mm owner: fix race between swapoff and exit

[linux-2.6/next.git] / drivers / usb / core / devices.c

/*
 * devices.c
 * (C) Copyright 1999 Randy Dunlap.
 * (C) Copyright 1999,2000 Thomas Sailer <sailer@ife.ee.ethz.ch>. (proc file per device)
 * (C) Copyright 1999 Deti Fliegl (new USB architecture)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *************************************************************
 *
 * <mountpoint>/devices contains USB topology, device, config, class,
 * interface, & endpoint data.
 *
 * I considered using /proc/bus/usb/devices/device# for each device
 * as it is attached or detached, but I didn't like this for some
 * reason -- maybe it's just too deep of a directory structure.
 * I also don't like looking in multiple places to gather and view
 * the data.  Having only one file for ./devices also prevents race
 * conditions that could arise if a program was reading device info
 * for devices that are being removed (unplugged).  (That is, the
 * program may find a directory for devnum_12 then try to open it,
 * but it was just unplugged, so the directory is now deleted.
 * But programs would just have to be prepared for situations like
 * this in any plug-and-play environment.)
 *
 * 1999-12-16: Thomas Sailer <sailer@ife.ee.ethz.ch>
 *   Converted the whole proc stuff to real
 *   read methods. Now not the whole device list needs to fit
 *   into one page, only the device list for one bus.
 *   Added a poll method to /proc/bus/usb/devices, to wake
 *   up an eventual usbd
 * 2000-01-04: Thomas Sailer <sailer@ife.ee.ethz.ch>
 *   Turned into its own filesystem
 * 2000-07-05: Ashley Montanaro <ashley@compsoc.man.ac.uk>
 *   Converted file reading routine to dump to buffer once
 *   per device, not per bus
 */

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/usb.h>
#include <linux/smp_lock.h>
#include <linux/usbdevice_fs.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>

#include "usb.h"
#include "hcd.h"

/* Define ALLOW_SERIAL_NUMBER if you want to see the serial number of devices */
#define ALLOW_SERIAL_NUMBER

static const char *format_topo =
/* T:  Bus=dd Lev=dd Prnt=dd Port=dd Cnt=dd Dev#=ddd Spd=ddd MxCh=dd */
"\nT:  Bus=%2.2d Lev=%2.2d Prnt=%2.2d Port=%2.2d Cnt=%2.2d Dev#=%3d Spd=%3s MxCh=%2d\n";

static const char *format_string_manufacturer =
/* S:  Manufacturer=xxxx */
  "S:  Manufacturer=%.100s\n";

static const char *format_string_product =
/* S:  Product=xxxx */
  "S:  Product=%.100s\n";

#ifdef ALLOW_SERIAL_NUMBER
static const char *format_string_serialnumber =
/* S:  SerialNumber=xxxx */
  "S:  SerialNumber=%.100s\n";
#endif

static const char *format_bandwidth =
/* B:  Alloc=ddd/ddd us (xx%), #Int=ddd, #Iso=ddd */
  "B:  Alloc=%3d/%3d us (%2d%%), #Int=%3d, #Iso=%3d\n";

static const char *format_device1 =
/* D:  Ver=xx.xx Cls=xx(sssss) Sub=xx Prot=xx MxPS=dd #Cfgs=dd */
  "D:  Ver=%2x.%02x Cls=%02x(%-5s) Sub=%02x Prot=%02x MxPS=%2d #Cfgs=%3d\n";

static const char *format_device2 =
/* P:  Vendor=xxxx ProdID=xxxx Rev=xx.xx */
  "P:  Vendor=%04x ProdID=%04x Rev=%2x.%02x\n";

static const char *format_config =
/* C:  #Ifs=dd Cfg#=dd Atr=xx MPwr=dddmA */
  "C:%c #Ifs=%2d Cfg#=%2d Atr=%02x MxPwr=%3dmA\n";

