }
174 EXPORT_SYMBOL(cfs_percpt_atomic_alloc);
175
176 /** return sum of cpu-partition refs */
177 int
cfs_percpt_atomic_summary(atomic_t ** refs)178 cfs_percpt_atomic_summary(atomic_t **refs)
179 {
180 atomic_t *ref;
181 int i;
182 int val = 0;
183
184 cfs_percpt_for_each(ref, i, refs)
185 val += atomic_read(ref);
186
187 return val;
188 }
189 EXPORT_SYMBOL(cfs_percpt_atomic_summary);
190