Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

7 files changed, 2763 insertions, 0 deletions

diff --git a/drivers/usb/mon/Kconfig b/drivers/usb/mon/Kconfig
new file mode 100644
index 000000000..ffc7cd422
--- /dev/null
+++ b/drivers/usb/mon/Kconfig
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# USB Monitor configuration
+#
+
+config USB_MON
+	tristate "USB Monitor"
+	help
+	  If you select this option, a component which captures the USB traffic
+	  between peripheral-specific drivers and HC drivers will be built.
+	  For more information, see <file:Documentation/usb/usbmon.rst>.
+
+	  If unsure, say Y, if allowed, otherwise M.
diff --git a/drivers/usb/mon/Makefile b/drivers/usb/mon/Makefile
new file mode 100644
index 000000000..09f43e896
--- /dev/null
+++ b/drivers/usb/mon/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for USB monitor
+#
+
+usbmon-y := mon_main.o mon_stat.o mon_text.o mon_bin.o
+
+obj-$(CONFIG_USB_MON)	+= usbmon.o
diff --git a/drivers/usb/mon/mon_bin.c b/drivers/usb/mon/mon_bin.c
new file mode 100644
index 000000000..687f6a898
--- /dev/null
+++ b/drivers/usb/mon/mon_bin.c
@@ -0,0 +1,1420 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ *
+ * This is a binary format reader.
+ *
+ * Copyright (C) 2006 Paolo Abeni (paolo.abeni@email.it)
+ * Copyright (C) 2006,2007 Pete Zaitcev (zaitcev@redhat.com)
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched/signal.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/export.h>
+#include <linux/usb.h>
+#include <linux/poll.h>
+#include <linux/compat.h>
+#include <linux/mm.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+#include <linux/time64.h>
+
+#include <linux/uaccess.h>
+
+#include "usb_mon.h"
+
+/*
+ * Defined by USB 2.0 clause 9.3, table 9.2.
+ */
+#define SETUP_LEN  8
+
+/* ioctl macros */
+#define MON_IOC_MAGIC 0x92
+
+#define MON_IOCQ_URB_LEN _IO(MON_IOC_MAGIC, 1)
+/* #2 used to be MON_IOCX_URB, removed before it got into Linus tree */
+#define MON_IOCG_STATS _IOR(MON_IOC_MAGIC, 3, struct mon_bin_stats)
+#define MON_IOCT_RING_SIZE _IO(MON_IOC_MAGIC, 4)
+#define MON_IOCQ_RING_SIZE _IO(MON_IOC_MAGIC, 5)
+#define MON_IOCX_GET   _IOW(MON_IOC_MAGIC, 6, struct mon_bin_get)
+#define MON_IOCX_MFETCH _IOWR(MON_IOC_MAGIC, 7, struct mon_bin_mfetch)
+#define MON_IOCH_MFLUSH _IO(MON_IOC_MAGIC, 8)
+/* #9 was MON_IOCT_SETAPI */
+#define MON_IOCX_GETX   _IOW(MON_IOC_MAGIC, 10, struct mon_bin_get)
+
+#ifdef CONFIG_COMPAT
+#define MON_IOCX_GET32 _IOW(MON_IOC_MAGIC, 6, struct mon_bin_get32)
+#define MON_IOCX_MFETCH32 _IOWR(MON_IOC_MAGIC, 7, struct mon_bin_mfetch32)
+#define MON_IOCX_GETX32   _IOW(MON_IOC_MAGIC, 10, struct mon_bin_get32)
+#endif
+
+/*
+ * Some architectures have enormous basic pages (16KB for ia64, 64KB for ppc).
+ * But it's all right. Just use a simple way to make sure the chunk is never
+ * smaller than a page.
+ *
+ * N.B. An application does not know our chunk size.
+ *
+ * Woops, get_zeroed_page() returns a single page. I guess we're stuck with
+ * page-sized chunks for the time being.
+ */
+#define CHUNK_SIZE   PAGE_SIZE
+#define CHUNK_ALIGN(x)   (((x)+CHUNK_SIZE-1) & ~(CHUNK_SIZE-1))
+
+/*
+ * The magic limit was calculated so that it allows the monitoring
+ * application to pick data once in two ticks. This way, another application,
+ * which presumably drives the bus, gets to hog CPU, yet we collect our data.
+ *
+ * Originally, for a 480 Mbit/s bus this required a buffer of about 1 MB. For
+ * modern 20 Gbps buses, this value increases to over 50 MB. The maximum
+ * buffer size is set to 64 MiB to accommodate this.
+ *
+ * This is still too much for most cases, where we just snoop a few
+ * descriptor fetches for enumeration. So, the default is a "reasonable"
+ * amount for typical, low-throughput use cases.
+ *
+ * XXX What about multi-megabyte URBs which take minutes to transfer?
+ */
+#define BUFF_MAX  CHUNK_ALIGN(64*1024*1024)
+#define BUFF_DFL      CHUNK_ALIGN(300*1024)
+#define BUFF_MIN        CHUNK_ALIGN(8*1024)
+
+/*
+ * The per-event API header (2 per URB).
+ *
+ * This structure is seen in userland as defined by the documentation.
+ */
+struct mon_bin_hdr {
+	u64 id;			/* URB ID - from submission to callback */
+	unsigned char type;	/* Same as in text API; extensible. */
+	unsigned char xfer_type;	/* ISO, Intr, Control, Bulk */
+	unsigned char epnum;	/* Endpoint number and transfer direction */
+	unsigned char devnum;	/* Device address */
+	unsigned short busnum;	/* Bus number */
+	char flag_setup;
+	char flag_data;
+	s64 ts_sec;		/* ktime_get_real_ts64 */
+	s32 ts_usec;		/* ktime_get_real_ts64 */
+	int status;
+	unsigned int len_urb;	/* Length of data (submitted or actual) */
+	unsigned int len_cap;	/* Delivered length */
+	union {
+		unsigned char setup[SETUP_LEN];	/* Only for Control S-type */
+		struct iso_rec {
+			int error_count;
+			int numdesc;
+		} iso;
+	} s;
+	int interval;
+	int start_frame;
+	unsigned int xfer_flags;
+	unsigned int ndesc;	/* Actual number of ISO descriptors */
+};
+
+/*
+ * ISO vector, packed into the head of data stream.
+ * This has to take 16 bytes to make sure that the end of buffer
+ * wrap is not happening in the middle of a descriptor.
+ */
+struct mon_bin_isodesc {
+	int          iso_status;
+	unsigned int iso_off;
+	unsigned int iso_len;
+	u32 _pad;
+};
+
+/* per file statistic */
+struct mon_bin_stats {
+	u32 queued;
+	u32 dropped;
+};
+
+struct mon_bin_get {
+	struct mon_bin_hdr __user *hdr;	/* Can be 48 bytes or 64. */
+	void __user *data;
+	size_t alloc;		/* Length of data (can be zero) */
+};
+
+struct mon_bin_mfetch {
+	u32 __user *offvec;	/* Vector of events fetched */
+	u32 nfetch;		/* Number of events to fetch (out: fetched) */
+	u32 nflush;		/* Number of events to flush */
+};
+
+#ifdef CONFIG_COMPAT
+struct mon_bin_get32 {
+	u32 hdr32;
+	u32 data32;
+	u32 alloc32;
+};
+
+struct mon_bin_mfetch32 {
+        u32 offvec32;
+        u32 nfetch32;
+        u32 nflush32;
+};
+#endif
+
+/* Having these two values same prevents wrapping of the mon_bin_hdr */
+#define PKT_ALIGN   64
+#define PKT_SIZE    64
+
+#define PKT_SZ_API0 48	/* API 0 (2.6.20) size */
+#define PKT_SZ_API1 64	/* API 1 size: extra fields */
+
+#define ISODESC_MAX   128	/* Same number as usbfs allows, 2048 bytes. */
+
+/* max number of USB bus supported */
+#define MON_BIN_MAX_MINOR 128
+
+/*
+ * The buffer: map of used pages.
+ */
+struct mon_pgmap {
+	struct page *pg;
+	unsigned char *ptr;	/* XXX just use page_to_virt everywhere? */
+};
+
+/*
+ * This gets associated with an open file struct.
+ */
+struct mon_reader_bin {
+	/* The buffer: one per open. */
+	spinlock_t b_lock;		/* Protect b_cnt, b_in */
+	unsigned int b_size;		/* Current size of the buffer - bytes */
+	unsigned int b_cnt;		/* Bytes used */
+	unsigned int b_in, b_out;	/* Offsets into buffer - bytes */
+	unsigned int b_read;		/* Amount of read data in curr. pkt. */
+	struct mon_pgmap *b_vec;	/* The map array */
+	wait_queue_head_t b_wait;	/* Wait for data here */
+
+	struct mutex fetch_lock;	/* Protect b_read, b_out */
+	int mmap_active;
+
+	/* A list of these is needed for "bus 0". Some time later. */
+	struct mon_reader r;
+
+	/* Stats */
+	unsigned int cnt_lost;
+};
+
+static inline struct mon_bin_hdr *MON_OFF2HDR(const struct mon_reader_bin *rp,
+    unsigned int offset)
+{
+	return (struct mon_bin_hdr *)
+	    (rp->b_vec[offset / CHUNK_SIZE].ptr + offset % CHUNK_SIZE);
+}
+
+#define MON_RING_EMPTY(rp)	((rp)->b_cnt == 0)
+
+static unsigned char xfer_to_pipe[4] = {
+	PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT
+};
+
+static const struct class mon_bin_class = {
+	.name = "usbmon",
+};
+
+static dev_t mon_bin_dev0;
+static struct cdev mon_bin_cdev;
+
+static void mon_buff_area_fill(const struct mon_reader_bin *rp,
+    unsigned int offset, unsigned int size);
+static int mon_bin_wait_event(struct file *file, struct mon_reader_bin *rp);
+static int mon_alloc_buff(struct mon_pgmap *map, int npages);
+static void mon_free_buff(struct mon_pgmap *map, int npages);
+
+/*
+ * This is a "chunked memcpy". It does not manipulate any counters.
