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, see
18 * http://www.gnu.org/licenses/gpl-2.0.html
19 *
20 * GPL HEADER END
21 */
22 /*
23 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
25 *
26 * Copyright (c) 2011, 2012, Intel Corporation.
27 */
28 /*
29 * This file is part of Lustre, http://www.lustre.org/
30 * Lustre is a trademark of Sun Microsystems, Inc.
31 *
32 * lnet/selftest/timer.c
33 *
34 * Author: Isaac Huang <isaac@clusterfs.com>
35 */
36
37 #define DEBUG_SUBSYSTEM S_LNET
38
39 #include "selftest.h"
40
41 /*
42 * Timers are implemented as a sorted queue of expiry times. The queue
43 * is slotted, with each slot holding timers which expire in a
44 * 2**STTIMER_MINPOLL (8) second period. The timers in each slot are
45 * sorted by increasing expiry time. The number of slots is 2**7 (128),
46 * to cover a time period of 1024 seconds into the future before wrapping.
47 */
48 #define STTIMER_MINPOLL 3 /* log2 min poll interval (8 s) */
49 #define STTIMER_SLOTTIME (1 << STTIMER_MINPOLL)
50 #define STTIMER_SLOTTIMEMASK (~(STTIMER_SLOTTIME - 1))
51 #define STTIMER_NSLOTS (1 << 7)
52 #define STTIMER_SLOT(t) (&stt_data.stt_hash[(((t) >> STTIMER_MINPOLL) & \
53 (STTIMER_NSLOTS - 1))])
54
55 static struct st_timer_data {
56 spinlock_t stt_lock;
57 unsigned long stt_prev_slot; /* start time of the slot processed
58 * previously */
59 struct list_head stt_hash[STTIMER_NSLOTS];
60 int stt_shuttingdown;
61 wait_queue_head_t stt_waitq;
62 int stt_nthreads;
63 } stt_data;
64
65 void
stt_add_timer(struct stt_timer * timer)66 stt_add_timer(struct stt_timer *timer)
67 {
68 struct list_head *pos;
69
70 spin_lock(&stt_data.stt_lock);
71
72 LASSERT(stt_data.stt_nthreads > 0);
73 LASSERT(!stt_data.stt_shuttingdown);
74 LASSERT(timer->stt_func);
75 LASSERT(list_empty(&timer->stt_list));
76 LASSERT(timer->stt_expires > ktime_get_real_seconds());
77
78 /* a simple insertion sort */
79 list_for_each_prev(pos, STTIMER_SLOT(timer->stt_expires)) {
80 struct stt_timer *old = list_entry(pos, struct stt_timer,
81 stt_list);
82
83 if (timer->stt_expires >= old->stt_expires)
84 break;
85 }
86 list_add(&timer->stt_list, pos);
87
88 spin_unlock(&stt_data.stt_lock);
89 }
90
91 /*
92 * The function returns whether it has deactivated a pending timer or not.
93 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
94 * active timer returns 1.)
95 *
96 * CAVEAT EMPTOR:
97 * When 0 is returned, it is possible that timer->stt_func _is_ running on
98 * another CPU.
