LXR linux/drivers/staging/dgrp/dgrp_mon

   1/*****************************************************************************
   2 *
   3 * Copyright 1999 Digi International (www.digi.com)
   4 *     James Puzzo <jamesp at digi dot com>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2, or (at your option)
   9 * any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED; without even the
  13 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  14 * PURPOSE.  See the GNU General Public License for more details.
  15 *
  16 */
  17
  18/*
  19 *
  20 *  Filename:
  21 *
  22 *     dgrp_mon_ops.c
  23 *
  24 *  Description:
  25 *
  26 *     Handle the file operations required for the "monitor" devices.
  27 *     Includes those functions required to register the "mon" devices
  28 *     in "/proc".
  29 *
  30 *  Author:
  31 *
  32 *     James A. Puzzo
  33 *
  34 */
  35
  36#include <linux/module.h>
  37#include <linux/tty.h>
  38#include <linux/sched.h>
  39#include <asm/unaligned.h>
  40#include <linux/slab.h>
  41#include <linux/proc_fs.h>
  42#include <linux/uaccess.h>
  43
  44#include "dgrp_common.h"
  45
  46/* File operation declarations */
  47static int dgrp_mon_open(struct inode *, struct file *);
  48static int dgrp_mon_release(struct inode *, struct file *);
  49static ssize_t dgrp_mon_read(struct file *, char __user *, size_t, loff_t *);
  50static long dgrp_mon_ioctl(struct file *file, unsigned int cmd,
  51                           unsigned long arg);
  52
  53const struct file_operations dgrp_mon_ops = {
  54        .owner   = THIS_MODULE,
  55        .read    = dgrp_mon_read,
  56        .unlocked_ioctl = dgrp_mon_ioctl,
  57        .open    = dgrp_mon_open,
  58        .release = dgrp_mon_release,
  59};
  60
  61/**
  62 * dgrp_mon_open() -- open /proc/dgrp/ports device for a PortServer
  63 * @inode: struct inode *
  64 * @file: struct file *
  65 *
  66 * Open function to open the /proc/dgrp/ports device for a PortServer.
  67 */
  68static int dgrp_mon_open(struct inode *inode, struct file *file)
  69{
  70        struct nd_struct *nd;
  71        struct timeval tv;
  72        uint32_t time;
  73        u8 *buf;
  74        int rtn;
  75
  76        rtn = try_module_get(THIS_MODULE);
  77        if (!rtn)
  78                return -ENXIO;
  79
  80        rtn = 0;
  81
  82        if (!capable(CAP_SYS_ADMIN)) {
  83                rtn = -EPERM;
  84                goto done;
  85        }
  86
  87        /*
  88         *  Make sure that the "private_data" field hasn't already been used.
  89         */
  90        if (file->private_data) {
  91                rtn = -EINVAL;
  92                goto done;
  93        }
  94
  95        /*
  96         *  Get the node pointer, and fail if it doesn't exist.
  97         */
  98        nd = PDE_DATA(inode);
  99        if (!nd) {
 100                rtn = -ENXIO;
 101                goto done;
 102        }
 103
 104        file->private_data = (void *) nd;
 105
 106        /*
 107         * Allocate the monitor buffer.
 108         */
 109
 110        /*
 111         *  Grab the MON lock.
 112         */
 113        down(&nd->nd_mon_semaphore);
 114
 115        if (nd->nd_mon_buf) {
 116                rtn = -EBUSY;
 117                goto done_up;
 118        }
 119
 120        nd->nd_mon_buf = kmalloc(MON_MAX, GFP_KERNEL);
 121
 122        if (!nd->nd_mon_buf) {
 123                rtn = -ENOMEM;
 124                goto done_up;
 125        }
 126
 127        /*
 128         *  Enter an RPDUMP file header into the buffer.
 129         */
 130
 131        buf = nd->nd_mon_buf;
 132
 133        strcpy(buf, RPDUMP_MAGIC);
 134        buf += strlen(buf) + 1;
 135
 136        do_gettimeofday(&tv);
 137
 138        /*
 139         *  tv.tv_sec might be a 64 bit quantity.  Pare
 140         *  it down to 32 bits before attempting to encode
 141         *  it.
 142         */
 143        time = (uint32_t) (tv.tv_sec & 0xffffffff);
 144
 145        put_unaligned_be32(time, buf);
 146        put_unaligned_be16(0, buf + 4);
 147        buf += 6;
 148
 149        if (nd->nd_tx_module) {
 150                buf[0] = RPDUMP_CLIENT;
 151                put_unaligned_be32(0, buf + 1);
 152                put_unaligned_be16(1, buf + 5);
 153                buf[7] = 0xf0 + nd->nd_tx_module;
 154                buf += 8;
 155        }
 156
 157        if (nd->nd_rx_module) {
 158                buf[0] = RPDUMP_SERVER;
 159                put_unaligned_be32(0, buf + 1);
 160                put_unaligned_be16(1, buf + 5);
 161                buf[7] = 0xf0 + nd->nd_rx_module;
 162                buf += 8;
 163        }
 164
 165        nd->nd_mon_out = 0;
 166        nd->nd_mon_in  = buf - nd->nd_mon_buf;
 167        nd->nd_mon_lbolt = jiffies;
 168
 169done_up:
 170        up(&nd->nd_mon_semaphore);
 171
 172done:
 173        if (rtn)
 174                module_put(THIS_MODULE);
 175        return rtn;
 176}
 177
 178
 179/**
 180 * dgrp_mon_release() - Close the MON device for a particular PortServer
 181 * @inode: struct inode *
 182 * @file: struct file *
 183 */
 184static int dgrp_mon_release(struct inode *inode, struct file *file)
 185{
 186        struct nd_struct *nd;
 187
 188        /*
 189         *  Get the node pointer, and quit if it doesn't exist.