+ */
+static unsigned int mon_copy_to_buff(const struct mon_reader_bin *this,
+    unsigned int off, const unsigned char *from, unsigned int length)
+{
+	unsigned int step_len;
+	unsigned char *buf;
+	unsigned int in_page;
+
+	while (length) {
+		/*
+		 * Determine step_len.
+		 */
+		step_len = length;
+		in_page = CHUNK_SIZE - (off & (CHUNK_SIZE-1));
+		if (in_page < step_len)
+			step_len = in_page;
+
+		/*
+		 * Copy data and advance pointers.
+		 */
+		buf = this->b_vec[off / CHUNK_SIZE].ptr + off % CHUNK_SIZE;
+		memcpy(buf, from, step_len);
+		if ((off += step_len) >= this->b_size) off = 0;
+		from += step_len;
+		length -= step_len;
+	}
+	return off;
+}
+
+/*
+ * This is a little worse than the above because it's "chunked copy_to_user".
+ * The return value is an error code, not an offset.
+ */
+static int copy_from_buf(const struct mon_reader_bin *this, unsigned int off,
+    char __user *to, int length)
+{
+	unsigned int step_len;
+	unsigned char *buf;
+	unsigned int in_page;
+
+	while (length) {
+		/*
+		 * Determine step_len.
+		 */
+		step_len = length;
+		in_page = CHUNK_SIZE - (off & (CHUNK_SIZE-1));
+		if (in_page < step_len)
+			step_len = in_page;
+
+		/*
+		 * Copy data and advance pointers.
+		 */
+		buf = this->b_vec[off / CHUNK_SIZE].ptr + off % CHUNK_SIZE;
+		if (copy_to_user(to, buf, step_len))
+			return -EINVAL;
+		if ((off += step_len) >= this->b_size) off = 0;
+		to += step_len;
+		length -= step_len;
+	}
+	return 0;
+}
+
+/*
+ * Allocate an (aligned) area in the buffer.
+ * This is called under b_lock.
+ * Returns ~0 on failure.
+ */
+static unsigned int mon_buff_area_alloc(struct mon_reader_bin *rp,
+    unsigned int size)
+{
+	unsigned int offset;
+
+	size = (size + PKT_ALIGN-1) & ~(PKT_ALIGN-1);
+	if (rp->b_cnt + size > rp->b_size)
+		return ~0;
+	offset = rp->b_in;
+	rp->b_cnt += size;
+	if ((rp->b_in += size) >= rp->b_size)
+		rp->b_in -= rp->b_size;
+	return offset;
+}
+
+/*
+ * This is the same thing as mon_buff_area_alloc, only it does not allow
+ * buffers to wrap. This is needed by applications which pass references
+ * into mmap-ed buffers up their stacks (libpcap can do that).
+ *
+ * Currently, we always have the header stuck with the data, although
+ * it is not strictly speaking necessary.
+ *
+ * When a buffer would wrap, we place a filler packet to mark the space.
+ */
+static unsigned int mon_buff_area_alloc_contiguous(struct mon_reader_bin *rp,
+    unsigned int size)
+{
+	unsigned int offset;
+	unsigned int fill_size;
+
+	size = (size + PKT_ALIGN-1) & ~(PKT_ALIGN-1);
+	if (rp->b_cnt + size > rp->b_size)
+		return ~0;
+	if (rp->b_in + size > rp->b_size) {
+		/*
+		 * This would wrap. Find if we still have space after
+		 * skipping to the end of the buffer. If we do, place
+		 * a filler packet and allocate a new packet.
+		 */
+		fill_size = rp->b_size - rp->b_in;
+		if (rp->b_cnt + size + fill_size > rp->b_size)
+			return ~0;
+		mon_buff_area_fill(rp, rp->b_in, fill_size);
+
+		offset = 0;
+		rp->b_in = size;
+		rp->b_cnt += size + fill_size;
+	} else if (rp->b_in + size == rp->b_size) {
+		offset = rp->b_in;
+		rp->b_in = 0;
+		rp->b_cnt += size;
+	} else {
+		offset = rp->b_in;
+		rp->b_in += size;
+		rp->b_cnt += size;
+	}
+	return offset;
+}
+
+/*
+ * Return a few (kilo-)bytes to the head of the buffer.
+ * This is used if a data fetch fails.
+ */
+static void mon_buff_area_shrink(struct mon_reader_bin *rp, unsigned int size)
+{
+
+	/* size &= ~(PKT_ALIGN-1);  -- we're called with aligned size */
+	rp->b_cnt -= size;
+	if (rp->b_in < size)
+		rp->b_in += rp->b_size;
+	rp->b_in -= size;
+}
+
+/*
+ * This has to be called under both b_lock and fetch_lock, because
+ * it accesses both b_cnt and b_out.
+ */
+static void mon_buff_area_free(struct mon_reader_bin *rp, unsigned int size)
+{
+
+	size = (size + PKT_ALIGN-1) & ~(PKT_ALIGN-1);
+	rp->b_cnt -= size;
+	if ((rp->b_out += size) >= rp->b_size)
+		rp->b_out -= rp->b_size;
+}
+
+static void mon_buff_area_fill(const struct mon_reader_bin *rp,
+    unsigned int offset, unsigned int size)
+{
+	struct mon_bin_hdr *ep;
+
+	ep = MON_OFF2HDR(rp, offset);
+	memset(ep, 0, PKT_SIZE);
+	ep->type = '@';
+	ep->len_cap = size - PKT_SIZE;
+}
+
+static inline char mon_bin_get_setup(unsigned char *setupb,
+    const struct urb *urb, char ev_type)
+{
+
+	if (urb->setup_packet == NULL)
+		return 'Z';
+	memcpy(setupb, urb->setup_packet, SETUP_LEN);
+	return 0;
+}
+
+static unsigned int mon_bin_get_data(const struct mon_reader_bin *rp,
+    unsigned int offset, struct urb *urb, unsigned int length,
+    char *flag)
+{
+	int i;
+	struct scatterlist *sg;
+	unsigned int this_len;
+
+	*flag = 0;
+	if (urb->num_sgs == 0) {
+		if (urb->transfer_buffer == NULL) {
+			*flag = 'Z';
+			return length;
+		}
+		mon_copy_to_buff(rp, offset, urb->transfer_buffer, length);
+		length = 0;
+
+	} else {
+		/* If IOMMU coalescing occurred, we cannot trust sg_page */
+		if (urb->transfer_flags & URB_DMA_SG_COMBINED) {
+			*flag = 'D';
+			return length;
+		}
+
+		/* Copy up to the first non-addressable segment */
+		for_each_sg(urb->sg, sg, urb->num_sgs, i) {
+			if (length == 0 || PageHighMem(sg_page(sg)))
+				break;
+			this_len = min_t(unsigned int, sg->length, length);
+			offset = mon_copy_to_buff(rp, offset, sg_virt(sg),
+					this_len);
+			length -= this_len;
+		}
+		if (i == 0)
+			*flag = 'D';
+	}
+
+	return length;
+}
+
+/*
+ * This is the look-ahead pass in case of 'C Zi', when actual_length cannot
+ * be used to determine the length of the whole contiguous buffer.
+ */
+static unsigned int mon_bin_collate_isodesc(const struct mon_reader_bin *rp,
+    struct urb *urb, unsigned int ndesc)
+{
+	struct usb_iso_packet_descriptor *fp;
+	unsigned int length;
+
+	length = 0;
+	fp = urb->iso_frame_desc;
+	while (ndesc-- != 0) {
+		if (fp->actual_length != 0) {
+			if (fp->offset + fp->actual_length > length)
+				length = fp->offset + fp->actual_length;
+		}
+		fp++;
+	}
+	return length;
+}
+
+static void mon_bin_get_isodesc(const struct mon_reader_bin *rp,
+    unsigned int offset, struct urb *urb, char ev_type, unsigned int ndesc)
+{
+	struct mon_bin_isodesc *dp;
+	struct usb_iso_packet_descriptor *fp;
+
+	fp = urb->iso_frame_desc;
+	while (ndesc-- != 0) {
+		dp = (struct mon_bin_isodesc *)
+		    (rp->b_vec[offset / CHUNK_SIZE].ptr + offset % CHUNK_SIZE);
+		dp->iso_status = fp->status;
+		dp->iso_off = fp->offset;
+		dp->iso_len = (ev_type == 'S') ? fp->length : fp->actual_length;
+		dp->_pad = 0;
+		if ((offset += sizeof(struct mon_bin_isodesc)) >= rp->b_size)
+			offset = 0;
+		fp++;
+	}
+}
+
+static void mon_bin_event(struct mon_reader_bin *rp, struct urb *urb,
+    char ev_type, int status)
+{
+	const struct usb_endpoint_descriptor *epd = &urb->ep->desc;
+	struct timespec64 ts;
+	unsigned long flags;
+	unsigned int urb_length;
+	unsigned int offset;
+	unsigned int length;
+	unsigned int delta;
+	unsigned int ndesc, lendesc;
+	unsigned char dir;
+	struct mon_bin_hdr *ep;
+	char data_tag = 0;
+
+	ktime_get_real_ts64(&ts);
+
+	spin_lock_irqsave(&rp->b_lock, flags);
+
+	/*
+	 * Find the maximum allowable length, then allocate space.