99 */
100 int
stt_del_timer(struct stt_timer * timer)101 stt_del_timer(struct stt_timer *timer)
102 {
103 int ret = 0;
104
105 spin_lock(&stt_data.stt_lock);
106
107 LASSERT(stt_data.stt_nthreads > 0);
108 LASSERT(!stt_data.stt_shuttingdown);
109
110 if (!list_empty(&timer->stt_list)) {
111 ret = 1;
112 list_del_init(&timer->stt_list);
113 }
114
115 spin_unlock(&stt_data.stt_lock);
116 return ret;
117 }
118
119 /* called with stt_data.stt_lock held */
120 static int
stt_expire_list(struct list_head * slot,time64_t now)121 stt_expire_list(struct list_head *slot, time64_t now)
122 {
123 int expired = 0;
124 struct stt_timer *timer;
125
126 while (!list_empty(slot)) {
127 timer = list_entry(slot->next, struct stt_timer, stt_list);
128
129 if (timer->stt_expires > now)
130 break;
131
132 list_del_init(&timer->stt_list);
133 spin_unlock(&stt_data.stt_lock);
134
135 expired++;
136 (*timer->stt_func) (timer->stt_data);
137
138 spin_lock(&stt_data.stt_lock);
139 }
140
141 return expired;
142 }
143
144 static int
stt_check_timers(unsigned long * last)145 stt_check_timers(unsigned long *last)
146 {
147 int expired = 0;
148 time64_t now;
149 unsigned long this_slot;
150
151 now = ktime_get_real_seconds();
152 this_slot = now & STTIMER_SLOTTIMEMASK;
153
154 spin_lock(&stt_data.stt_lock);
155
156 while (cfs_time_aftereq(this_slot, *last)) {
157 expired += stt_expire_list(STTIMER_SLOT(this_slot), now);
158 this_slot = cfs_time_sub(this_slot, STTIMER_SLOTTIME);
159 }
160
161 *last = now & STTIMER_SLOTTIMEMASK;
162 spin_unlock(&stt_data.stt_lock);
163 return expired;
164 }
165
166 static int
stt_timer_main(void * arg)167 stt_timer_main(void *arg)
168 {
169 int rc = 0;
170
171 cfs_block_allsigs();
172
173 while (!stt_data.stt_shuttingdown) {
174 stt_check_timers(&stt_data.stt_prev_slot);
175
176 rc = wait_event_timeout(stt_data.stt_waitq,
177 stt_data.stt_shuttingdown,
178 cfs_time_seconds(STTIMER_SLOTTIME));
179 }
180
181 spin_lock(&stt_data.stt_lock);
182 stt_data.stt_nthreads--;
183 spin_unlock(&stt_data.stt_lock);
184 return rc;
185 }
186
187 static int
stt_start_timer_thread(void)188 stt_start_timer_thread(void)
189 {
190 struct task_struct *task;
191
192 LASSERT(!stt_data.stt_shuttingdown);
193
194 task = kthread_run(stt_timer_main, NULL, "st_timer");
195 if (IS_ERR(task))
196 return PTR_ERR(task);
197
198 spin_lock(&stt_data.stt_lock);
199 stt_data.stt_nthreads++;
200 spin_unlock(&stt_data.stt_lock);
201 return 0;
202 }
203
204 int
stt_startup(void)205 stt_startup(void)
206 {
207 int rc = 0;
208 int i;
209
210 stt_data.stt_shuttingdown = 0;
211 stt_data.stt_prev_slot = ktime_get_real_seconds() & STTIMER_SLOTTIMEMASK;
212
213 spin_lock_init(&stt_data.stt_lock);
214 for (i = 0; i < STTIMER_NSLOTS; i++)
215 INIT_LIST_HEAD(&stt_data.stt_hash[i]);
216
217 stt_data.stt_nthreads = 0;
218 init_waitqueue_head(&stt_data.stt_waitq);
219 rc = stt_start_timer_thread();
220 if (rc)
221 CERROR("Can't spawn timer thread: %d\n", rc);
222
223 return rc;
224 }
225
226 void
stt_shutdown(void)227 stt_shutdown(void)
228 {
229 int i;
230
231 spin_lock(&stt_data.stt_lock);
232
233 for (i = 0; i < STTIMER_NSLOTS; i++)
234 LASSERT(list_empty(&stt_data.stt_hash[i]));
235
236 stt_data.stt_shuttingdown = 1;
237
238 wake_up(&stt_data.stt_waitq);
239 lst_wait_until(!stt_data.stt_nthreads, stt_data.stt_lock,
240 "waiting for %d threads to terminate\n",
241 stt_data.stt_nthreads);
242
243 spin_unlock(&stt_data.stt_lock);
244 }
245