v4.19.13 snapshot.
diff --git a/drivers/usb/mon/mon_main.c b/drivers/usb/mon/mon_main.c
new file mode 100644
index 0000000..9812d10
--- /dev/null
+++ b/drivers/usb/mon/mon_main.c
@@ -0,0 +1,435 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ *
+ * mon_main.c: Main file, module initiation and exit, registrations, etc.
+ *
+ * Copyright (C) 2005 Pete Zaitcev (zaitcev@redhat.com)
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/usb/hcd.h>
+#include <linux/slab.h>
+#include <linux/notifier.h>
+#include <linux/mutex.h>
+
+#include "usb_mon.h"
+
+
+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 usb_bus *ubus);
+
+DEFINE_MUTEX(mon_lock);
+
+struct mon_bus mon_bus0; /* Pseudo bus meaning "all buses" */
+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 list_head *p;
+
+ spin_lock_irqsave(&mbus->lock, flags);
+ if (mbus->nreaders == 0) {
+ if (mbus == &mon_bus0) {
+ list_for_each (p, &mon_buses) {
+ struct mon_bus *m1;
+ m1 = list_entry(p, struct mon_bus, bus_link);
+ m1->u_bus->monitored = 1;
+ }
+ } else {
+ mbus->u_bus->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_bus_submit(struct mon_bus *mbus, struct urb *urb)
+{
+ unsigned long flags;
+ struct list_head *pos;
+ struct mon_reader *r;
+
+ spin_lock_irqsave(&mbus->lock, flags);
+ mbus->cnt_events++;
+ 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);
+}
+
+static void mon_submit(struct usb_bus *ubus, struct urb *urb)
+{
+ struct mon_bus *mbus;
+
+ mbus = ubus->mon_bus;
+ if (mbus != NULL)
+ mon_bus_submit(mbus, urb);
+ mon_bus_submit(&mon_bus0, urb);
+}
+
+/*
+ */
+static void mon_bus_submit_error(struct mon_bus *mbus, struct urb *urb, int error)
+{
+ unsigned long flags;
+ struct list_head *pos;
+ struct mon_reader *r;
+
+ spin_lock_irqsave(&mbus->lock, flags);
+ mbus->cnt_events++;
+ list_for_each (pos, &mbus->r_list) {
+ r = list_entry(pos, struct mon_reader, r_link);
+ r->rnf_error(r->r_data, urb, error);
+ }
+ spin_unlock_irqrestore(&mbus->lock, flags);
+}
+
+static void mon_submit_error(struct usb_bus *ubus, struct urb *urb, int error)
+{
+ struct mon_bus *mbus;
+
+ mbus = ubus->mon_bus;
+ if (mbus != NULL)
+ mon_bus_submit_error(mbus, urb, error);
+ mon_bus_submit_error(&mon_bus0, urb, error);
+}
+
+/*
+ */
+static void mon_bus_complete(struct mon_bus *mbus, struct urb *urb, int status)
+{
+ unsigned long flags;
+ struct list_head *pos;
+ struct mon_reader *r;
+
+ spin_lock_irqsave(&mbus->lock, flags);
+ mbus->cnt_events++;
+ list_for_each (pos, &mbus->r_list) {
+ r = list_entry(pos, struct mon_reader, r_link);
+ r->rnf_complete(r->r_data, urb, status);
+ }
+ spin_unlock_irqrestore(&mbus->lock, flags);
+}
+
+static void mon_complete(struct usb_bus *ubus, struct urb *urb, int status)
+{
+ struct mon_bus *mbus;
+
+ mbus = ubus->mon_bus;
+ if (mbus != NULL)
+ mon_bus_complete(mbus, urb, status);
+ mon_bus_complete(&mon_bus0, urb, status);
+}
+
+/* int (*unlink_urb) (struct urb *urb, int status); */
+
+/*
+ * Stop monitoring.
+ */
+static void mon_stop(struct mon_bus *mbus)
+{
+ struct usb_bus *ubus;
+ struct list_head *p;
+
+ if (mbus == &mon_bus0) {
+ list_for_each (p, &mon_buses) {
+ mbus = list_entry(p, struct mon_bus, bus_link);
+ /*
+ * We do not change nreaders here, so rely on mon_lock.
+ */
+ if (mbus->nreaders == 0 && (ubus = mbus->u_bus) != NULL)
+ ubus->monitored = 0;
+ }
+ } else {
+ /*
+ * A stop can be called for a dissolved mon_bus in case of
+ * a reader staying across an rmmod foo_hcd, so test ->u_bus.
+ */
+ if (mon_bus0.nreaders == 0 && (ubus = mbus->u_bus) != 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(ubus);
+ mutex_lock(&mon_lock);
+ if (mon_bus0.nreaders != 0)
+ ubus->monitored = 1;
+ mutex_unlock(&mon_lock);
+}
+
+/*
+ * 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;
+
+ mutex_lock(&mon_lock);
+ list_del(&mbus->bus_link);
+ if (mbus->text_inited)
+ mon_text_del(mbus);
+ if (mbus->bin_inited)
+ mon_bin_del(mbus);
+
+ mon_dissolve(mbus, ubus);
+ kref_put(&mbus->ref, mon_bus_drop);
+ mutex_unlock(&mon_lock);
+}
+
+static int mon_notify(struct notifier_block *self, unsigned long action,
+ void *dev)
+{
+ switch (action) {
+ case USB_BUS_ADD:
+ mon_bus_add(dev);
+ break;
+ case USB_BUS_REMOVE:
+ mon_bus_remove(dev);
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block mon_nb = {
+ .notifier_call = mon_notify,
+};
+
+/*
+ * Ops
+ */
+static const struct usb_mon_operations mon_ops_0 = {
+ .urb_submit = mon_submit,
+ .urb_submit_error = mon_submit_error,
+ .urb_complete = mon_complete,
+};
+
+/*
+ * Tear usb_bus and mon_bus apart.
