/*
* The USB Monitor, inspired by Dave Harding's USBMon.
*
* mon_main.c: Main file, module initiation and exit, registrations, etc.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/debugfs.h>
#include <linux/smp_lock.h>
#include "usb_mon.h"
#include "../core/hcd.h"
static void mon_submit(struct usb_bus *ubus, struct urb *urb);
static void mon_complete(struct usb_bus *ubus, struct urb *urb);
static void mon_stop(struct mon_bus *mbus);
static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus);
static void mon_bus_drop(struct kref *r);
static void mon_bus_init(struct dentry *mondir, struct usb_bus *ubus);
DECLARE_MUTEX(mon_lock);
static struct dentry *mon_dir; /* /dbg/usbmon */
static LIST_HEAD(mon_buses); /* All buses we know: struct mon_bus */
/*
* Link a reader into the bus.
*
* This must be called with mon_lock taken because of mbus->ref.
*/
void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r)
{
unsigned long flags;
struct usb_bus *ubus;
spin_lock_irqsave(&mbus->lock, flags);
if (mbus->nreaders == 0) {
ubus = mbus->u_bus;
if (ubus->monitored) {
/*
* Something is really broken, refuse to go on and
* possibly corrupt ops pointers or worse.
*/
printk(KERN_ERR TAG ": bus %d is already monitored\n",
ubus->busnum);
spin_unlock_irqrestore(&mbus->lock, flags);
return;
}
ubus->monitored = 1;
}
mbus->nreaders++;
list_add_tail(&r->r_link, &mbus->r_list);
spin_unlock_irqrestore(&mbus->lock, flags);
kref_get(&mbus->ref);
}
/*
* Unlink reader from the bus.
*
* This is called with mon_lock taken, so we can decrement mbus->ref.
*/
void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r)
{
unsigned long flags;
spin_lock_irqsave(&mbus->lock, flags);
list_del(&r->r_link);
--mbus->nreaders;
if (mbus->nreaders == 0)
mon_stop(mbus);
spin_unlock_irqrestore(&mbus->lock, flags);
kref_put(&mbus->ref, mon_bus_drop);
}
/*
*/
static void mon_submit(struct usb_bus *ubus, struct urb *urb)
{
struct mon_bus *mbus;
unsigned long flags;
struct list_head *pos;
struct mon_reader *r;
mbus = ubus->mon_bus;
if (mbus == NULL)
goto out_unlocked;
spin_lock_irqsave(&mbus->lock, flags);
if (mbus->nreaders == 0)
goto out_locked;
list_for_each (pos, &mbus->r_list) {
r = list_entry(pos, struct mon_reader, r_link);
r->rnf_submit(r->r_data, urb);
}
spin_unlock_irqrestore(&mbus->lock, flags);
return;
out_locked:
spin_unlock_irqrestore(&mbus->lock, flags);
out_unlocked:
return;
}
/*
*/
static void mon_submit_error(struct usb_bus *ubus, struct urb *urb, int err)
{
struct mon_bus *mbus;
mbus = ubus->mon_bus;
if (mbus == NULL)
goto out_unlocked;
/*
* XXX Capture the error code and the 'E' event.
*/
return;
out_unlocked:
return;
}
/*
*/
static void mon_complete(struct usb_bus *ubus, struct urb *urb)
{
struct mon_bus *mbus;
unsigned long flags;
struct list_head *pos;
struct mon_reader *r;
mbus = ubus->mon_bus;
if (mbus == NULL) {
/*
* This should not happen.
* At this point we do not even know the bus number...
*/
printk(KERN_ERR TAG ": Null mon bus in URB, pipe 0x%x\n",
urb->pipe);
return;
}
spin_lock_irqsave(&mbus->lock, flags);
list_for_each (pos, &mbus->r_list) {
r = list_entry(pos, struct mon_reader, r_link);
r->rnf_complete(r->r_data, urb);
}
spin_unlock_irqrestore(&mbus->lock, flags);
}
/* int (*unlink_urb) (struct urb *urb, int status); */
/*
* Stop monitoring.
* Obviously this must be well locked, so no need to play with mb's.
*/
static void mon_stop(struct mon_bus *mbus)
{
struct usb_bus *ubus = mbus->u_bus;
/*
* A stop can be called for a dissolved mon_bus in case of
* a reader staying across an rmmod foo_hcd.
*/
if (ubus != NULL) {
ubus->monitored = 0;
mb();
}
}
/*
* Add a USB bus (usually by a modprobe foo-hcd)
*
* This does not return an error code because the core cannot care less
* if monitoring is not established.
*/
static void mon_bus_add(struct usb_bus *ubus)
{
mon_bus_init(mon_dir, ubus);
}
/*
* Remove a USB bus (either from rmmod foo-hcd or from a hot-remove event).
