subr_counter.c revision 252434 
1/*-
2 * Copyright (c) 2012 Gleb Smirnoff <glebius@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/kern/subr_counter.c 252434 2013-07-01 02:48:27Z kib $");
29
30#include <sys/param.h>
31#include <sys/systm.h>
32#include <sys/kernel.h>
33#include <sys/lock.h>
34#include <sys/mutex.h>
35#include <sys/proc.h>
36#include <sys/sched.h>
37#include <sys/smp.h>
38#include <sys/sysctl.h>
39#include <vm/uma.h>
40
41#define IN_SUBR_COUNTER_C
42#include <sys/counter.h>
43
44static uma_zone_t uint64_pcpu_zone;
45
46void
47counter_u64_zero(counter_u64_t c)
48{
49
50	counter_u64_zero_inline(c);
51}
52
53uint64_t
54counter_u64_fetch(counter_u64_t c)
55{
56
57	return (counter_u64_fetch_inline(c));
58}
59
60counter_u64_t
61counter_u64_alloc(int flags)
62{
63	counter_u64_t r;
64
65	r = uma_zalloc(uint64_pcpu_zone, flags);
66	if (r != NULL)
67		counter_u64_zero(r);
68
69	return (r);
70}
71
72void
73counter_u64_free(counter_u64_t c)
74{
75
76	uma_zfree(uint64_pcpu_zone, c);
77}
78
79int
80sysctl_handle_counter_u64(SYSCTL_HANDLER_ARGS)
81{
82	uint64_t out;
83	int error;
84
85	out = counter_u64_fetch(*(counter_u64_t *)arg1);
86
87	error = SYSCTL_OUT(req, &out, sizeof(uint64_t));
88
89	if (error || !req->newptr)
90		return (error);
91
92	/*
93	 * Any write attempt to a counter zeroes it.
94	 */
95	counter_u64_zero(*(counter_u64_t *)arg1);
96
97	return (0);
98}
99
100static void
101counter_startup(void)
102{
103
104	uint64_pcpu_zone = uma_zcreate("uint64 pcpu", sizeof(uint64_t),
105	    NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_PCPU);
106}
107SYSINIT(counter, SI_SUB_CPU, SI_ORDER_FOURTH, counter_startup, NULL);
108