1// SPDX-License-Identifier: GPL-2.0
2/*
3 * The USB Monitor, inspired by Dave Harding's USBMon.
4 *
5 * This is the 's' or 'stat' reader which debugs usbmon itself.
6 * Note that this code blows through locks, so make sure that
7 * /dbg/usbmon/0s is well protected from non-root users.
8 *
9 */
10
11#include <linux/kernel.h>
12#include <linux/slab.h>
13#include <linux/export.h>
14#include <linux/usb.h>
15#include <linux/fs.h>
16#include <linux/uaccess.h>
17
18#include "usb_mon.h"
19
20#define STAT_BUF_SIZE 80
21
22struct snap {
23 int slen;
24 char str[STAT_BUF_SIZE];
25};
26
27static int mon_stat_open(struct inode *inode, struct file *file)
28{
29 struct mon_bus *mbus;
30 struct snap *sp;
31
32 sp = kmalloc(sizeof(struct snap), GFP_KERNEL);
33 if (sp == NULL)
34 return -ENOMEM;
35
36 mbus = inode->i_private;
37
38 sp->slen = scnprintf(buf: sp->str, STAT_BUF_SIZE,
39 fmt: "nreaders %d events %u text_lost %u\n",
40 mbus->nreaders, mbus->cnt_events, mbus->cnt_text_lost);
41
42 file->private_data = sp;
43 return 0;
44}
45
46static ssize_t mon_stat_read(struct file *file, char __user *buf,
47 size_t nbytes, loff_t *ppos)
48{
49 struct snap *sp = file->private_data;
50
51 return simple_read_from_buffer(to: buf, count: nbytes, ppos, from: sp->str, available: sp->slen);
52}
53
54static int mon_stat_release(struct inode *inode, struct file *file)
55{
56 struct snap *sp = file->private_data;
57 file->private_data = NULL;
58 kfree(objp: sp);
59 return 0;
60}
61
62const struct file_operations mon_fops_stat = {
63 .owner = THIS_MODULE,
64 .open = mon_stat_open,
65 .read = mon_stat_read,
66 /* .write = mon_stat_write, */
67 /* .poll = mon_stat_poll, */
68 /* .unlocked_ioctl = mon_stat_ioctl, */
69 .release = mon_stat_release,
70};
71