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/usb.h>
  13#include <linux/fs.h>
  14#include <asm/uaccess.h>
  15
  16#include "usb_mon.h"
  17
  18#define STAT_BUF_SIZE  80
  19
  20struct snap {
  21        int slen;
  22        char str[STAT_BUF_SIZE];
  23};
  24
  25static int mon_stat_open(struct inode *inode, struct file *file)
  26{
  27        struct mon_bus *mbus;
  28        struct snap *sp;
  29
  30        if ((sp = kmalloc(sizeof(struct snap), GFP_KERNEL)) == NULL)
  31                return -ENOMEM;
  32
  33        mbus = inode->i_private;
  34
  35        sp->slen = snprintf(sp->str, STAT_BUF_SIZE,
  36            "nreaders %d events %u text_lost %u\n",
  37            mbus->nreaders, mbus->cnt_events, mbus->cnt_text_lost);
  38
  39        file->private_data = sp;
  40        return 0;
  41}
  42
  43static ssize_t mon_stat_read(struct file *file, char __user *buf,
  44                                size_t nbytes, loff_t *ppos)
  45{
  46        struct snap *sp = file->private_data;
  47
  48        return simple_read_from_buffer(buf, nbytes, ppos, sp->str, sp->slen);
  49}
  50
  51static int mon_stat_release(struct inode *inode, struct file *file)
  52{
  53        struct snap *sp = file->private_data;
  54        file->private_data = NULL;
  55        kfree(sp);
  56        return 0;
  57}
  58
  59const struct file_operations mon_fops_stat = {
  60        .owner =        THIS_MODULE,
  61        .open =         mon_stat_open,
  62        .llseek =       no_llseek,
  63        .read =         mon_stat_read,
  64        /* .write =     mon_stat_write, */
  65        /* .poll =              mon_stat_poll, */
  66        /* .unlocked_ioctl =    mon_stat_ioctl, */
  67        .release =      mon_stat_release,
  68};
  69