+	 */
+	urb_length = (ev_type == 'S') ?
+	    urb->transfer_buffer_length : urb->actual_length;
+	length = urb_length;
+
+	if (usb_endpoint_xfer_isoc(epd)) {
+		if (urb->number_of_packets < 0) {
+			ndesc = 0;
+		} else if (urb->number_of_packets >= ISODESC_MAX) {
+			ndesc = ISODESC_MAX;
+		} else {
+			ndesc = urb->number_of_packets;
+		}
+		if (ev_type == 'C' && usb_urb_dir_in(urb))
+			length = mon_bin_collate_isodesc(rp, urb, ndesc);
+	} else {
+		ndesc = 0;
+	}
+	lendesc = ndesc*sizeof(struct mon_bin_isodesc);
+
+	/* not an issue unless there's a subtle bug in a HCD somewhere */
+	if (length >= urb->transfer_buffer_length)
+		length = urb->transfer_buffer_length;
+
+	if (length >= rp->b_size/5)
+		length = rp->b_size/5;
+
+	if (usb_urb_dir_in(urb)) {
+		if (ev_type == 'S') {
+			length = 0;
+			data_tag = '<';
+		}
+		/* Cannot rely on endpoint number in case of control ep.0 */
+		dir = USB_DIR_IN;
+	} else {
+		if (ev_type == 'C') {
+			length = 0;
+			data_tag = '>';
+		}
+		dir = 0;
+	}
+
+	if (rp->mmap_active) {
+		offset = mon_buff_area_alloc_contiguous(rp,
+						 length + PKT_SIZE + lendesc);
+	} else {
+		offset = mon_buff_area_alloc(rp, length + PKT_SIZE + lendesc);
+	}
+	if (offset == ~0) {
+		rp->cnt_lost++;
+		spin_unlock_irqrestore(&rp->b_lock, flags);
+		return;
+	}
+
+	ep = MON_OFF2HDR(rp, offset);
+	if ((offset += PKT_SIZE) >= rp->b_size) offset = 0;
+
+	/*
+	 * Fill the allocated area.
+	 */
+	memset(ep, 0, PKT_SIZE);
+	ep->type = ev_type;
+	ep->xfer_type = xfer_to_pipe[usb_endpoint_type(epd)];
+	ep->epnum = dir | usb_endpoint_num(epd);
+	ep->devnum = urb->dev->devnum;
+	ep->busnum = urb->dev->bus->busnum;
+	ep->id = (unsigned long) urb;
+	ep->ts_sec = ts.tv_sec;
+	ep->ts_usec = ts.tv_nsec / NSEC_PER_USEC;
+	ep->status = status;
+	ep->len_urb = urb_length;
+	ep->len_cap = length + lendesc;
+	ep->xfer_flags = urb->transfer_flags;
+
+	if (usb_endpoint_xfer_int(epd)) {
+		ep->interval = urb->interval;
+	} else if (usb_endpoint_xfer_isoc(epd)) {
+		ep->interval = urb->interval;
+		ep->start_frame = urb->start_frame;
+		ep->s.iso.error_count = urb->error_count;
+		ep->s.iso.numdesc = urb->number_of_packets;
+	}
+
+	if (usb_endpoint_xfer_control(epd) && ev_type == 'S') {
+		ep->flag_setup = mon_bin_get_setup(ep->s.setup, urb, ev_type);
+	} else {
+		ep->flag_setup = '-';
+	}
+
+	if (ndesc != 0) {
+		ep->ndesc = ndesc;
+		mon_bin_get_isodesc(rp, offset, urb, ev_type, ndesc);
+		if ((offset += lendesc) >= rp->b_size)
+			offset -= rp->b_size;
+	}
+
+	if (length != 0) {
+		length = mon_bin_get_data(rp, offset, urb, length,
+				&ep->flag_data);
+		if (length > 0) {
+			delta = (ep->len_cap + PKT_ALIGN-1) & ~(PKT_ALIGN-1);
+			ep->len_cap -= length;
+			delta -= (ep->len_cap + PKT_ALIGN-1) & ~(PKT_ALIGN-1);
+			mon_buff_area_shrink(rp, delta);
+		}
+	} else {
+		ep->flag_data = data_tag;
+	}
+
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+
+	wake_up(&rp->b_wait);
+}
+
+static void mon_bin_submit(void *data, struct urb *urb)
+{
+	struct mon_reader_bin *rp = data;
+	mon_bin_event(rp, urb, 'S', -EINPROGRESS);
+}
+
+static void mon_bin_complete(void *data, struct urb *urb, int status)
+{
+	struct mon_reader_bin *rp = data;
+	mon_bin_event(rp, urb, 'C', status);
+}
+
+static void mon_bin_error(void *data, struct urb *urb, int error)
+{
+	struct mon_reader_bin *rp = data;
+	struct timespec64 ts;
+	unsigned long flags;
+	unsigned int offset;
+	struct mon_bin_hdr *ep;
+
+	ktime_get_real_ts64(&ts);
+
+	spin_lock_irqsave(&rp->b_lock, flags);
+
+	offset = mon_buff_area_alloc(rp, PKT_SIZE);
+	if (offset == ~0) {
+		/* Not incrementing cnt_lost. Just because. */
+		spin_unlock_irqrestore(&rp->b_lock, flags);
+		return;
+	}
+
+	ep = MON_OFF2HDR(rp, offset);
+
+	memset(ep, 0, PKT_SIZE);
+	ep->type = 'E';
+	ep->xfer_type = xfer_to_pipe[usb_endpoint_type(&urb->ep->desc)];
+	ep->epnum = usb_urb_dir_in(urb) ? USB_DIR_IN : 0;
+	ep->epnum |= usb_endpoint_num(&urb->ep->desc);
+	ep->devnum = urb->dev->devnum;
+	ep->busnum = urb->dev->bus->busnum;
+	ep->id = (unsigned long) urb;
+	ep->ts_sec = ts.tv_sec;
+	ep->ts_usec = ts.tv_nsec / NSEC_PER_USEC;
+	ep->status = error;
+
+	ep->flag_setup = '-';
+	ep->flag_data = 'E';
+
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+
+	wake_up(&rp->b_wait);
+}
+
+static int mon_bin_open(struct inode *inode, struct file *file)
+{
+	struct mon_bus *mbus;
+	struct mon_reader_bin *rp;
+	size_t size;
+	int rc;
+
+	mutex_lock(&mon_lock);
+	mbus = mon_bus_lookup(iminor(inode));
+	if (mbus == NULL) {
+		mutex_unlock(&mon_lock);
+		return -ENODEV;
+	}
+	if (mbus != &mon_bus0 && mbus->u_bus == NULL) {
+		printk(KERN_ERR TAG ": consistency error on open\n");
+		mutex_unlock(&mon_lock);
+		return -ENODEV;
+	}
+
+	rp = kzalloc_obj(struct mon_reader_bin);
+	if (rp == NULL) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	spin_lock_init(&rp->b_lock);
+	init_waitqueue_head(&rp->b_wait);
+	mutex_init(&rp->fetch_lock);
+	rp->b_size = BUFF_DFL;
+
+	size = sizeof(struct mon_pgmap) * (rp->b_size/CHUNK_SIZE);
+	if ((rp->b_vec = kzalloc(size, GFP_KERNEL)) == NULL) {
+		rc = -ENOMEM;
+		goto err_allocvec;
+	}
+
+	if ((rc = mon_alloc_buff(rp->b_vec, rp->b_size/CHUNK_SIZE)) < 0)
+		goto err_allocbuff;
+
+	rp->r.m_bus = mbus;
+	rp->r.r_data = rp;
+	rp->r.rnf_submit = mon_bin_submit;
+	rp->r.rnf_error = mon_bin_error;
+	rp->r.rnf_complete = mon_bin_complete;
+
+	mon_reader_add(mbus, &rp->r);
+
+	file->private_data = rp;
+	mutex_unlock(&mon_lock);
+	return 0;
+
+err_allocbuff:
+	kfree(rp->b_vec);
+err_allocvec:
+	kfree(rp);
+err_alloc:
+	mutex_unlock(&mon_lock);
+	return rc;
+}
+
+/*
+ * Extract an event from buffer and copy it to user space.
+ * Wait if there is no event ready.
+ * Returns zero or error.
