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mon_bin.c

/*
 * 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/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 unsigned char xfer_to_pipe[4] = {
      PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT
};

static struct class *mon_bin_class;
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_endpoint_xfer_control(&urb->ep->desc) || ev_type != 'S')
            return '-';

      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->dev->bus->uses_dma &&
          (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, int status)
{
      const struct usb_endpoint_descriptor *epd = &urb->ep->desc;
      unsigned long flags;
      struct timeval ts;
      unsigned int urb_length;
      unsigned int offset;
      unsigned int length;
      unsigned char dir;
      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_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);
      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 = 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_usec;
      ep->status = 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', -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;
      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 = 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->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);
      if ((mbus = mon_bus_lookup(iminor(inode))) == 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(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 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), "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;

      mon_bin_class = class_create(THIS_MODULE, "usbmon");
      if (IS_ERR(mon_bin_class)) {
            rc = PTR_ERR(mon_bin_class);
            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_destroy(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_destroy(mon_bin_class);
}

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