Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

6 files changed, 936 insertions, 0 deletions

diff --git a/drivers/usb/mon/Kconfig b/drivers/usb/mon/Kconfig
new file mode 100644
index 000000000000..4e6152aa5f19
--- /dev/null
+++ b/drivers/usb/mon/Kconfig
@@ -0,0 +1,22 @@
+#
+# USB Monitor configuration
+#
+
+# In normal life, it makes little sense to have usbmon as a module, and in fact
+# it is harmful, because there is no way to autoload the module.
+# The 'm' option is allowed for hackers who debug the usbmon itself,
+# and for those who have usbcore as a module.
+config USB_MON
+        tristate "USB Monitor"
+        depends on USB
+        default y
+        help
+          If you say Y here, a component which captures the USB traffic
+          between peripheral-specific drivers and HC drivers will be built.
+          The USB_MON is similar in spirit and may be compatible with Dave
+          Harding's USBMon.
+
+          This is somewhat experimental at this time, but it should be safe,
+          as long as you aren't building this as a module and then removing it.
+
+          If unsure, say Y. Do not say M.
diff --git a/drivers/usb/mon/Makefile b/drivers/usb/mon/Makefile
new file mode 100644
index 000000000000..3cff8d444bb1
--- /dev/null
+++ b/drivers/usb/mon/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for USB Core files and filesystem
+#
+
+usbmon-objs     := mon_main.o mon_stat.o mon_text.o
+
+obj-$(CONFIG_USB_MON)   += usbmon.o
diff --git a/drivers/usb/mon/mon_main.c b/drivers/usb/mon/mon_main.c
new file mode 100644
index 000000000000..aa9d00808e4e
--- /dev/null
+++ b/drivers/usb/mon/mon_main.c
@@ -0,0 +1,377 @@
+/*
+ * 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");
diff --git a/drivers/usb/mon/mon_stat.c b/drivers/usb/mon/mon_stat.c
new file mode 100644
index 000000000000..6e4b165d070a
--- /dev/null
+++ b/drivers/usb/mon/mon_stat.c
@@ -0,0 +1,74 @@
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ *
+ * This is the 's' or 'stat' reader which debugs usbmon itself.
+ * Note that this code blows through locks, so make sure that
+ * /dbg/usbmon/0s is well protected from non-root users.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/usb.h>
+#include <asm/uaccess.h>
+
+#include "usb_mon.h"
+
+#define STAT_BUF_SIZE  80
+
+struct snap {
+        int slen;
+        char str[STAT_BUF_SIZE];
+};
+
+static int mon_stat_open(struct inode *inode, struct file *file)
+{
+        struct mon_bus *mbus;
+        struct snap *sp;
+
+        if ((sp = kmalloc(sizeof(struct snap), GFP_KERNEL)) == NULL)
+                return -ENOMEM;
+
+        mbus = inode->u.generic_ip;
+
+        sp->slen = snprintf(sp->str, STAT_BUF_SIZE,
+            "nreaders %d text_lost %u\n",
+            mbus->nreaders, mbus->cnt_text_lost);
+
+        file->private_data = sp;
+        return 0;
+}
+
+static ssize_t mon_stat_read(struct file *file, char __user *buf,
+                                size_t nbytes, loff_t *ppos)
+{
+        struct snap *sp = file->private_data;
+        loff_t pos = *ppos;
+        int cnt;
+
+        if (pos < 0 || pos >= sp->slen)
+                return 0;
+        if (nbytes == 0)
+                return 0;
+        if ((cnt = sp->slen - pos) > nbytes)
+                cnt = nbytes;
+        if (copy_to_user(buf, sp->str + pos, cnt))
+                return -EFAULT;
+        *ppos = pos + cnt;
+        return cnt;
+}
+
+static int mon_stat_release(struct inode *inode, struct file *file)
+{
+        return 0;
+}
+
+struct file_operations mon_fops_stat = {
+        .owner =        THIS_MODULE,
+        .open =         mon_stat_open,
+        .llseek =       no_llseek,
+        .read =         mon_stat_read,
+        /* .write =     mon_stat_write, */
+        /* .poll =              mon_stat_poll, */
+        /* .ioctl =     mon_stat_ioctl, */
+        .release =      mon_stat_release,
+};
diff --git a/drivers/usb/mon/mon_text.c b/drivers/usb/mon/mon_text.c
new file mode 100644
index 000000000000..755a4570477f
--- /dev/null
+++ b/drivers/usb/mon/mon_text.c
@@ -0,0 +1,405 @@
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ *
+ * This is a text format reader.
