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 20 struct snap { 21 int slen; 22 char str[STAT_BUF_SIZE]; 23 }; 24 25 static 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 43 static 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 51 static 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 59 const 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