+ */
+static int mon_bin_get_event(struct file *file, struct mon_reader_bin *rp,
+    struct mon_bin_hdr __user *hdr, unsigned int hdrbytes,
+    void __user *data, unsigned int nbytes)
+{
+	unsigned long flags;
+	struct mon_bin_hdr *ep;
+	size_t step_len;
+	unsigned int offset;
+	int rc;
+
+	mutex_lock(&rp->fetch_lock);
+
+	if ((rc = mon_bin_wait_event(file, rp)) < 0) {
+		mutex_unlock(&rp->fetch_lock);
+		return rc;
+	}
+
+	ep = MON_OFF2HDR(rp, rp->b_out);
+
+	if (copy_to_user(hdr, ep, hdrbytes)) {
+		mutex_unlock(&rp->fetch_lock);
+		return -EFAULT;
+	}
+
+	step_len = min(ep->len_cap, nbytes);
+	if ((offset = rp->b_out + PKT_SIZE) >= rp->b_size) offset = 0;
+
+	if (copy_from_buf(rp, offset, data, step_len)) {
+		mutex_unlock(&rp->fetch_lock);
+		return -EFAULT;
+	}
+
+	spin_lock_irqsave(&rp->b_lock, flags);
+	mon_buff_area_free(rp, PKT_SIZE + ep->len_cap);
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+	rp->b_read = 0;
+
+	mutex_unlock(&rp->fetch_lock);
+	return 0;
+}
+
+static int mon_bin_release(struct inode *inode, struct file *file)
+{
+	struct mon_reader_bin *rp = file->private_data;
+	struct mon_bus* mbus = rp->r.m_bus;
+
+	mutex_lock(&mon_lock);
+
+	if (mbus->nreaders <= 0) {
+		printk(KERN_ERR TAG ": consistency error on close\n");
+		mutex_unlock(&mon_lock);
+		return 0;
+	}
+	mon_reader_del(mbus, &rp->r);
+
+	mon_free_buff(rp->b_vec, rp->b_size/CHUNK_SIZE);
+	kfree(rp->b_vec);
+	kfree(rp);
+
+	mutex_unlock(&mon_lock);
+	return 0;
+}
+
+static ssize_t mon_bin_read(struct file *file, char __user *buf,
+    size_t nbytes, loff_t *ppos)
+{
+	struct mon_reader_bin *rp = file->private_data;
+	unsigned int hdrbytes = PKT_SZ_API0;
+	unsigned long flags;
+	struct mon_bin_hdr *ep;
+	unsigned int offset;
+	size_t step_len;
+	char *ptr;
+	ssize_t done = 0;
+	int rc;
+
+	mutex_lock(&rp->fetch_lock);
+
+	if ((rc = mon_bin_wait_event(file, rp)) < 0) {
+		mutex_unlock(&rp->fetch_lock);
+		return rc;
+	}
+
+	ep = MON_OFF2HDR(rp, rp->b_out);
+
+	if (rp->b_read < hdrbytes) {
+		step_len = min_t(size_t, nbytes, hdrbytes - rp->b_read);
+		ptr = ((char *)ep) + rp->b_read;
+		if (step_len && copy_to_user(buf, ptr, step_len)) {
+			mutex_unlock(&rp->fetch_lock);
+			return -EFAULT;
+		}
+		nbytes -= step_len;
+		buf += step_len;
+		rp->b_read += step_len;
+		done += step_len;
+	}
+
+	if (rp->b_read >= hdrbytes) {
+		step_len = ep->len_cap;
+		step_len -= rp->b_read - hdrbytes;
+		if (step_len > nbytes)
+			step_len = nbytes;
+		offset = rp->b_out + PKT_SIZE;
+		offset += rp->b_read - hdrbytes;
+		if (offset >= rp->b_size)
+			offset -= rp->b_size;
+		if (copy_from_buf(rp, offset, buf, step_len)) {
+			mutex_unlock(&rp->fetch_lock);
+			return -EFAULT;
+		}
+		nbytes -= step_len;
+		buf += step_len;
+		rp->b_read += step_len;
+		done += step_len;
+	}
+
+	/*
+	 * Check if whole packet was read, and if so, jump to the next one.
+	 */
+	if (rp->b_read >= hdrbytes + ep->len_cap) {
+		spin_lock_irqsave(&rp->b_lock, flags);
+		mon_buff_area_free(rp, PKT_SIZE + ep->len_cap);
+		spin_unlock_irqrestore(&rp->b_lock, flags);
+		rp->b_read = 0;
+	}
+
+	mutex_unlock(&rp->fetch_lock);
+	return done;
+}
+
+/*
+ * Remove at most nevents from chunked buffer.
+ * Returns the number of removed events.
+ */
+static int mon_bin_flush(struct mon_reader_bin *rp, unsigned nevents)
+{
+	unsigned long flags;
+	struct mon_bin_hdr *ep;
+	int i;
+
+	mutex_lock(&rp->fetch_lock);
+	spin_lock_irqsave(&rp->b_lock, flags);
+	for (i = 0; i < nevents; ++i) {
+		if (MON_RING_EMPTY(rp))
+			break;
+
+		ep = MON_OFF2HDR(rp, rp->b_out);
+		mon_buff_area_free(rp, PKT_SIZE + ep->len_cap);
+	}
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+	rp->b_read = 0;
+	mutex_unlock(&rp->fetch_lock);
+	return i;
+}
+
+/*
+ * Fetch at most max event offsets into the buffer and put them into vec.
+ * The events are usually freed later with mon_bin_flush.
+ * Return the effective number of events fetched.
+ */
+static int mon_bin_fetch(struct file *file, struct mon_reader_bin *rp,
+    u32 __user *vec, unsigned int max)
+{
+	unsigned int cur_out;
+	unsigned int bytes, avail;
+	unsigned int size;
+	unsigned int nevents;
+	struct mon_bin_hdr *ep;
+	unsigned long flags;
+	int rc;
+
+	mutex_lock(&rp->fetch_lock);
+
+	if ((rc = mon_bin_wait_event(file, rp)) < 0) {
+		mutex_unlock(&rp->fetch_lock);
+		return rc;
+	}
+
+	spin_lock_irqsave(&rp->b_lock, flags);
+	avail = rp->b_cnt;
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+
+	cur_out = rp->b_out;
+	nevents = 0;
+	bytes = 0;
+	while (bytes < avail) {
+		if (nevents >= max)
+			break;
+
+		ep = MON_OFF2HDR(rp, cur_out);
+		if (put_user(cur_out, &vec[nevents])) {
+			mutex_unlock(&rp->fetch_lock);
+			return -EFAULT;
+		}
+
+		nevents++;
+		size = ep->len_cap + PKT_SIZE;
+		size = (size + PKT_ALIGN-1) & ~(PKT_ALIGN-1);
+		if ((cur_out += size) >= rp->b_size)
+			cur_out -= rp->b_size;
+		bytes += size;
+	}
+
+	mutex_unlock(&rp->fetch_lock);
+	return nevents;
+}
+
+/*
+ * Count events. This is almost the same as the above mon_bin_fetch,
+ * only we do not store offsets into user vector, and we have no limit.
+ */
+static int mon_bin_queued(struct mon_reader_bin *rp)
+{
+	unsigned int cur_out;
+	unsigned int bytes, avail;
+	unsigned int size;
+	unsigned int nevents;
+	struct mon_bin_hdr *ep;
+	unsigned long flags;
+
+	mutex_lock(&rp->fetch_lock);
+
+	spin_lock_irqsave(&rp->b_lock, flags);
+	avail = rp->b_cnt;
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+
+	cur_out = rp->b_out;
+	nevents = 0;
+	bytes = 0;
+	while (bytes < avail) {
+		ep = MON_OFF2HDR(rp, cur_out);
+
+		nevents++;
+		size = ep->len_cap + PKT_SIZE;
+		size = (size + PKT_ALIGN-1) & ~(PKT_ALIGN-1);
+		if ((cur_out += size) >= rp->b_size)
+			cur_out -= rp->b_size;
+		bytes += size;
+	}
+
+	mutex_unlock(&rp->fetch_lock);
+	return nevents;
+}
+
+/*
+ */
+static long mon_bin_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct mon_reader_bin *rp = file->private_data;
+	// struct mon_bus* mbus = rp->r.m_bus;
+	int ret = 0;
+	struct mon_bin_hdr *ep;
+	unsigned long flags;
+
+	switch (cmd) {
+
+	case MON_IOCQ_URB_LEN:
+		/*
+		 * N.B. This only returns the size of data, without the header.
+		 */
+		spin_lock_irqsave(&rp->b_lock, flags);
+		if (!MON_RING_EMPTY(rp)) {
+			ep = MON_OFF2HDR(rp, rp->b_out);
+			ret = ep->len_cap;
+		}
+		spin_unlock_irqrestore(&rp->b_lock, flags);
+		break;
+
+	case MON_IOCQ_RING_SIZE:
+		mutex_lock(&rp->fetch_lock);
+		ret = rp->b_size;
+		mutex_unlock(&rp->fetch_lock);
+		break;
+
+	case MON_IOCT_RING_SIZE:
+		/*
+		 * Changing the buffer size will flush it's contents; the new
+		 * buffer is allocated before releasing the old one to be sure
+		 * the device will stay functional also in case of memory
+		 * pressure.