+ */
+
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/usb.h>
+#include <linux/time.h>
+#include <asm/uaccess.h>
+
+#include "usb_mon.h"
+
+/*
+ * No, we do not want arbitrarily long data strings.
+ * Use the binary interface if you want to capture bulk data!
+ */
+#define DATA_MAX  32
+
+/*
+ * This limit exists to prevent OOMs when the user process stops reading.
+ */
+#define EVENT_MAX  25
+
+#define PRINTF_DFL  120
+
+struct mon_event_text {
+        struct list_head e_link;
+        int type;               /* submit, complete, etc. */
+        unsigned int pipe;      /* Pipe */
+        unsigned long id;       /* From pointer, most of the time */
+        unsigned int tstamp;
+        int length;             /* Depends on type: xfer length or act length */
+        int status;
+        char data_flag;
+        unsigned char data[DATA_MAX];
+};
+
+#define SLAB_NAME_SZ  30
+struct mon_reader_text {
+        kmem_cache_t *e_slab;
+        int nevents;
+        struct list_head e_list;
+        struct mon_reader r;    /* In C, parent class can be placed anywhere */
+
+        wait_queue_head_t wait;
+        int printf_size;
+        char *printf_buf;
+        struct semaphore printf_lock;
+
+        char slab_name[SLAB_NAME_SZ];
+};
+
+static void mon_text_ctor(void *, kmem_cache_t *, unsigned long);
+static void mon_text_dtor(void *, kmem_cache_t *, unsigned long);
+
+/*
+ * mon_text_submit
+ * mon_text_complete
+ *
+ * May be called from an interrupt.
+ *
+ * This is called with the whole mon_bus locked, so no additional lock.
+ */
+
+static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
+    int len, char ev_type)
+{
+        int pipe = urb->pipe;
+        unsigned char *data;
+
+        /*
+         * The check to see if it's safe to poke at data has an enormous
+         * number of corner cases, but it seems that the following is
+         * more or less safe.
+         *
+         * We do not even try to look transfer_buffer, because it can
+         * contain non-NULL garbage in case the upper level promised to
+         * set DMA for the HCD.
+         */
+        if (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
+                return 'D';
+
+        if (len <= 0)
+                return 'L';
+
+        if ((data = urb->transfer_buffer) == NULL)
+                return 'Z';     /* '0' would be not as pretty. */
+
+        /*
+         * Bulk is easy to shortcut reliably. 
+         * XXX Control needs setup packet taken.
+         * XXX Other pipe types need consideration. Currently, we overdo it
+         * and collect garbage for them: better more than less.