*/
static void mon_bus_remove(struct usb_bus *ubus)
{
struct mon_bus *mbus = ubus->mon_bus;
down(&mon_lock);
list_del(&mbus->bus_link);
debugfs_remove(mbus->dent_t);
debugfs_remove(mbus->dent_s);
mon_dissolve(mbus, ubus);
kref_put(&mbus->ref, mon_bus_drop);
up(&mon_lock);
}
/*
* Ops
*/
static struct usb_mon_operations mon_ops_0 = {
.urb_submit = mon_submit,
.urb_submit_error = mon_submit_error,
.urb_complete = mon_complete,
.bus_add = mon_bus_add,
.bus_remove = mon_bus_remove,
};
/*
* Tear usb_bus and mon_bus apart.
*/
static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
{
/*
* Never happens, but...
*/
if (ubus->monitored) {
printk(KERN_ERR TAG ": bus %d is dissolved while monitored\n",
ubus->busnum);
ubus->monitored = 0;
mb();
}
ubus->mon_bus = NULL;
mbus->u_bus = NULL;
mb();
// usb_bus_put(ubus);
}
/*
*/
static void mon_bus_drop(struct kref *r)
{
struct mon_bus *mbus = container_of(r, struct mon_bus, ref);
kfree(mbus);
}
/*
* Initialize a bus for us:
* - allocate mon_bus
* - refcount USB bus struct
* - link
*/
static void mon_bus_init(struct dentry *mondir, struct usb_bus *ubus)
{
struct dentry *d;
struct mon_bus *mbus;
enum { NAMESZ = 10 };
char name[NAMESZ];
int rc;
if ((mbus = kmalloc(sizeof(struct mon_bus), GFP_KERNEL)) == NULL)
goto err_alloc;
memset(mbus, 0, sizeof(struct mon_bus));
kref_init(&mbus->ref);
spin_lock_init(&mbus->lock);
INIT_LIST_HEAD(&mbus->r_list);
/*
* This usb_bus_get here is superfluous, because we receive
* a notification if usb_bus is about to be removed.
*/
// usb_bus_get(ubus);
mbus->u_bus = ubus;
ubus->mon_bus = mbus;
rc = snprintf(name, NAMESZ, "%dt", ubus->busnum);
if (rc <= 0 || rc >= NAMESZ)
goto err_print_t;
d = debugfs_create_file(name, 0600, mondir, mbus, &mon_fops_text);
if (d == NULL)
goto err_create_t;
mbus->dent_t = d;
rc = snprintf(name, NAMESZ, "%ds", ubus->busnum);
if (rc <= 0 || rc >= NAMESZ)
goto err_print_s;
d = debugfs_create_file(name, 0600, mondir, mbus, &mon_fops_stat);
if (d == NULL)
goto err_create_s;
mbus->dent_s = d;
down(&mon_lock);
list_add_tail(&mbus->bus_link, &mon_buses);
up(&mon_lock);
return;
err_create_s:
err_print_s:
debugfs_remove(mbus->dent_t);
err_create_t:
err_print_t:
kfree(mbus);
err_alloc:
return;
}
static int __init mon_init(void)
{
struct usb_bus *ubus;
struct dentry *mondir;
mondir = debugfs_create_dir("usbmon", NULL);
if (IS_ERR(mondir)) {
printk(KERN_NOTICE TAG ": debugs is not available\n");
return -ENODEV;
}
if (mondir == NULL) {
printk(KERN_NOTICE TAG ": unable to create usbmon directory\n");
return -ENODEV;
}
mon_dir = mondir;
if (usb_mon_register(&mon_ops_0) != 0) {
printk(KERN_NOTICE TAG ": unable to register with the core\n");
debugfs_remove(mondir);
return -ENODEV;
}
// MOD_INC_USE_COUNT(which_module?);
down(&usb_bus_list_lock);
list_for_each_entry (ubus, &usb_bus_list, bus_list) {
mon_bus_init(mondir, ubus);
}
up(&usb_bus_list_lock);
return 0;
}
static void __exit mon_exit(void)
{
struct mon_bus *mbus;
struct list_head *p;
usb_mon_deregister();
down(&mon_lock);
while (!list_empty(&mon_buses)) {
p = mon_buses.next;
mbus = list_entry(p, struct mon_bus, bus_link);
list_del(p);
debugfs_remove(mbus->dent_t);
debugfs_remove(mbus->dent_s);
/*
* This never happens, because the open/close paths in
* file level maintain module use counters and so rmmod fails
* before reaching here. However, better be safe...
*/
if (mbus->nreaders) {
printk(KERN_ERR TAG
": Outstanding opens (%d) on usb%d, leaking...\n",
mbus->nreaders, mbus->u_bus->busnum);
atomic_set(&mbus->ref.refcount, 2); /* Force leak */
}
mon_dissolve(mbus, mbus->u_bus);
kref_put(&mbus->ref, mon_bus_drop);
}
up(&mon_lock);
debugfs_remove(mon_dir);
}
module_init(mon_init);
module_exit(mon_exit);
MODULE_LICENSE("GPL");
