1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2012 Gleb Smirnoff <glebius@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/kernel.h>
32 #include <sys/lock.h>
33 #include <sys/mutex.h>
34 #include <sys/proc.h>
35 #include <sys/sched.h>
36 #include <sys/smp.h>
37 #include <sys/sysctl.h>
38 #include <vm/uma.h>
39
40 #define IN_SUBR_COUNTER_C
41 #include <sys/counter.h>
42
43 static MALLOC_DEFINE(M_COUNTER_RATE, "counter_rate", "counter rate allocations");
44
45 void
counter_u64_zero(counter_u64_t c)46 counter_u64_zero(counter_u64_t c)
47 {
48
49 counter_u64_zero_inline(c);
50 }
51
52 uint64_t
counter_u64_fetch(counter_u64_t c)53 counter_u64_fetch(counter_u64_t c)
54 {
55
56 return (counter_u64_fetch_inline(c));
57 }
58
59 counter_u64_t
counter_u64_alloc(int flags)60 counter_u64_alloc(int flags)
61 {
62
63 return (uma_zalloc_pcpu(pcpu_zone_8, flags | M_ZERO));
64 }
65
66 void
counter_u64_free(counter_u64_t c)67 counter_u64_free(counter_u64_t c)
68 {
69
70 uma_zfree_pcpu(pcpu_zone_8, c);
71 }
72
73 int
sysctl_handle_counter_u64(SYSCTL_HANDLER_ARGS)74 sysctl_handle_counter_u64(SYSCTL_HANDLER_ARGS)
75 {
76 uint64_t out;
77 int error;
78
79 out = counter_u64_fetch(*(counter_u64_t *)arg1);
80
81 error = SYSCTL_OUT(req, &out, sizeof(uint64_t));
82
83 if (error || !req->newptr)
84 return (error);
85
86 /*
87 * Any write attempt to a counter zeroes it.
88 */
89 counter_u64_zero(*(counter_u64_t *)arg1);
90
91 return (0);
92 }
93
94 int
sysctl_handle_counter_u64_array(SYSCTL_HANDLER_ARGS)95 sysctl_handle_counter_u64_array(SYSCTL_HANDLER_ARGS)
96 {
97 uint64_t *out;
98 int error;
99
100 out = malloc(arg2 * sizeof(uint64_t), M_TEMP, M_WAITOK);
101 for (int i = 0; i < arg2; i++)
102 out[i] = counter_u64_fetch(((counter_u64_t *)arg1)[i]);
103
104 error = SYSCTL_OUT(req, out, arg2 * sizeof(uint64_t));
105 free(out, M_TEMP);
106
107 if (error || !req->newptr)
108 return (error);
109
110 /*
111 * Any write attempt to a counter zeroes it.
112 */
113 for (int i = 0; i < arg2; i++)
114 counter_u64_zero(((counter_u64_t *)arg1)[i]);
115
116 return (0);
117 }
118
119 /*
120 * counter(9) based rate checking.
121 */
122 struct counter_rate {
123 counter_u64_t cr_rate; /* Events since last second */
124 volatile int cr_lock; /* Lock to clean the struct */
125 int cr_ticks; /* Ticks on last clean */
126 int cr_over; /* Over limit since cr_ticks? */
127 int cr_period; /* Allow cr_rate per cr_period seconds. */
128 };
129
130 struct counter_rate *
counter_rate_alloc(int flags,int period)131 counter_rate_alloc(int flags, int period)
132 {
133 struct counter_rate *new;
134
135 new = malloc(sizeof(struct counter_rate), M_COUNTER_RATE,
136 flags | M_ZERO);
137 if (new == NULL)
138 return (NULL);
139
140 new->cr_rate = counter_u64_alloc(flags);
141 if (new->cr_rate == NULL) {
142 free(new, M_COUNTER_RATE);
143 return (NULL);
144 }
145 new->cr_ticks = ticks;
146 new->cr_period = period;
147
148 return (new);
149 }
150
151 void
counter_rate_free(struct counter_rate * rate)152 counter_rate_free(struct counter_rate *rate)
153 {
154 if (rate == NULL)
155 return;
156
157 counter_u64_free(rate->cr_rate);
158 free(rate, M_COUNTER_RATE);
159 }
160
161 uint64_t
counter_rate_get(struct counter_rate * cr)162 counter_rate_get(struct counter_rate *cr)
163 {
164 if (cr->cr_ticks < (tick - (hz * cr->cr_period)))
165 return (0);
166
167 return (counter_u64_fetch(cr->cr_rate));
168 }
169
170 /*
171 * MP-friendly version of ppsratecheck().
172 *
173 * Returns non-negative if we are in the rate, negative otherwise.
174 * 0 - rate limit not reached.
175 * -1 - rate limit reached.
176 * >0 - rate limit was reached before, and was just reset. The return value
177 * is number of events since last reset.
178 */
179 int64_t
counter_ratecheck(struct counter_rate * cr,int64_t limit)180 counter_ratecheck(struct counter_rate *cr, int64_t limit)
181 {
182 int64_t val;
183 int now;
184
185 val = cr->cr_over;
186 now = ticks;
187
188 if ((u_int)(now - cr->cr_ticks) >= (hz * cr->cr_period)) {
189 /*
190 * Time to clear the structure, we are in the next second.
191 * First try unlocked read, and then proceed with atomic.
192 */
193 if ((cr->cr_lock == 0) &&
194 atomic_cmpset_acq_int(&cr->cr_lock, 0, 1)) {
195 /*
196 * Check if other thread has just went through the
197 * reset sequence before us.
198 */
199 if ((u_int)(now - cr->cr_ticks) >= (hz * cr->cr_period)) {
200 val = counter_u64_fetch(cr->cr_rate);
201 counter_u64_zero(cr->cr_rate);
202 cr->cr_over = 0;
203 cr->cr_ticks = now;
204 if (val <= limit)
205 val = 0;
206 }
207 atomic_store_rel_int(&cr->cr_lock, 0);
208 } else
209 /*
210 * We failed to lock, in this case other thread may
211 * be running counter_u64_zero(), so it is not safe
212 * to do an update, we skip it.
213 */
214 return (val);
215 }
216
217 counter_u64_add(cr->cr_rate, 1);
218 if (cr->cr_over != 0)
219 return (-1);
220 if (counter_u64_fetch(cr->cr_rate) > limit)
221 val = cr->cr_over = -1;
222
223 return (val);
224 }
225
226 void
counter_u64_sysinit(void * arg)227 counter_u64_sysinit(void *arg)
228 {
229 counter_u64_t *cp;
230
231 cp = arg;
232 *cp = counter_u64_alloc(M_WAITOK);
233 }
234
235 void
counter_u64_sysuninit(void * arg)236 counter_u64_sysuninit(void *arg)
237 {
238 counter_u64_t *cp;
239
240 cp = arg;
241 counter_u64_free(*cp);
242 }
243