+         */
+        if (usb_pipebulk(pipe) || usb_pipecontrol(pipe)) {
+                if (usb_pipein(pipe)) {
+                        if (ev_type == 'S')
+                                return '<';
+                } else {
+                        if (ev_type == 'C')
+                                return '>';
+                }
+        }
+
+        if (len >= DATA_MAX)
+                len = DATA_MAX;
+        memcpy(ep->data, urb->transfer_buffer, len);
+        return 0;
+}
+
+static inline unsigned int mon_get_timestamp(void)
+{
+        struct timeval tval;
+        unsigned int stamp;
+
+        do_gettimeofday(&tval);
+        stamp = tval.tv_sec & 0xFFFF;   /* 2^32 = 4294967296. Limit to 4096s. */
+        stamp = stamp * 1000000 + tval.tv_usec;
+        return stamp;
+}
+
+static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
+    char ev_type)
+{
+        struct mon_event_text *ep;
+        unsigned int stamp;
+
+        stamp = mon_get_timestamp();
+
+        if (rp->nevents >= EVENT_MAX ||
+            (ep = kmem_cache_alloc(rp->e_slab, SLAB_ATOMIC)) == NULL) {
+                rp->r.m_bus->cnt_text_lost++;
+                return;
+        }
+
+        ep->type = ev_type;
+        ep->pipe = urb->pipe;
+        ep->id = (unsigned long) urb;
+        ep->tstamp = stamp;
+        ep->length = (ev_type == 'S') ?
+            urb->transfer_buffer_length : urb->actual_length;
+        /* Collecting status makes debugging sense for submits, too */
+        ep->status = urb->status;
+
+        ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type);
+
+        rp->nevents++;
+        list_add_tail(&ep->e_link, &rp->e_list);
+        wake_up(&rp->wait);
+}
+
+static void mon_text_submit(void *data, struct urb *urb)
+{
+        struct mon_reader_text *rp = data;
+        mon_text_event(rp, urb, 'S');
+}
+
+static void mon_text_complete(void *data, struct urb *urb)
+{
+        struct mon_reader_text *rp = data;
+        mon_text_event(rp, urb, 'C');
+}
+
+/*
+ * Fetch next event from the circular buffer.
+ */
+static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
+    struct mon_bus *mbus)
+{
+        struct list_head *p;
+        unsigned long flags;
+
+        spin_lock_irqsave(&mbus->lock, flags);
+        if (list_empty(&rp->e_list)) {
+                spin_unlock_irqrestore(&mbus->lock, flags);
+                return NULL;
+        }
+        p = rp->e_list.next;
+        list_del(p);
+        --rp->nevents;
+        spin_unlock_irqrestore(&mbus->lock, flags);
+        return list_entry(p, struct mon_event_text, e_link);
+}
+
+/*
+ */
+static int mon_text_open(struct inode *inode, struct file *file)
+{
+        struct mon_bus *mbus;
+        struct usb_bus *ubus;
+        struct mon_reader_text *rp;
+        int rc;
+
+        down(&mon_lock);
+        mbus = inode->u.generic_ip;
+        ubus = mbus->u_bus;
+
+        rp = kmalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
+        if (rp == NULL) {
+                rc = -ENOMEM;
+                goto err_alloc;
+        }
+        memset(rp, 0, sizeof(struct mon_reader_text));
+        INIT_LIST_HEAD(&rp->e_list);
+        init_waitqueue_head(&rp->wait);
+        init_MUTEX(&rp->printf_lock);
+
+        rp->printf_size = PRINTF_DFL;
+        rp->printf_buf = kmalloc(rp->printf_size, GFP_KERNEL);
+        if (rp->printf_buf == NULL) {
+                rc = -ENOMEM;
+                goto err_alloc_pr;
+        }
+
+        rp->r.m_bus = mbus;
+        rp->r.r_data = rp;
+        rp->r.rnf_submit = mon_text_submit;
+        rp->r.rnf_complete = mon_text_complete;
+
+        snprintf(rp->slab_name, SLAB_NAME_SZ, "mon%dt_%lx", ubus->busnum,
+            (long)rp);
+        rp->e_slab = kmem_cache_create(rp->slab_name,
+            sizeof(struct mon_event_text), sizeof(long), 0,
+            mon_text_ctor, mon_text_dtor);
+        if (rp->e_slab == NULL) {
+                rc = -ENOMEM;
+                goto err_slab;
+        }
+
+        mon_reader_add(mbus, &rp->r);
+
+        file->private_data = rp;
+        up(&mon_lock);
+        return 0;
+
+// err_busy:
+//      kmem_cache_destroy(rp->e_slab);
+err_slab:
+        kfree(rp->printf_buf);
+err_alloc_pr:
+        kfree(rp);
+err_alloc:
+        up(&mon_lock);
+        return rc;
+}
+
+/*
+ * For simplicity, we read one record in one system call and throw out
+ * what does not fit. This means that the following does not work:
+ *   dd if=/dbg/usbmon/0t bs=10
+ * Also, we do not allow seeks and do not bother advancing the offset.
