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 21 struct snap { 22 int slen; 23 char str[STAT_BUF_SIZE]; 24 }; 25 26 static 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 44 static 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 52 static 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 60 const 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