+		 */
+		{
+		int size;
+		struct mon_pgmap *vec;
+
+		if (arg < BUFF_MIN || arg > BUFF_MAX)
+			return -EINVAL;
+
+		size = CHUNK_ALIGN(arg);
+		vec = kzalloc_objs(struct mon_pgmap, size / CHUNK_SIZE);
+		if (vec == NULL) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		ret = mon_alloc_buff(vec, size/CHUNK_SIZE);
+		if (ret < 0) {
+			kfree(vec);
+			break;
+		}
+
+		mutex_lock(&rp->fetch_lock);
+		spin_lock_irqsave(&rp->b_lock, flags);
+		if (rp->mmap_active) {
+			mon_free_buff(vec, size/CHUNK_SIZE);
+			kfree(vec);
+			ret = -EBUSY;
+		} else {
+			mon_free_buff(rp->b_vec, rp->b_size/CHUNK_SIZE);
+			kfree(rp->b_vec);
+			rp->b_vec  = vec;
+			rp->b_size = size;
+			rp->b_read = rp->b_in = rp->b_out = rp->b_cnt = 0;
+			rp->cnt_lost = 0;
+		}
+		spin_unlock_irqrestore(&rp->b_lock, flags);
+		mutex_unlock(&rp->fetch_lock);
+		}
+		break;
+
+	case MON_IOCH_MFLUSH:
+		ret = mon_bin_flush(rp, arg);
+		break;
+
+	case MON_IOCX_GET:
+	case MON_IOCX_GETX:
+		{
+		struct mon_bin_get getb;
+
+		if (copy_from_user(&getb, (void __user *)arg,
+					    sizeof(struct mon_bin_get)))
+			return -EFAULT;
+
+		if (getb.alloc > 0x10000000)	/* Want to cast to u32 */
+			return -EINVAL;
+		ret = mon_bin_get_event(file, rp, getb.hdr,
+		    (cmd == MON_IOCX_GET)? PKT_SZ_API0: PKT_SZ_API1,
+		    getb.data, (unsigned int)getb.alloc);
+		}
+		break;
+
+	case MON_IOCX_MFETCH:
+		{
+		struct mon_bin_mfetch mfetch;
+		struct mon_bin_mfetch __user *uptr;
+
+		uptr = (struct mon_bin_mfetch __user *)arg;
+
+		if (copy_from_user(&mfetch, uptr, sizeof(mfetch)))
+			return -EFAULT;
+
+		if (mfetch.nflush) {
+			ret = mon_bin_flush(rp, mfetch.nflush);
+			if (ret < 0)
+				return ret;
+			if (put_user(ret, &uptr->nflush))
+				return -EFAULT;
+		}
+		ret = mon_bin_fetch(file, rp, mfetch.offvec, mfetch.nfetch);
+		if (ret < 0)
+			return ret;
+		if (put_user(ret, &uptr->nfetch))
+			return -EFAULT;
+		ret = 0;
+		}
+		break;
+
+	case MON_IOCG_STATS: {
+		struct mon_bin_stats __user *sp;
+		unsigned int nevents;
+		unsigned int ndropped;
+
+		spin_lock_irqsave(&rp->b_lock, flags);
+		ndropped = rp->cnt_lost;
+		rp->cnt_lost = 0;
+		spin_unlock_irqrestore(&rp->b_lock, flags);
+		nevents = mon_bin_queued(rp);
+
+		sp = (struct mon_bin_stats __user *)arg;
+		if (put_user(ndropped, &sp->dropped))
+			return -EFAULT;
+		if (put_user(nevents, &sp->queued))
+			return -EFAULT;
+
+		}
+		break;
+
+	default:
+		return -ENOTTY;
+	}
+
+	return ret;
+}
+
+#ifdef CONFIG_COMPAT
+static long mon_bin_compat_ioctl(struct file *file,
+    unsigned int cmd, unsigned long arg)
+{
+	struct mon_reader_bin *rp = file->private_data;
+	int ret;
+
+	switch (cmd) {
+
+	case MON_IOCX_GET32:
+	case MON_IOCX_GETX32:
+		{
+		struct mon_bin_get32 getb;
+
+		if (copy_from_user(&getb, (void __user *)arg,
+					    sizeof(struct mon_bin_get32)))
+			return -EFAULT;
+
+		ret = mon_bin_get_event(file, rp, compat_ptr(getb.hdr32),
+		    (cmd == MON_IOCX_GET32)? PKT_SZ_API0: PKT_SZ_API1,
+		    compat_ptr(getb.data32), getb.alloc32);
+		if (ret < 0)
+			return ret;
+		}
+		return 0;
+
+	case MON_IOCX_MFETCH32:
+		{
+		struct mon_bin_mfetch32 mfetch;
+		struct mon_bin_mfetch32 __user *uptr;
+
+		uptr = (struct mon_bin_mfetch32 __user *) compat_ptr(arg);
+
+		if (copy_from_user(&mfetch, uptr, sizeof(mfetch)))
+			return -EFAULT;
+
+		if (mfetch.nflush32) {
+			ret = mon_bin_flush(rp, mfetch.nflush32);
+			if (ret < 0)
+				return ret;
+			if (put_user(ret, &uptr->nflush32))
+				return -EFAULT;
+		}
+		ret = mon_bin_fetch(file, rp, compat_ptr(mfetch.offvec32),
+		    mfetch.nfetch32);
+		if (ret < 0)
+			return ret;
+		if (put_user(ret, &uptr->nfetch32))
+			return -EFAULT;
+		}
+		return 0;
+
+	case MON_IOCG_STATS:
+		return mon_bin_ioctl(file, cmd, (unsigned long) compat_ptr(arg));
+
+	case MON_IOCQ_URB_LEN:
+	case MON_IOCQ_RING_SIZE:
+	case MON_IOCT_RING_SIZE:
+	case MON_IOCH_MFLUSH:
+		return mon_bin_ioctl(file, cmd, arg);
+
+	default:
+		;
+	}
+	return -ENOTTY;
+}
+#endif /* CONFIG_COMPAT */
+
+static __poll_t
+mon_bin_poll(struct file *file, struct poll_table_struct *wait)
+{
+	struct mon_reader_bin *rp = file->private_data;
+	__poll_t mask = 0;
+	unsigned long flags;
+
+	if (file->f_mode & FMODE_READ)
+		poll_wait(file, &rp->b_wait, wait);
+
+	spin_lock_irqsave(&rp->b_lock, flags);
+	if (!MON_RING_EMPTY(rp))
+		mask |= EPOLLIN | EPOLLRDNORM;    /* readable */
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+	return mask;
+}
+
+/*
+ * open and close: just keep track of how many times the device is
+ * mapped, to use the proper memory allocation function.
+ */
+static void mon_bin_vma_open(struct vm_area_struct *vma)
+{
+	struct mon_reader_bin *rp = vma->vm_private_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&rp->b_lock, flags);
+	rp->mmap_active++;
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+}
+
+static void mon_bin_vma_close(struct vm_area_struct *vma)
+{
+	unsigned long flags;
+
+	struct mon_reader_bin *rp = vma->vm_private_data;
+	spin_lock_irqsave(&rp->b_lock, flags);
+	rp->mmap_active--;
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+}
+
+/*
+ * Map ring pages to user space.