static const char *format_iad =
/* A:  FirstIf#=dd IfCount=dd Cls=xx(sssss) Sub=xx Prot=xx */
  "A:  FirstIf#=%2d IfCount=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x\n";

static const char *format_iface =
/* I:  If#=dd Alt=dd #EPs=dd Cls=xx(sssss) Sub=xx Prot=xx Driver=xxxx*/
  "I:%c If#=%2d Alt=%2d #EPs=%2d Cls=%02x(%-5s) Sub=%02x Prot=%02x Driver=%s\n";

static const char *format_endpt =
/* E:  Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=D?s */
  "E:  Ad=%02x(%c) Atr=%02x(%-4s) MxPS=%4d Ivl=%d%cs\n";


/*
 * Need access to the driver and USB bus lists.
 * extern struct list_head usb_bus_list;
 * However, these will come from functions that return ptrs to each of them.
 */

static DECLARE_WAIT_QUEUE_HEAD(deviceconndiscwq);
static unsigned int conndiscevcnt;

/* this struct stores the poll state for <mountpoint>/devices pollers */
struct usb_device_status {
        unsigned int lastev;
};

struct class_info {
        int class;
        char *class_name;
};

static const struct class_info clas_info[] =
{                                       /* max. 5 chars. per name string */
        {USB_CLASS_PER_INTERFACE,       ">ifc"},
        {USB_CLASS_AUDIO,               "audio"},
        {USB_CLASS_COMM,                "comm."},
        {USB_CLASS_HID,                 "HID"},
        {USB_CLASS_HUB,                 "hub"},
        {USB_CLASS_PHYSICAL,            "PID"},
        {USB_CLASS_PRINTER,             "print"},
        {USB_CLASS_MASS_STORAGE,        "stor."},
        {USB_CLASS_CDC_DATA,            "data"},
        {USB_CLASS_APP_SPEC,            "app."},
        {USB_CLASS_VENDOR_SPEC,         "vend."},
        {USB_CLASS_STILL_IMAGE,         "still"},
        {USB_CLASS_CSCID,               "scard"},
        {USB_CLASS_CONTENT_SEC,         "c-sec"},
        {USB_CLASS_VIDEO,               "video"},
        {-1,                            "unk."}         /* leave as last */
};

/*****************************************************************/

void usbfs_conn_disc_event(void)
{
        conndiscevcnt++;
        wake_up(&deviceconndiscwq);
}

static const char *class_decode(const int class)
{
        int ix;

        for (ix = 0; clas_info[ix].class != -1; ix++)
                if (clas_info[ix].class == class)
                        break;
        return clas_info[ix].class_name;
}

static char *usb_dump_endpoint_descriptor(int speed, char *start, char *end,
                                const struct usb_endpoint_descriptor *desc)
{
        char dir, unit, *type;
        unsigned interval, bandwidth = 1;

        if (start > end)
                return start;

        dir = usb_endpoint_dir_in(desc) ? 'I' : 'O';

        if (speed == USB_SPEED_HIGH) {
                switch (le16_to_cpu(desc->wMaxPacketSize) & (0x03 << 11)) {
                case 1 << 11:   bandwidth = 2; break;
                case 2 << 11:   bandwidth = 3; break;
                }
        }

        /* this isn't checking for illegal values */
        switch (desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) {
        case USB_ENDPOINT_XFER_CONTROL:
                type = "Ctrl";
                if (speed == USB_SPEED_HIGH)    /* uframes per NAK */
                        interval = desc->bInterval;
                else
                        interval = 0;
                dir = 'B';                      /* ctrl is bidirectional */
                break;
        case USB_ENDPOINT_XFER_ISOC:
                type = "Isoc";
                interval = 1 << (desc->bInterval - 1);
                break;
        case USB_ENDPOINT_XFER_BULK:
                type = "Bulk";
                if (speed == USB_SPEED_HIGH && dir == 'O') /* uframes per NAK */
                        interval = desc->bInterval;
                else
                        interval = 0;
                break;
        case USB_ENDPOINT_XFER_INT:
                type = "Int.";
                if (speed == USB_SPEED_HIGH)
                        interval = 1 << (desc->bInterval - 1);
                else
                        interval = desc->bInterval;
                break;
        default:        /* "can't happen" */
                return start;
        }
        interval *= (speed == USB_SPEED_HIGH) ? 125 : 1000;
        if (interval % 1000)
                unit = 'u';
        else {
                unit = 'm';
                interval /= 1000;
        }

