root/net/phonet/sysctl.c

DEFINITIONS

1. set_local_port_range
2. phonet_get_local_port_range
3. proc_local_port_range
4. phonet_sysctl_init
5. phonet_sysctl_exit

/*
 * File: sysctl.c
 *
 * Phonet /proc/sys/net/phonet interface implementation
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Contact: Remi Denis-Courmont <remi.denis-courmont@nokia.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/seqlock.h>
#include <linux/sysctl.h>
#include <linux/errno.h>
#include <linux/init.h>

#define DYNAMIC_PORT_MIN        0x40
#define DYNAMIC_PORT_MAX        0x7f

static DEFINE_SEQLOCK(local_port_range_lock);
static int local_port_range_min[2] = {0, 0};
static int local_port_range_max[2] = {1023, 1023};
static int local_port_range[2] = {DYNAMIC_PORT_MIN, DYNAMIC_PORT_MAX};
static struct ctl_table_header *phonet_table_hrd;

static void set_local_port_range(int range[2])
{
        write_seqlock(&local_port_range_lock);
        local_port_range[0] = range[0];
        local_port_range[1] = range[1];
        write_sequnlock(&local_port_range_lock);
}

void phonet_get_local_port_range(int *min, int *max)
{
        unsigned seq;
        do {
                seq = read_seqbegin(&local_port_range_lock);
                if (min)
                        *min = local_port_range[0];
                if (max)
                        *max = local_port_range[1];
        } while (read_seqretry(&local_port_range_lock, seq));
}

static int proc_local_port_range(ctl_table *table, int write, struct file *filp,
                                void __user *buffer,
                                size_t *lenp, loff_t *ppos)
{
        int ret;
        int range[2] = {local_port_range[0], local_port_range[1]};
        ctl_table tmp = {
                .data = &range,
                .maxlen = sizeof(range),
                .mode = table->mode,
                .extra1 = &local_port_range_min,
                .extra2 = &local_port_range_max,
        };

        ret = proc_dointvec_minmax(&tmp, write, filp, buffer, lenp, ppos);

        if (write && ret == 0) {
                if (range[1] < range[0])
                        ret = -EINVAL;
                else
                        set_local_port_range(range);
        }

        return ret;
}

static struct ctl_table phonet_table[] = {
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "local_port_range",
                .data           = &local_port_range,
                .maxlen         = sizeof(local_port_range),
                .mode           = 0644,
                .proc_handler   = &proc_local_port_range,
                .strategy       = NULL,
        },
        { .ctl_name = 0 }
};

struct ctl_path phonet_ctl_path[] = {
        { .procname = "net", .ctl_name = CTL_NET, },
        { .procname = "phonet", .ctl_name = CTL_UNNUMBERED, },
        { },
};

int __init phonet_sysctl_init(void)
{
        phonet_table_hrd = register_sysctl_paths(phonet_ctl_path, phonet_table);
        return phonet_table_hrd == NULL ? -ENOMEM : 0;
}

void phonet_sysctl_exit(void)
{
        unregister_sysctl_table(phonet_table_hrd);
}