+ */
+static vm_fault_t mon_bin_vma_fault(struct vm_fault *vmf)
+{
+	struct mon_reader_bin *rp = vmf->vma->vm_private_data;
+	unsigned long offset, chunk_idx;
+	struct page *pageptr;
+	unsigned long flags;
+
+	spin_lock_irqsave(&rp->b_lock, flags);
+	offset = vmf->pgoff << PAGE_SHIFT;
+	if (offset >= rp->b_size) {
+		spin_unlock_irqrestore(&rp->b_lock, flags);
+		return VM_FAULT_SIGBUS;
+	}
+	chunk_idx = offset / CHUNK_SIZE;
+	pageptr = rp->b_vec[chunk_idx].pg;
+	get_page(pageptr);
+	vmf->page = pageptr;
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+	return 0;
+}
+
+static const struct vm_operations_struct mon_bin_vm_ops = {
+	.open =     mon_bin_vma_open,
+	.close =    mon_bin_vma_close,
+	.fault =    mon_bin_vma_fault,
+};
+
+static int mon_bin_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	/* don't do anything here: "fault" will set up page table entries */
+	vma->vm_ops = &mon_bin_vm_ops;
+
+	if (vma->vm_flags & VM_WRITE)
+		return -EPERM;
+
+	vm_flags_mod(vma, VM_DONTEXPAND | VM_DONTDUMP, VM_MAYWRITE);
+	vma->vm_private_data = filp->private_data;
+	mon_bin_vma_open(vma);
+	return 0;
+}
+
+static const struct file_operations mon_fops_binary = {
+	.owner =	THIS_MODULE,
+	.open =		mon_bin_open,
+	.read =		mon_bin_read,
+	/* .write =	mon_text_write, */
+	.poll =		mon_bin_poll,
+	.unlocked_ioctl = mon_bin_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl =	mon_bin_compat_ioctl,
+#endif
+	.release =	mon_bin_release,
+	.mmap =		mon_bin_mmap,
+};
+
+static int mon_bin_wait_event(struct file *file, struct mon_reader_bin *rp)
+{
+	DECLARE_WAITQUEUE(waita, current);
+	unsigned long flags;
+
+	add_wait_queue(&rp->b_wait, &waita);
+	set_current_state(TASK_INTERRUPTIBLE);
+
+	spin_lock_irqsave(&rp->b_lock, flags);
+	while (MON_RING_EMPTY(rp)) {
+		spin_unlock_irqrestore(&rp->b_lock, flags);
+
+		if (file->f_flags & O_NONBLOCK) {
+			set_current_state(TASK_RUNNING);
+			remove_wait_queue(&rp->b_wait, &waita);
+			return -EWOULDBLOCK; /* Same as EAGAIN in Linux */
+		}
+		schedule();
+		if (signal_pending(current)) {
+			remove_wait_queue(&rp->b_wait, &waita);
+			return -EINTR;
+		}
+		set_current_state(TASK_INTERRUPTIBLE);
+
+		spin_lock_irqsave(&rp->b_lock, flags);
+	}
+	spin_unlock_irqrestore(&rp->b_lock, flags);
+
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&rp->b_wait, &waita);
+	return 0;
+}
+
+static int mon_alloc_buff(struct mon_pgmap *map, int npages)
+{
+	int n;
+	unsigned long vaddr;
+
+	for (n = 0; n < npages; n++) {
+		vaddr = get_zeroed_page(GFP_KERNEL);
+		if (vaddr == 0) {
+			while (n-- != 0)
+				free_page((unsigned long) map[n].ptr);
+			return -ENOMEM;
+		}
+		map[n].ptr = (unsigned char *) vaddr;
+		map[n].pg = virt_to_page((void *) vaddr);
+	}
+	return 0;
+}
+
+static void mon_free_buff(struct mon_pgmap *map, int npages)
+{
+	int n;
+
+	for (n = 0; n < npages; n++)
+		free_page((unsigned long) map[n].ptr);
+}
+
+int mon_bin_add(struct mon_bus *mbus, const struct usb_bus *ubus)
+{
+	struct device *dev;
+	unsigned minor = ubus? ubus->busnum: 0;
+
+	if (minor >= MON_BIN_MAX_MINOR)
+		return 0;
+
+	dev = device_create(&mon_bin_class, ubus ? ubus->controller : NULL,
+			    MKDEV(MAJOR(mon_bin_dev0), minor), NULL,
+			    "usbmon%d", minor);
+	if (IS_ERR(dev))
+		return 0;
+
+	mbus->classdev = dev;
+	return 1;
+}
+
+void mon_bin_del(struct mon_bus *mbus)
+{
+	device_destroy(&mon_bin_class, mbus->classdev->devt);
+}
+
+int __init mon_bin_init(void)
+{
+	int rc;
+
+	rc = class_register(&mon_bin_class);
+	if (rc)
+		goto err_class;
+
+	rc = alloc_chrdev_region(&mon_bin_dev0, 0, MON_BIN_MAX_MINOR, "usbmon");
+	if (rc < 0)
+		goto err_dev;
+
+	cdev_init(&mon_bin_cdev, &mon_fops_binary);
+	mon_bin_cdev.owner = THIS_MODULE;
+
+	rc = cdev_add(&mon_bin_cdev, mon_bin_dev0, MON_BIN_MAX_MINOR);
+	if (rc < 0)
+		goto err_add;
+
+	return 0;
+
+err_add:
+	unregister_chrdev_region(mon_bin_dev0, MON_BIN_MAX_MINOR);
+err_dev:
+	class_unregister(&mon_bin_class);
+err_class:
+	return rc;
+}
+
+void mon_bin_exit(void)
+{
+	cdev_del(&mon_bin_cdev);
+	unregister_chrdev_region(mon_bin_dev0, MON_BIN_MAX_MINOR);
+	class_unregister(&mon_bin_class);
+}
diff --git a/drivers/usb/mon/mon_main.c b/drivers/usb/mon/mon_main.c
new file mode 100644
index 000000000..e4fff194f
--- /dev/null
+++ b/drivers/usb/mon/mon_main.c
@@ -0,0 +1,423 @@
+// 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 mon_reader *r;
+
+	spin_lock_irqsave(&mbus->lock, flags);
+	mbus->cnt_events++;
+	list_for_each_entry(r, &mbus->r_list, 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 mon_reader *r;
+
+	spin_lock_irqsave(&mbus->lock, flags);
+	mbus->cnt_events++;
+	list_for_each_entry(r, &mbus->r_list, 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 mon_reader *r;
+
+	spin_lock_irqsave(&mbus->lock, flags);
+	mbus->cnt_events++;
+	list_for_each_entry(r, &mbus->r_list, 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;
+
+	if (mbus == &mon_bus0) {
+		list_for_each_entry(mbus, &mon_buses, 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_obj(struct mon_bus);
+	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 mon_bus *mbus;
+
+	if (num == 0) {
+		return &mon_bus0;
+	}
+	list_for_each_entry(mbus, &mon_buses, 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_DESCRIPTION("USB Monitor");
+MODULE_LICENSE("GPL");
diff --git a/drivers/usb/mon/mon_stat.c b/drivers/usb/mon/mon_stat.c
new file mode 100644
index 000000000..3ee2e483d
--- /dev/null
+++ b/drivers/usb/mon/mon_stat.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/slab.h>
+#include <linux/export.h>
+#include <linux/usb.h>
+#include <linux/fs.h>
+#include <linux/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;
+
+	sp = kmalloc_obj(struct snap);
+	if (sp == NULL)
+		return -ENOMEM;
+
+	mbus = inode->i_private;
+
+	sp->slen = scnprintf(sp->str, STAT_BUF_SIZE,
+			     "nreaders %d events %u text_lost %u\n",
+			     mbus->nreaders, mbus->cnt_events, 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;
+
+	return simple_read_from_buffer(buf, nbytes, ppos, sp->str, sp->slen);
+}
+
+static int mon_stat_release(struct inode *inode, struct file *file)
+{
+	struct snap *sp = file->private_data;
+	file->private_data = NULL;
+	kfree(sp);
+	return 0;
+}
+
+const struct file_operations mon_fops_stat = {
+	.owner =	THIS_MODULE,
+	.open =		mon_stat_open,
+	.read =		mon_stat_read,
+	/* .write =	mon_stat_write, */
+	/* .poll =		mon_stat_poll, */
+	/* .unlocked_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 000000000..4c8e2518e
--- /dev/null
+++ b/drivers/usb/mon/mon_text.c
@@ -0,0 +1,753 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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/slab.h>
+#include <linux/sched/signal.h>
+#include <linux/time.h>
+#include <linux/ktime.h>
+#include <linux/export.h>
+#include <linux/mutex.h>
+#include <linux/debugfs.h>
+#include <linux/scatterlist.h>
+#include <linux/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
+
+/*
+ * Defined by USB 2.0 clause 9.3, table 9.2.
+ */
+#define SETUP_MAX  8
+
+/*
+ * This limit exists to prevent OOMs when the user process stops reading.
+ * If usbmon were available to unprivileged processes, it might be open
+ * to a local DoS. But we have to keep to root in order to prevent
+ * password sniffing from HID devices.
+ */
+#define EVENT_MAX  (4*PAGE_SIZE / sizeof(struct mon_event_text))
+
+/*
+ * Potentially unlimited number; we limit it for similar allocations.
+ * The usbfs limits this to 128, but we're not quite as generous.
