linux/net/phonet/sysctl.c
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   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
  33static DEFINE_SEQLOCK(local_port_range_lock);
  34static int local_port_range_min[2] = {0, 0};
  35static int local_port_range_max[2] = {1023, 1023};
  36static int local_port_range[2] = {DYNAMIC_PORT_MIN, DYNAMIC_PORT_MAX};
  37static struct ctl_table_header *phonet_table_hrd;
  38
  39static 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
  47void 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
  59static 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
  85static 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
  98static struct ctl_path phonet_ctl_path[] = {
  99        { .procname = "net", .ctl_name = CTL_NET, },
 100        { .procname = "phonet", .ctl_name = CTL_UNNUMBERED, },
 101        { },
 102};
 103
 104int __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
 110void phonet_sysctl_exit(void)
 111{
 112        unregister_sysctl_table(phonet_table_hrd);
 113}
 114