USB: add binary API to usbmon

This patch adds a new, "binary" API in addition to the old, text API usbmon
had before. The new API allows for less CPU use, and it allows to capture
all data from a packet where old API only captured 32 bytes at most. There
are some limitations and conditions to this, e.g. in case someone constructs
a URB with 1GB of data, it's not likely to be captured, because even the
huge buffers of the new reader are finite. Nonetheless, I expect this new
capability to capture all data for all real life scenarios.

The downside is, a special user mode application is required where cat(1)
worked before. I have sample code at http://people.redhat.com/zaitcev/linux/
and Paolo Abeni is working on patching libpcap.

This patch was initially written by Paolo and later I tweaked it, and
we had a little back-and-forth. So this is a jointly authored patch, but
I am submitting this I am responsible for the bugs.

Signed-off-by: Paolo Abeni <paolo.abeni@email.it>
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1172 insertions, 0 deletions

diff --git a/drivers/usb/mon/mon_bin.c b/drivers/usb/mon/mon_bin.c
new file mode 100644
index 000000000000..c01dfe603672
--- /dev/null
+++ b/drivers/usb/mon/mon_bin.c
@@ -0,0 +1,1172 @@
+/*
+ * 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 Pete Zaitcev (zaitcev@redhat.com)
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/usb.h>
+#include <linux/poll.h>
+#include <linux/compat.h>
+#include <linux/mm.h>
+
+#include <asm/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)
+#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)
+#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.
+ * If HZ is 100, a 480 mbit/s bus drives 614 KB every jiffy. USB has an
+ * enormous overhead built into the bus protocol, so we need about 1000 KB.
+ *
+ * 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 systems with HZ=250 and incomplete bus saturation.
+ *
+ * XXX What about multi-megabyte URBs which take minutes to transfer?
+ */
+#define BUFF_MAX  CHUNK_ALIGN(1200*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;             /* gettimeofday */
+        s32 ts_usec;            /* gettimeofday */
+        int status;
+        unsigned int len_urb;   /* Length of data (submitted or actual) */
+        unsigned int len_cap;   /* Delivered length */
+        unsigned char setup[SETUP_LEN]; /* Only for Control S-type */
+};
+
+/* per file statistic */
+struct mon_bin_stats {
+        u32 queued;
+        u32 dropped;
+};
+
+struct mon_bin_get {
+        struct mon_bin_hdr __user *hdr; /* Only 48 bytes, not 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
+
+/* 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 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.
+ * But it returns the new offset for repeated application.
+ */
+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 DMA fetch fails.
+ */
+static void mon_buff_area_shrink(struct mon_reader_bin *rp, unsigned int size)
+{
+
+        size = (size + PKT_ALIGN-1) & ~(PKT_ALIGN-1);
+        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 (!usb_pipecontrol(urb->pipe) || ev_type != 'S')
+                return '-';
+
+        if (urb->transfer_flags & URB_NO_SETUP_DMA_MAP)
+                return mon_dmapeek(setupb, urb->setup_dma, SETUP_LEN);
+        if (urb->setup_packet == NULL)
+                return 'Z';
+
+        memcpy(setupb, urb->setup_packet, SETUP_LEN);
+        return 0;
+}
+
+static char mon_bin_get_data(const struct mon_reader_bin *rp,
+    unsigned int offset, struct urb *urb, unsigned int length)
+{
+
+        if (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP) {
+                mon_dmapeek_vec(rp, offset, urb->transfer_dma, length);
+                return 0;
+        }
+
+        if (urb->transfer_buffer == NULL)
+                return 'Z';
+
+        mon_copy_to_buff(rp, offset, urb->transfer_buffer, length);
+        return 0;
+}
+
+static void mon_bin_event(struct mon_reader_bin *rp, struct urb *urb,
+    char ev_type)
+{
+        unsigned long flags;
+        struct timeval ts;
+        unsigned int urb_length;
+        unsigned int offset;
+        unsigned int length;
+        struct mon_bin_hdr *ep;
+        char data_tag = 0;
+
+        do_gettimeofday(&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 (length >= rp->b_size/5)
+                length = rp->b_size/5;
+
+        if (usb_pipein(urb->pipe)) {
+                if (ev_type == 'S') {
+                        length = 0;
+                        data_tag = '<';
+                }
+        } else {
+                if (ev_type == 'C') {
+                        length = 0;
+                        data_tag = '>';
+                }
+        }
+
+        if (rp->mmap_active)
+                offset = mon_buff_area_alloc_contiguous(rp, length + PKT_SIZE);
+        else
+                offset = mon_buff_area_alloc(rp, length + PKT_SIZE);
+        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 = usb_pipetype(urb->pipe);
+        /* We use the fact that usb_pipein() returns 0x80 */
+        ep->epnum = usb_pipeendpoint(urb->pipe) | usb_pipein(urb->pipe);
+        ep->devnum = usb_pipedevice(urb->pipe);
+        ep->busnum = rp->r.m_bus->u_bus->busnum;
+        ep->id = (unsigned long) urb;
+        ep->ts_sec = ts.tv_sec;
+        ep->ts_usec = ts.tv_usec;
+        ep->status = urb->status;
+        ep->len_urb = urb_length;
+        ep->len_cap = length;
+
+        ep->flag_setup = mon_bin_get_setup(ep->setup, urb, ev_type);
+        if (length != 0) {
+                ep->flag_data = mon_bin_get_data(rp, offset, urb, length);
+                if (ep->flag_data != 0) {       /* Yes, it's 0x00, not '0' */
+                        ep->len_cap = 0;
+                        mon_buff_area_shrink(rp, length);
+                }
+        } 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');
+}
+
+static void mon_bin_complete(void *data, struct urb *urb)