+ */
+#define ISODESC_MAX   5
+
+#define PRINTF_DFL  250   /* with 5 ISOs segs */
+
+struct mon_iso_desc {
+	int status;
+	unsigned int offset;
+	unsigned int length;	/* Unsigned here, signed in URB. Historic. */
+};
+
+struct mon_event_text {
+	struct list_head e_link;
+	int type;		/* submit, complete, etc. */
+	unsigned long id;	/* From pointer, most of the time */
+	unsigned int tstamp;
+	int busnum;
+	char devnum;
+	char epnum;
+	char is_in;
+	char xfertype;
+	int length;		/* Depends on type: xfer length or act length */
+	int status;
+	int interval;
+	int start_frame;
+	int error_count;
+	char setup_flag;
+	char data_flag;
+	int numdesc;		/* Full number */
+	struct mon_iso_desc isodesc[ISODESC_MAX];
+	unsigned char setup[SETUP_MAX];
+	unsigned char data[DATA_MAX];
+};
+
+#define SLAB_NAME_SZ  30
+struct mon_reader_text {
+	struct kmem_cache *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;
+	size_t printf_offset;
+	size_t printf_togo;
+	char *printf_buf;
+	struct mutex printf_lock;
+
+	char slab_name[SLAB_NAME_SZ];
+};
+
+static struct dentry *mon_dir;		/* Usually /sys/kernel/debug/usbmon */
+
+static void mon_text_ctor(void *);
+
+struct mon_text_ptr {
+	int cnt, limit;
+	char *pbuf;
+};
+
+static struct mon_event_text *
+    mon_text_read_wait(struct mon_reader_text *rp, struct file *file);
+static void mon_text_read_head_t(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep);
+static void mon_text_read_head_u(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep);
+static void mon_text_read_statset(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep);
+static void mon_text_read_intstat(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep);
+static void mon_text_read_isostat(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep);
+static void mon_text_read_isodesc(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep);
+static void mon_text_read_data(struct mon_reader_text *rp,
+    struct mon_text_ptr *p, const struct mon_event_text *ep);
+
+/*
+ * 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_setup(struct mon_event_text *ep,
+    struct urb *urb, char ev_type, struct mon_bus *mbus)
+{
+
+	if (ep->xfertype != USB_ENDPOINT_XFER_CONTROL || ev_type != 'S')
+		return '-';
+
+	if (urb->setup_packet == NULL)
+		return 'Z';	/* '0' would be not as pretty. */
+
+	memcpy(ep->setup, urb->setup_packet, SETUP_MAX);
+	return 0;
+}
+
+static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
+    int len, char ev_type, struct mon_bus *mbus)
+{
+	void *src;
+
+	if (len <= 0)
+		return 'L';
+	if (len >= DATA_MAX)
+		len = DATA_MAX;
+
+	if (ep->is_in) {
+		if (ev_type != 'C')
+			return '<';
+	} else {
+		if (ev_type != 'S')
+			return '>';
+	}
+
+	if (urb->num_sgs == 0) {
+		src = urb->transfer_buffer;
+		if (src == NULL)
+			return 'Z';	/* '0' would be not as pretty. */
+	} else {
+		struct scatterlist *sg = urb->sg;
+
+		if (PageHighMem(sg_page(sg)))
+			return 'D';
+
+		/* For the text interface we copy only the first sg buffer */
+		len = min_t(int, sg->length, len);
+		src = sg_virt(sg);
+	}
+
+	memcpy(ep->data, src, len);
+	return 0;
+}
+
+static inline unsigned int mon_get_timestamp(void)
+{
+	struct timespec64 now;
+	unsigned int stamp;
+
+	ktime_get_ts64(&now);
+	stamp = now.tv_sec & 0xFFF;  /* 2^32 = 4294967296. Limit to 4096s. */
+	stamp = stamp * USEC_PER_SEC + now.tv_nsec / NSEC_PER_USEC;
+	return stamp;
+}
+
+static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
+    char ev_type, int status)
+{
+	struct mon_event_text *ep;
+	unsigned int stamp;
+	struct usb_iso_packet_descriptor *fp;
+	struct mon_iso_desc *dp;
+	int i, ndesc;
+
+	stamp = mon_get_timestamp();
+
+	if (rp->nevents >= EVENT_MAX ||
+	    (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
+		rp->r.m_bus->cnt_text_lost++;
+		return;
+	}
+
+	ep->type = ev_type;
+	ep->id = (unsigned long) urb;
+	ep->busnum = urb->dev->bus->busnum;
+	ep->devnum = urb->dev->devnum;
+	ep->epnum = usb_endpoint_num(&urb->ep->desc);
+	ep->xfertype = usb_endpoint_type(&urb->ep->desc);
+	ep->is_in = usb_urb_dir_in(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 = status;
+
+	if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
+		ep->interval = urb->interval;
+	} else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
+		ep->interval = urb->interval;
+		ep->start_frame = urb->start_frame;
+		ep->error_count = urb->error_count;
+	}
+	ep->numdesc = urb->number_of_packets;
+	if (ep->xfertype == USB_ENDPOINT_XFER_ISOC &&
+			urb->number_of_packets > 0) {
+		if ((ndesc = urb->number_of_packets) > ISODESC_MAX)
+			ndesc = ISODESC_MAX;
+		fp = urb->iso_frame_desc;
+		dp = ep->isodesc;
+		for (i = 0; i < ndesc; i++) {
+			dp->status = fp->status;
+			dp->offset = fp->offset;
+			dp->length = (ev_type == 'S') ?
+			    fp->length : fp->actual_length;
+			fp++;
+			dp++;
+		}
+		/* Wasteful, but simple to understand: ISO 'C' is sparse. */
+		if (ev_type == 'C')
+			ep->length = urb->transfer_buffer_length;
+	}
+
+	ep->setup_flag = mon_text_get_setup(ep, urb, ev_type, rp->r.m_bus);
+	ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type,
+			rp->r.m_bus);
+
+	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', -EINPROGRESS);
+}
+
+static void mon_text_complete(void *data, struct urb *urb, int status)
+{
+	struct mon_reader_text *rp = data;
+	mon_text_event(rp, urb, 'C', status);
+}
+
+static void mon_text_error(void *data, struct urb *urb, int error)
+{
+	struct mon_reader_text *rp = data;
+	struct mon_event_text *ep;
+
+	if (rp->nevents >= EVENT_MAX ||
+	    (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
+		rp->r.m_bus->cnt_text_lost++;
+		return;
+	}
+
+	ep->type = 'E';
+	ep->id = (unsigned long) urb;
+	ep->busnum = urb->dev->bus->busnum;
+	ep->devnum = urb->dev->devnum;
+	ep->epnum = usb_endpoint_num(&urb->ep->desc);
+	ep->xfertype = usb_endpoint_type(&urb->ep->desc);
+	ep->is_in = usb_urb_dir_in(urb);
+	ep->tstamp = mon_get_timestamp();
+	ep->length = 0;
+	ep->status = error;
+
+	ep->setup_flag = '-';
+	ep->data_flag = 'E';
+
+	rp->nevents++;
+	list_add_tail(&ep->e_link, &rp->e_list);
+	wake_up(&rp->wait);
+}
+
+/*
+ * 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 mon_reader_text *rp;
+	int rc;
+
+	mutex_lock(&mon_lock);
+	mbus = inode->i_private;
+
+	rp = kzalloc_obj(struct mon_reader_text);
+	if (rp == NULL) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	INIT_LIST_HEAD(&rp->e_list);
+	init_waitqueue_head(&rp->wait);
+	mutex_init(&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_error = mon_text_error;
+	rp->r.rnf_complete = mon_text_complete;
+
+	scnprintf(rp->slab_name, SLAB_NAME_SZ, "mon_text_%p", rp);
+	rp->e_slab = kmem_cache_create(rp->slab_name,
+	    sizeof(struct mon_event_text), sizeof(long), 0,
+	    mon_text_ctor);
+	if (rp->e_slab == NULL) {
+		rc = -ENOMEM;
+		goto err_slab;
+	}
+
+	mon_reader_add(mbus, &rp->r);
+
+	file->private_data = rp;
+	mutex_unlock(&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:
+	mutex_unlock(&mon_lock);
+	return rc;
+}
+
+static ssize_t mon_text_copy_to_user(struct mon_reader_text *rp,
+    char __user * const buf, const size_t nbytes)
+{
+	const size_t togo = min(nbytes, rp->printf_togo);
+
+	if (copy_to_user(buf, &rp->printf_buf[rp->printf_offset], togo))
+		return -EFAULT;
+	rp->printf_togo -= togo;
+	rp->printf_offset += togo;
+	return togo;
+}
+
+/* ppos is not advanced since the llseek operation is not permitted. */
+static ssize_t mon_text_read_t(struct file *file, char __user *buf,
+    size_t nbytes, loff_t *ppos)
+{
+	struct mon_reader_text *rp = file->private_data;
+	struct mon_event_text *ep;
+	struct mon_text_ptr ptr;
+	ssize_t ret;
+
+	mutex_lock(&rp->printf_lock);
+
+	if (rp->printf_togo == 0) {
+
+		ep = mon_text_read_wait(rp, file);
+		if (IS_ERR(ep)) {
+			mutex_unlock(&rp->printf_lock);
+			return PTR_ERR(ep);
+		}
+		ptr.cnt = 0;
+		ptr.pbuf = rp->printf_buf;
+		ptr.limit = rp->printf_size;
+
+		mon_text_read_head_t(rp, &ptr, ep);
+		mon_text_read_statset(rp, &ptr, ep);
+		ptr.cnt += scnprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
+		    " %d", ep->length);
+		mon_text_read_data(rp, &ptr, ep);
+
+		rp->printf_togo = ptr.cnt;
+		rp->printf_offset = 0;
+
+		kmem_cache_free(rp->e_slab, ep);
+	}
+
+	ret = mon_text_copy_to_user(rp, buf, nbytes);
+	mutex_unlock(&rp->printf_lock);
+	return ret;
+}
+
+/* ppos is not advanced since the llseek operation is not permitted. */
+static ssize_t mon_text_read_u(struct file *file, char __user *buf,
+    size_t nbytes, loff_t *ppos)
+{
+	struct mon_reader_text *rp = file->private_data;
+	struct mon_event_text *ep;
+	struct mon_text_ptr ptr;
+	ssize_t ret;
+
+	mutex_lock(&rp->printf_lock);
+
+	if (rp->printf_togo == 0) {
+
+		ep = mon_text_read_wait(rp, file);
+		if (IS_ERR(ep)) {
+			mutex_unlock(&rp->printf_lock);
