Phonet: proc interface for port range
[linux-2.6.git] / net / phonet / sysctl.c
1 /*
2  * File: sysctl.c
3  *
4  * Phonet /proc/sys/net/phonet interface implementation
5  *
6  * Copyright (C) 2008 Nokia Corporation.
7  *
8  * Contact: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License
12  * version 2 as published by the Free Software Foundation.
13  *
14  * This program is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17  * General Public License for more details.
18  *
19  * You should have received a copy of the GNU General Public License
20  * along with this program; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22  * 02110-1301 USA
23  */
24
25 #include <linux/seqlock.h>
26 #include <linux/sysctl.h>
27 #include <linux/errno.h>
28 #include <linux/init.h>
29
30 #define DYNAMIC_PORT_MIN        0x40
31 #define DYNAMIC_PORT_MAX        0x7f
32
33 static DEFINE_SEQLOCK(local_port_range_lock);
34 static int local_port_range_min[2] = {0, 0};
35 static int local_port_range_max[2] = {1023, 1023};
36 static int local_port_range[2] = {DYNAMIC_PORT_MIN, DYNAMIC_PORT_MAX};
37 static struct ctl_table_header *phonet_table_hrd;
38
39 static void set_local_port_range(int range[2])
40 {
41         write_seqlock(&local_port_range_lock);
42         local_port_range[0] = range[0];
43         local_port_range[1] = range[1];
44         write_sequnlock(&local_port_range_lock);
45 }
46
47 void phonet_get_local_port_range(int *min, int *max)
48 {
49         unsigned seq;
50         do {
51                 seq = read_seqbegin(&local_port_range_lock);
52                 if (min)
53                         *min = local_port_range[0];
54                 if (max)
55                         *max = local_port_range[1];
56         } while (read_seqretry(&local_port_range_lock, seq));
57 }
58
59 static int proc_local_port_range(ctl_table *table, int write, struct file *filp,
60                                 void __user *buffer,
61                                 size_t *lenp, loff_t *ppos)
62 {
63         int ret;
64         int range[2] = {local_port_range[0], local_port_range[1]};
65         ctl_table tmp = {
66                 .data = &range,
67                 .maxlen = sizeof(range),
68                 .mode = table->mode,
69                 .extra1 = &local_port_range_min,
70                 .extra2 = &local_port_range_max,
71         };
72
73         ret = proc_dointvec_minmax(&tmp, write, filp, buffer, lenp, ppos);
74
75         if (write && ret == 0) {
76                 if (range[1] < range[0])
77                         ret = -EINVAL;
78                 else
79                         set_local_port_range(range);
80         }
81
82         return ret;
83 }
84
85 static struct ctl_table phonet_table[] = {
86         {
87                 .ctl_name       = CTL_UNNUMBERED,
88                 .procname       = "local_port_range",
89                 .data           = &local_port_range,
90                 .maxlen         = sizeof(local_port_range),
91                 .mode           = 0644,
92                 .proc_handler   = &proc_local_port_range,
93                 .strategy       = NULL,
94         },
95         { .ctl_name = 0 }
96 };
97
98 struct ctl_path phonet_ctl_path[] = {
99         { .procname = "net", .ctl_name = CTL_NET, },
100         { .procname = "phonet", .ctl_name = CTL_UNNUMBERED, },
101         { },
102 };
103
104 int __init phonet_sysctl_init(void)
105 {
106         phonet_table_hrd = register_sysctl_paths(phonet_ctl_path, phonet_table);
107         return phonet_table_hrd == NULL ? -ENOMEM : 0;
108 }
109
110 void phonet_sysctl_exit(void)
111 {
112         unregister_sysctl_table(phonet_table_hrd);
113 }