+ */
+static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
+{
+
+ if (ubus->monitored) {
+ ubus->monitored = 0;
+ mb();
+ }
+
+ ubus->mon_bus = NULL;
+ mbus->u_bus = NULL;
+ mb();
+
+ /* We want synchronize_irq() here, but that needs an argument. */
+}
+
+/*
+ */
+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 usb_bus *ubus)
+{
+ struct mon_bus *mbus;
+
+ mbus = kzalloc(sizeof(struct mon_bus), GFP_KERNEL);
+ if (mbus == NULL)
+ goto err_alloc;
+ kref_init(&mbus->ref);
+ spin_lock_init(&mbus->lock);
+ INIT_LIST_HEAD(&mbus->r_list);
+
+ /*
+ * We don't need to take a reference to ubus, because we receive
+ * a notification if the bus is about to be removed.
+ */
+ mbus->u_bus = ubus;
+ ubus->mon_bus = mbus;
+
+ mbus->text_inited = mon_text_add(mbus, ubus);
+ mbus->bin_inited = mon_bin_add(mbus, ubus);
+
+ mutex_lock(&mon_lock);
+ list_add_tail(&mbus->bus_link, &mon_buses);
+ mutex_unlock(&mon_lock);
+ return;
+
+err_alloc:
+ return;
+}
+
+static void mon_bus0_init(void)
+{
+ struct mon_bus *mbus = &mon_bus0;
+
+ kref_init(&mbus->ref);
+ spin_lock_init(&mbus->lock);
+ INIT_LIST_HEAD(&mbus->r_list);
+
+ mbus->text_inited = mon_text_add(mbus, NULL);
+ mbus->bin_inited = mon_bin_add(mbus, NULL);
+}
+
+/*
+ * Search a USB bus by number. Notice that USB bus numbers start from one,
+ * which we may later use to identify "all" with zero.
+ *
+ * This function must be called with mon_lock held.
+ *
+ * This is obviously inefficient and may be revised in the future.
+ */
+struct mon_bus *mon_bus_lookup(unsigned int num)
+{
+ struct list_head *p;
+ struct mon_bus *mbus;
+
+ if (num == 0) {
+ return &mon_bus0;
+ }
+ list_for_each (p, &mon_buses) {
+ mbus = list_entry(p, struct mon_bus, bus_link);
+ if (mbus->u_bus->busnum == num) {
+ return mbus;
+ }
+ }
+ return NULL;
+}
+
+static int __init mon_init(void)
+{
+ struct usb_bus *ubus;
+ int rc, id;
+
+ if ((rc = mon_text_init()) != 0)
+ goto err_text;
+ if ((rc = mon_bin_init()) != 0)
+ goto err_bin;
+
+ mon_bus0_init();
+
+ if (usb_mon_register(&mon_ops_0) != 0) {
+ printk(KERN_NOTICE TAG ": unable to register with the core\n");
+ rc = -ENODEV;
+ goto err_reg;
+ }
+ // MOD_INC_USE_COUNT(which_module?);
+
+ mutex_lock(&usb_bus_idr_lock);
+ idr_for_each_entry(&usb_bus_idr, ubus, id)
+ mon_bus_init(ubus);
+ usb_register_notify(&mon_nb);
+ mutex_unlock(&usb_bus_idr_lock);
+ return 0;
+
+err_reg:
+ mon_bin_exit();
+err_bin:
+ mon_text_exit();
+err_text:
+ return rc;
+}
+
+static void __exit mon_exit(void)
+{
+ struct mon_bus *mbus;
+ struct list_head *p;
+
+ usb_unregister_notify(&mon_nb);
+ usb_mon_deregister();
+
+ mutex_lock(&mon_lock);
+
+ while (!list_empty(&mon_buses)) {
+ p = mon_buses.next;
+ mbus = list_entry(p, struct mon_bus, bus_link);
+ list_del(p);
+
+ if (mbus->text_inited)
+ mon_text_del(mbus);
+ if (mbus->bin_inited)
+ mon_bin_del(mbus);
+
+ /*
+ * 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);
+ kref_get(&mbus->ref); /* Force leak */
+ }
+
+ mon_dissolve(mbus, mbus->u_bus);
+ kref_put(&mbus->ref, mon_bus_drop);
+ }
+
+ mbus = &mon_bus0;
+ if (mbus->text_inited)
+ mon_text_del(mbus);
+ if (mbus->bin_inited)
+ mon_bin_del(mbus);
+
+ mutex_unlock(&mon_lock);
+
+ mon_text_exit();
+ mon_bin_exit();
+}
+
+module_init(mon_init);
+module_exit(mon_exit);
+
+MODULE_LICENSE("GPL");