+			return PTR_ERR(ep);
+		}
+		ptr.cnt = 0;
+		ptr.pbuf = rp->printf_buf;
+		ptr.limit = rp->printf_size;
+
+		mon_text_read_head_u(rp, &ptr, ep);
+		if (ep->type == 'E') {
+			mon_text_read_statset(rp, &ptr, ep);
+		} else if (ep->xfertype == USB_ENDPOINT_XFER_ISOC) {
+			mon_text_read_isostat(rp, &ptr, ep);
+			mon_text_read_isodesc(rp, &ptr, ep);
+		} else if (ep->xfertype == USB_ENDPOINT_XFER_INT) {
+			mon_text_read_intstat(rp, &ptr, ep);
+		} else {
+			mon_text_read_statset(rp, &ptr, ep);
+		}
+		ptr.cnt += scnprintf(ptr.pbuf + ptr.cnt, ptr.limit - ptr.cnt,
+		    " %d", ep->length);
+		mon_text_read_data(rp, &ptr, ep);
+
+		rp->printf_togo = ptr.cnt;
+		rp->printf_offset = 0;
+
+		kmem_cache_free(rp->e_slab, ep);
+	}
+
+	ret = mon_text_copy_to_user(rp, buf, nbytes);
+	mutex_unlock(&rp->printf_lock);
+	return ret;
+}
+
+static struct mon_event_text *mon_text_read_wait(struct mon_reader_text *rp,
+    struct file *file)
+{
+	struct mon_bus *mbus = rp->r.m_bus;
+	DECLARE_WAITQUEUE(waita, current);
+	struct mon_event_text *ep;
+
+	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 ERR_PTR(-EWOULDBLOCK);
+		}
+		/*
+		 * 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 ERR_PTR(-EINTR);
+		}
+		set_current_state(TASK_INTERRUPTIBLE);
+	}
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&rp->wait, &waita);
+	return ep;
+}
+
+static void mon_text_read_head_t(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep)
+{
+	char udir, utype;
+
+	udir = (ep->is_in ? 'i' : 'o');
+	switch (ep->xfertype) {
+	case USB_ENDPOINT_XFER_ISOC:	utype = 'Z'; break;
+	case USB_ENDPOINT_XFER_INT:	utype = 'I'; break;
+	case USB_ENDPOINT_XFER_CONTROL:	utype = 'C'; break;
+	default: /* PIPE_BULK */  utype = 'B';
+	}
+	p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+	    "%lx %u %c %c%c:%03u:%02u",
+	    ep->id, ep->tstamp, ep->type,
+	    utype, udir, ep->devnum, ep->epnum);
+}
+
+static void mon_text_read_head_u(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep)
+{
+	char udir, utype;
+
+	udir = (ep->is_in ? 'i' : 'o');
+	switch (ep->xfertype) {
+	case USB_ENDPOINT_XFER_ISOC:	utype = 'Z'; break;
+	case USB_ENDPOINT_XFER_INT:	utype = 'I'; break;
+	case USB_ENDPOINT_XFER_CONTROL:	utype = 'C'; break;
+	default: /* PIPE_BULK */  utype = 'B';
+	}
+	p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+	    "%lx %u %c %c%c:%d:%03u:%u",
+	    ep->id, ep->tstamp, ep->type,
+	    utype, udir, ep->busnum, ep->devnum, ep->epnum);
+}
+
+static void mon_text_read_statset(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep)
+{
+
+	if (ep->setup_flag == 0) {   /* Setup packet is present and captured */
+		p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+		    " s %02x %02x %04x %04x %04x",
+		    ep->setup[0],
+		    ep->setup[1],
+		    (ep->setup[3] << 8) | ep->setup[2],
+		    (ep->setup[5] << 8) | ep->setup[4],
+		    (ep->setup[7] << 8) | ep->setup[6]);
+	} else if (ep->setup_flag != '-') { /* Unable to capture setup packet */
+		p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+		    " %c __ __ ____ ____ ____", ep->setup_flag);
+	} else {                     /* No setup for this kind of URB */
+		p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+		    " %d", ep->status);
+	}
+}
+
+static void mon_text_read_intstat(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep)
+{
+	p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+	    " %d:%d", ep->status, ep->interval);
+}
+
+static void mon_text_read_isostat(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep)
+{
+	if (ep->type == 'S') {
+		p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+		    " %d:%d:%d", ep->status, ep->interval, ep->start_frame);
+	} else {
+		p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+		    " %d:%d:%d:%d",
+		    ep->status, ep->interval, ep->start_frame, ep->error_count);
+	}
+}
+
+static void mon_text_read_isodesc(struct mon_reader_text *rp,
+	struct mon_text_ptr *p, const struct mon_event_text *ep)
+{
+	int ndesc;	/* Display this many */
+	int i;
+	const struct mon_iso_desc *dp;
+
+	p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+	    " %d", ep->numdesc);
+	ndesc = ep->numdesc;
+	if (ndesc > ISODESC_MAX)
+		ndesc = ISODESC_MAX;
+	if (ndesc < 0)
+		ndesc = 0;
+	dp = ep->isodesc;
+	for (i = 0; i < ndesc; i++) {
+		p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+		    " %d:%u:%u", dp->status, dp->offset, dp->length);
+		dp++;
+	}
+}
+
+static void mon_text_read_data(struct mon_reader_text *rp,
+    struct mon_text_ptr *p, const struct mon_event_text *ep)
+{
+	int data_len, i;
+
+	if ((data_len = ep->length) > 0) {
+		if (ep->data_flag == 0) {
+			p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+			    " =");
+			if (data_len >= DATA_MAX)
+				data_len = DATA_MAX;
+			for (i = 0; i < data_len; i++) {
+				if (i % 4 == 0) {
+					p->cnt += scnprintf(p->pbuf + p->cnt,
+					    p->limit - p->cnt,
+					    " ");
+				}
+				p->cnt += scnprintf(p->pbuf + p->cnt,
+				    p->limit - p->cnt,
+				    "%02x", ep->data[i]);
+			}
+			p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+			    "\n");
+		} else {
+			p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt,
+			    " %c\n", ep->data_flag);
+		}
+	} else {
+		p->cnt += scnprintf(p->pbuf + p->cnt, p->limit - p->cnt, "\n");
+	}
+}
+
+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;
+
+	mutex_lock(&mon_lock);
+	mbus = inode->i_private;
+
+	if (mbus->nreaders <= 0) {
+		printk(KERN_ERR TAG ": consistency error on close\n");
+		mutex_unlock(&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);
+
+	mutex_unlock(&mon_lock);
+	return 0;
+}
+
+static const struct file_operations mon_fops_text_t = {
+	.owner =	THIS_MODULE,
+	.open =		mon_text_open,
+	.read =		mon_text_read_t,
+	.release =	mon_text_release,
+};
+
+static const struct file_operations mon_fops_text_u = {
+	.owner =	THIS_MODULE,
+	.open =		mon_text_open,
+	.read =		mon_text_read_u,
+	.release =	mon_text_release,
+};
+
+int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus)
+{
+	enum { NAMESZ = 12 };
+	char name[NAMESZ];
+	int busnum = ubus? ubus->busnum: 0;
+
+	if (mon_dir == NULL)
+		return 0;
+
+	if (ubus != NULL) {
+		scnprintf(name, NAMESZ, "%dt", busnum);
+		mbus->dent_t = debugfs_create_file(name, 0600, mon_dir, mbus,
+							     &mon_fops_text_t);
+	}
+
+	scnprintf(name, NAMESZ, "%du", busnum);
+	mbus->dent_u = debugfs_create_file(name, 0600, mon_dir, mbus,
+					   &mon_fops_text_u);
+
+	scnprintf(name, NAMESZ, "%ds", busnum);
+	mbus->dent_s = debugfs_create_file(name, 0600, mon_dir, mbus,
+					   &mon_fops_stat);
+
+	return 1;
+}
+
+void mon_text_del(struct mon_bus *mbus)
+{
+	debugfs_remove(mbus->dent_u);
+	debugfs_remove(mbus->dent_t);
+	debugfs_remove(mbus->dent_s);
+}
+
+/*
+ * Slab interface: constructor.
+ */
+static void mon_text_ctor(void *mem)
+{
+	/*
+	 * Nothing to initialize. No, really!
+	 * So, we fill it with garbage to emulate a reused object.
+	 */
+	memset(mem, 0xe5, sizeof(struct mon_event_text));
+}
+
+int __init mon_text_init(void)
+{
+	mon_dir = debugfs_create_dir("usbmon", usb_debug_root);
+	return 0;
+}
+
+void mon_text_exit(void)
+{
+	debugfs_remove(mon_dir);
+}
diff --git a/drivers/usb/mon/usb_mon.h b/drivers/usb/mon/usb_mon.h
new file mode 100644
index 000000000..aa64efaba
--- /dev/null
+++ b/drivers/usb/mon/usb_mon.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * The USB Monitor, inspired by Dave Harding's USBMon.
+ *
+ * Copyright (C) 2005 Pete Zaitcev (zaitcev@redhat.com)
+ */
+
+#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 usb_bus *u_bus;
+
+	int text_inited;
+	int bin_inited;
+	struct dentry *dent_s;		/* Debugging file */
+	struct dentry *dent_t;		/* Text interface file */
+	struct dentry *dent_u;		/* Second text interface file */
+	struct device *classdev;	/* Device in usbmon class */
+
+	/* 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_events;
+	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_error)(void *data, struct urb *urb, int error);
+	void (*rnf_complete)(void *data, struct urb *urb, int status);
+};
+
+void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r);
+void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r);
+
+struct mon_bus *mon_bus_lookup(unsigned int num);
+
+int /*bool*/ mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus);
+void mon_text_del(struct mon_bus *mbus);
+int /*bool*/ mon_bin_add(struct mon_bus *mbus, const struct usb_bus *ubus);
+void mon_bin_del(struct mon_bus *mbus);
+
+int __init mon_text_init(void);
+void mon_text_exit(void);
+int __init mon_bin_init(void);
+void mon_bin_exit(void);
+
+/*
+ */
+extern struct mutex mon_lock;
+
+extern const struct file_operations mon_fops_stat;
+
+extern struct mon_bus mon_bus0;		/* Only for redundant checks */
+
+#endif /* __USB_MON_H */