+ */
+static ssize_t mon_text_read(struct file *file, char __user *buf,
+                                size_t nbytes, loff_t *ppos)
+{
+        struct mon_reader_text *rp = file->private_data;
+        struct mon_bus *mbus = rp->r.m_bus;
+        DECLARE_WAITQUEUE(waita, current);
+        struct mon_event_text *ep;
+        int cnt, limit;
+        char *pbuf;
+        char udir, utype;
+        int data_len, i;
+
+        add_wait_queue(&rp->wait, &waita);
+        set_current_state(TASK_INTERRUPTIBLE);
+        while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
+                if (file->f_flags & O_NONBLOCK) {
+                        set_current_state(TASK_RUNNING);
+                        remove_wait_queue(&rp->wait, &waita);
+                        return -EWOULDBLOCK;    /* Same as EAGAIN in Linux */
+                }
+                /*
+                 * We do not count nwaiters, because ->release is supposed
+                 * to be called when all openers are gone only.
+                 */
+                schedule();
+                if (signal_pending(current)) {
+                        remove_wait_queue(&rp->wait, &waita);
+                        return -EINTR;
+                }
+                set_current_state(TASK_INTERRUPTIBLE);
+        }
+        set_current_state(TASK_RUNNING);
+        remove_wait_queue(&rp->wait, &waita);
+
+        down(&rp->printf_lock);
+        cnt = 0;
+        pbuf = rp->printf_buf;
+        limit = rp->printf_size;
+
+        udir = usb_pipein(ep->pipe) ? 'i' : 'o';
+        switch (usb_pipetype(ep->pipe)) {
+        case PIPE_ISOCHRONOUS:  utype = 'Z'; break;
+        case PIPE_INTERRUPT:    utype = 'I'; break;
+        case PIPE_CONTROL:      utype = 'C'; break;
+        default: /* PIPE_BULK */  utype = 'B';
+        }
+        cnt += snprintf(pbuf + cnt, limit - cnt,
+            "%lx %u %c %c%c:%03u:%02u %d %d",
+            ep->id, ep->tstamp, ep->type,
+            utype, udir, usb_pipedevice(ep->pipe), usb_pipeendpoint(ep->pipe),
+            ep->status, ep->length);
+
+        if ((data_len = ep->length) > 0) {
+                if (ep->data_flag == 0) {
+                        cnt += snprintf(pbuf + cnt, limit - cnt, " =");
+                        if (data_len >= DATA_MAX)
+                                data_len = DATA_MAX;
+                        for (i = 0; i < data_len; i++) {
+                                if (i % 4 == 0) {
+                                        cnt += snprintf(pbuf + cnt, limit - cnt,
+                                            " ");
+                                }
+                                cnt += snprintf(pbuf + cnt, limit - cnt,
+                                    "%02x", ep->data[i]);
+                        }
+                        cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
+                } else {
+                        cnt += snprintf(pbuf + cnt, limit - cnt,
+                            " %c\n", ep->data_flag);
+                }
+        } else {
+                cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
+        }
+
+        if (copy_to_user(buf, rp->printf_buf, cnt))
+                cnt = -EFAULT;
+        up(&rp->printf_lock);
+        kmem_cache_free(rp->e_slab, ep);
+        return cnt;
+}
+
+static int mon_text_release(struct inode *inode, struct file *file)
+{
+        struct mon_reader_text *rp = file->private_data;
+        struct mon_bus *mbus;
+        /* unsigned long flags; */
+        struct list_head *p;
+        struct mon_event_text *ep;
+
+        down(&mon_lock);
+        mbus = inode->u.generic_ip;
+
+        if (mbus->nreaders <= 0) {
+                printk(KERN_ERR TAG ": consistency error on close\n");
+                up(&mon_lock);
+                return 0;
+        }
+        mon_reader_del(mbus, &rp->r);
+
+        /*
+         * In theory, e_list is protected by mbus->lock. However,
+         * after mon_reader_del has finished, the following is the case:
+         *  - we are not on reader list anymore, so new events won't be added;
+         *  - whole mbus may be dropped if it was orphaned.