+{
+        struct mon_reader_bin *rp = data;
+        mon_bin_event(rp, urb, 'C');
+}
+
+static void mon_bin_error(void *data, struct urb *urb, int error)
+{
+        struct mon_reader_bin *rp = data;
+        unsigned long flags;
+        unsigned int offset;
+        struct mon_bin_hdr *ep;
+
+        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 = usb_pipetype(urb->pipe);
+        /* We use the fact that usb_pipein() returns 0x80 */
+        ep->epnum = usb_pipeendpoint(urb->pipe) | usb_pipein(urb->pipe);
+        ep->devnum = usb_pipedevice(urb->pipe);
+        ep->busnum = rp->r.m_bus->u_bus->busnum;
+        ep->id = (unsigned long) urb;
+        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 usb_bus *ubus;
+        struct mon_reader_bin *rp;
+        size_t size;
+        int rc;
+
+        mutex_lock(&mon_lock);
+        if ((mbus = mon_bus_lookup(iminor(inode))) == NULL) {
+                mutex_unlock(&mon_lock);
+                return -ENODEV;
+        }
+        if ((ubus = mbus->u_bus) == NULL) {
+                printk(KERN_ERR TAG ": consistency error on open\n");
+                mutex_unlock(&mon_lock);
+                return -ENODEV;
+        }
+
+        rp = kzalloc(sizeof(struct mon_reader_bin), GFP_KERNEL);
+        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, 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, sizeof(struct mon_bin_hdr))) {
+                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 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 < sizeof(struct mon_bin_hdr)) {
+                step_len = min(nbytes, sizeof(struct mon_bin_hdr) - 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 >= sizeof(struct mon_bin_hdr)) {
+                step_len = min(nbytes, (size_t)ep->len_cap);
+                offset = rp->b_out + PKT_SIZE;
+                offset += rp->b_read - sizeof(struct mon_bin_hdr);
+                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 >= sizeof(struct mon_bin_hdr) + 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 int mon_bin_ioctl(struct inode *inode, 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:
+                ret = rp->b_size;
+                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);
+                if ((vec = kzalloc(sizeof(struct mon_pgmap) * (size/CHUNK_SIZE),
+                    GFP_KERNEL)) == 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);
+                mon_free_buff(rp->b_vec, 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:
+                {
+                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, getb.data, (unsigned int)getb.alloc);
+                }
+                break;
+
+#ifdef CONFIG_COMPAT
+        case MON_IOCX_GET32: {
+                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), compat_ptr(getb.data32),
+                    getb.alloc32);
+                }
+                break;
+#endif
+
+        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;
+
+#ifdef CONFIG_COMPAT
+        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;
+                ret = 0;
+                }
+                break;
+#endif
+
+        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(rp->cnt_lost, &sp->dropped))
+                        return -EFAULT;
+                if (put_user(nevents, &sp->queued))
+                        return -EFAULT;
+
+                }
+                break;
+
+        default:
+                return -ENOTTY;
+        }
+
+        return ret;
+}
+
+static unsigned int
+mon_bin_poll(struct file *file, struct poll_table_struct *wait)
+{
+        struct mon_reader_bin *rp = file->private_data;
+        unsigned int 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 |= POLLIN | POLLRDNORM;    /* 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;
+        rp->mmap_active++;
+}
+
+static void mon_bin_vma_close(struct vm_area_struct *vma)
+{
+        struct mon_reader_bin *rp = vma->vm_private_data;
+        rp->mmap_active--;
+}
+
+/*
+ * Map ring pages to user space.
+ */
+struct page *mon_bin_vma_nopage(struct vm_area_struct *vma,
+                                unsigned long address, int *type)
+{
+        struct mon_reader_bin *rp = vma->vm_private_data;
+        unsigned long offset, chunk_idx;
+        struct page *pageptr;
+
+        offset = (address - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
+        if (offset >= rp->b_size)
+                return NOPAGE_SIGBUS;
+        chunk_idx = offset / CHUNK_SIZE;
+        pageptr = rp->b_vec[chunk_idx].pg;
+        get_page(pageptr);
+        if (type)
+                *type = VM_FAULT_MINOR;
+        return pageptr;
+}
+
+struct vm_operations_struct mon_bin_vm_ops = {
+        .open =     mon_bin_vma_open,
+        .close =    mon_bin_vma_close,
+        .nopage =   mon_bin_vma_nopage,
+};
+
+int mon_bin_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+        /* don't do anything here: "nopage" will set up page table entries */
+        vma->vm_ops = &mon_bin_vm_ops;
+        vma->vm_flags |= VM_RESERVED;
+        vma->vm_private_data = filp->private_data;
+        mon_bin_vma_open(vma);
+        return 0;
+}
+
+struct file_operations mon_fops_binary = {
+        .owner =        THIS_MODULE,
+        .open =         mon_bin_open,
+        .llseek =       no_llseek,
+        .read =         mon_bin_read,
+        /* .write =     mon_text_write, */
+        .poll =         mon_bin_poll,
+        .ioctl =        mon_bin_ioctl,
+        .release =      mon_bin_release,
+};
+
+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(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 __init mon_bin_init(void)
+{
+        int rc;
+
+        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:
+        return rc;
+}
+
+void __exit mon_bin_exit(void)
+{
+        cdev_del(&mon_bin_cdev);
+        unregister_chrdev_region(mon_bin_dev0, MON_BIN_MAX_MINOR);
+}