 190         */
 191        nd = (struct nd_struct *)(file->private_data);
 192        if (!nd)
 193                goto done;
 194
 195        /*
 196         *  Free the monitor buffer.
 197         */
 198
 199        down(&nd->nd_mon_semaphore);
 200
 201        kfree(nd->nd_mon_buf);
 202        nd->nd_mon_buf = NULL;
 203        nd->nd_mon_out = nd->nd_mon_in;
 204
 205        /*
 206         *  Wakeup any thread waiting for buffer space.
 207         */
 208
 209        if (nd->nd_mon_flag & MON_WAIT_SPACE) {
 210                nd->nd_mon_flag &= ~MON_WAIT_SPACE;
 211                wake_up_interruptible(&nd->nd_mon_wqueue);
 212        }
 213
 214        up(&nd->nd_mon_semaphore);
 215
 216        /*
 217         *  Make sure there is no thread in the middle of writing a packet.
 218         */
 219        down(&nd->nd_net_semaphore);
 220        up(&nd->nd_net_semaphore);
 221
 222done:
 223        module_put(THIS_MODULE);
 224        file->private_data = NULL;
 225        return 0;
 226}
 227
 228/**
 229 * dgrp_mon_read() -- Copy data from the monitoring buffer to the user
 230 */
 231static ssize_t dgrp_mon_read(struct file *file, char __user *buf, size_t count,
 232                             loff_t *ppos)
 233{
 234        struct nd_struct *nd;
 235        int r;
 236        int offset = 0;
 237        int res = 0;
 238        ssize_t rtn;
 239
 240        /*
 241         *  Get the node pointer, and quit if it doesn't exist.
 242         */
 243        nd = (struct nd_struct *)(file->private_data);
 244        if (!nd)
 245                return -ENXIO;
 246
 247        /*
 248         *  Wait for some data to appear in the buffer.
 249         */
 250
 251        down(&nd->nd_mon_semaphore);
 252
 253        for (;;) {
 254                res = (nd->nd_mon_in - nd->nd_mon_out) & MON_MASK;
 255
 256                if (res)
 257                        break;
 258
 259                nd->nd_mon_flag |= MON_WAIT_DATA;
 260
 261                up(&nd->nd_mon_semaphore);
 262
 263                /*
 264                 * Go to sleep waiting until the condition becomes true.
 265                 */
 266                rtn = wait_event_interruptible(nd->nd_mon_wqueue,
 267                                               ((nd->nd_mon_flag & MON_WAIT_DATA) == 0));
 268
 269                if (rtn)
 270                        return rtn;
 271
 272                down(&nd->nd_mon_semaphore);
 273        }
 274
 275        /*
 276         *  Read whatever is there.
 277         */
 278
 279        if (res > count)
 280                res = count;
 281
 282        r = MON_MAX - nd->nd_mon_out;
 283
 284        if (r <= res) {
 285                rtn = copy_to_user((void __user *)buf,
 286                                   nd->nd_mon_buf + nd->nd_mon_out, r);
 287                if (rtn) {
 288                        up(&nd->nd_mon_semaphore);
 289                        return -EFAULT;
 290                }
 291
 292                nd->nd_mon_out = 0;
 293                res -= r;
 294                offset = r;
 295        }
 296
 297        rtn = copy_to_user((void __user *) buf + offset,
 298                           nd->nd_mon_buf + nd->nd_mon_out, res);
 299        if (rtn) {
 300                up(&nd->nd_mon_semaphore);
 301                return -EFAULT;
 302        }
 303
 304        nd->nd_mon_out += res;
 305
 306        *ppos += res;
 307
 308        up(&nd->nd_mon_semaphore);
 309
 310        /*
 311         *  Wakeup any thread waiting for buffer space.
 312         */
 313
 314        if (nd->nd_mon_flag & MON_WAIT_SPACE) {
 315                nd->nd_mon_flag &= ~MON_WAIT_SPACE;
 316                wake_up_interruptible(&nd->nd_mon_wqueue);
 317        }
 318
 319        return res;
 320}
 321
 322/*  ioctl is not valid on monitor device */
 323static long dgrp_mon_ioctl(struct file *file, unsigned int cmd,
 324                           unsigned long arg)
 325{
 326        return -EINVAL;
 327}
 328