+         * So, we better not touch mbus.
+         */
+        /* spin_lock_irqsave(&mbus->lock, flags); */
+        while (!list_empty(&rp->e_list)) {
+                p = rp->e_list.next;
+                ep = list_entry(p, struct mon_event_text, e_link);
+                list_del(p);
+                --rp->nevents;
+                kmem_cache_free(rp->e_slab, ep);
+        }
+        /* spin_unlock_irqrestore(&mbus->lock, flags); */
+
+        kmem_cache_destroy(rp->e_slab);
+        kfree(rp->printf_buf);
+        kfree(rp);
+
+        up(&mon_lock);
+        return 0;
+}
+
+struct file_operations mon_fops_text = {
+        .owner =        THIS_MODULE,
+        .open =         mon_text_open,
+        .llseek =       no_llseek,
+        .read =         mon_text_read,
+        /* .write =     mon_text_write, */
+        /* .poll =              mon_text_poll, */
+        /* .ioctl =     mon_text_ioctl, */
+        .release =      mon_text_release,
+};
+
+/*
+ * Slab interface: constructor.
+ */
+static void mon_text_ctor(void *mem, kmem_cache_t *slab, unsigned long sflags)
+{
+        /*
+         * Nothing to initialize. No, really!
+         * So, we fill it with garbage to emulate a reused object.
+         */
+        memset(mem, 0xe5, sizeof(struct mon_event_text));
+}
+
+static void mon_text_dtor(void *mem, kmem_cache_t *slab, unsigned long sflags)
+{
+        ;
+}
diff --git a/drivers/usb/mon/usb_mon.h b/drivers/usb/mon/usb_mon.h
new file mode 100644
index 000000000000..ed35c18a5c44
--- /dev/null
+++ b/drivers/usb/mon/usb_mon.h
@@ -0,0 +1,51 @@
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ */
+
+#ifndef __USB_MON_H
+#define __USB_MON_H
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/kref.h>
+/* #include <linux/usb.h> */    /* We use struct pointers only in this header */
+
+#define TAG "usbmon"
+
+struct mon_bus {
+        struct list_head bus_link;
+        spinlock_t lock;
+        struct dentry *dent_s;          /* Debugging file */
+        struct dentry *dent_t;          /* Text interface file */
+        struct usb_bus *u_bus;
+
+        /* Ref */
+        int nreaders;                   /* Under mon_lock AND mbus->lock */
+        struct list_head r_list;        /* Chain of readers (usually one) */
+        struct kref ref;                /* Under mon_lock */
+
+        /* Stats */
+        unsigned int cnt_text_lost;
+};
+
+/*
+ * An instance of a process which opened a file (but can fork later)
+ */
+struct mon_reader {
+        struct list_head r_link;
+        struct mon_bus *m_bus;
+        void *r_data;           /* Use container_of instead? */
+
+        void (*rnf_submit)(void *data, struct urb *urb);
+        void (*rnf_complete)(void *data, struct urb *urb);
+};
+
+void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r);
+void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r);
+
+extern struct semaphore mon_lock;
+
+extern struct file_operations mon_fops_text;
+extern struct file_operations mon_fops_stat;
+
+#endif /* __USB_MON_H */