LXR linux/drivers/usb/mon/mon

   1/*
   2 * The USB Monitor, inspired by Dave Harding's USBMon.
   3 *
   4 * This is the 's' or 'stat' reader which debugs usbmon itself.
   5 * Note that this code blows through locks, so make sure that
   6 * /dbg/usbmon/0s is well protected from non-root users.
   7 *
   8 */
   9
  10#include <linux/kernel.h>
  11#include <linux/slab.h>
  12#include <linux/export.h>
  13#include <linux/usb.h>
  14#include <linux/fs.h>
  15#include <asm/uaccess.h>
  16
  17#include "usb_mon.h"
  18
  19#define STAT_BUF_SIZE  80
  20
  21struct snap {
  22        int slen;
  23        char str[STAT_BUF_SIZE];
  24};
  25
  26static int mon_stat_open(struct inode *inode, struct file *file)
  27{
  28        struct mon_bus *mbus;
  29        struct snap *sp;
  30
  31        if ((sp = kmalloc(sizeof(struct snap), GFP_KERNEL)) == NULL)
  32                return -ENOMEM;
  33
  34        mbus = inode->i_private;
  35
  36        sp->slen = snprintf(sp->str, STAT_BUF_SIZE,
  37            "nreaders %d events %u text_lost %u\n",
  38            mbus->nreaders, mbus->cnt_events, mbus->cnt_text_lost);
  39
  40        file->private_data = sp;
  41        return 0;
  42}
  43
  44static ssize_t mon_stat_read(struct file *file, char __user *buf,
  45                                size_t nbytes, loff_t *ppos)
  46{
  47        struct snap *sp = file->private_data;
  48
  49        return simple_read_from_buffer(buf, nbytes, ppos, sp->str, sp->slen);
  50}
  51
  52static int mon_stat_release(struct inode *inode, struct file *file)
  53{
  54        struct snap *sp = file->private_data;
  55        file->private_data = NULL;
  56        kfree(sp);
  57        return 0;
  58}
  59
  60const struct file_operations mon_fops_stat = {
  61        .owner =        THIS_MODULE,
  62        .open =         mon_stat_open,
  63        .llseek =       no_llseek,
  64        .read =         mon_stat_read,
  65        /* .write =     mon_stat_write, */
  66        /* .poll =              mon_stat_poll, */
  67        /* .unlocked_ioctl =    mon_stat_ioctl, */
  68        .release =      mon_stat_release,
  69};
  70