        start += sprintf(start, format_endpt, desc->bEndpointAddress, dir,
                         desc->bmAttributes, type,
                         (le16_to_cpu(desc->wMaxPacketSize) & 0x07ff) *
                         bandwidth,
                         interval, unit);
        return start;
}

static char *usb_dump_interface_descriptor(char *start, char *end,
                                        const struct usb_interface_cache *intfc,
                                        const struct usb_interface *iface,
                                        int setno)
{
        const struct usb_interface_descriptor *desc;
        const char *driver_name = "";
        int active = 0;

        if (start > end)
                return start;
        desc = &intfc->altsetting[setno].desc;
        if (iface) {
                driver_name = (iface->dev.driver
                                ? iface->dev.driver->name
                                : "(none)");
                active = (desc == &iface->cur_altsetting->desc);
        }
        start += sprintf(start, format_iface,
                         active ? '*' : ' ',    /* mark active altsetting */
                         desc->bInterfaceNumber,
                         desc->bAlternateSetting,
                         desc->bNumEndpoints,
                         desc->bInterfaceClass,
                         class_decode(desc->bInterfaceClass),
                         desc->bInterfaceSubClass,
                         desc->bInterfaceProtocol,
                         driver_name);
        return start;
}

static char *usb_dump_interface(int speed, char *start, char *end,
                                const struct usb_interface_cache *intfc,
                                const struct usb_interface *iface, int setno)
{
        const struct usb_host_interface *desc = &intfc->altsetting[setno];
        int i;

        start = usb_dump_interface_descriptor(start, end, intfc, iface, setno);
        for (i = 0; i < desc->desc.bNumEndpoints; i++) {
                if (start > end)
                        return start;
                start = usb_dump_endpoint_descriptor(speed,
                                start, end, &desc->endpoint[i].desc);
        }
        return start;
}

static char *usb_dump_iad_descriptor(char *start, char *end,
                        const struct usb_interface_assoc_descriptor *iad)
{
        if (start > end)
                return start;
        start += sprintf(start, format_iad,
                         iad->bFirstInterface,
                         iad->bInterfaceCount,
                         iad->bFunctionClass,
                         class_decode(iad->bFunctionClass),
                         iad->bFunctionSubClass,
                         iad->bFunctionProtocol);
        return start;
}

/* TBD:
 * 0. TBDs
 * 1. marking active interface altsettings (code lists all, but should mark
 *    which ones are active, if any)
 */
static char *usb_dump_config_descriptor(char *start, char *end,
                                const struct usb_config_descriptor *desc,
                                int active)
{
        if (start > end)
                return start;
        start += sprintf(start, format_config,
                         /* mark active/actual/current cfg. */
                         active ? '*' : ' ',
                         desc->bNumInterfaces,
                         desc->bConfigurationValue,
                         desc->bmAttributes,
                         desc->bMaxPower * 2);
        return start;
}

static char *usb_dump_config(int speed, char *start, char *end,
                             const struct usb_host_config *config, int active)
{
        int i, j;
        struct usb_interface_cache *intfc;
        struct usb_interface *interface;

        if (start > end)
                return start;
        if (!config)
                /* getting these some in 2.3.7; none in 2.3.6 */
                return start + sprintf(start, "(null Cfg. desc.)\n");
        start = usb_dump_config_descriptor(start, end, &config->desc, active);
        for (i = 0; i < USB_MAXIADS; i++) {
                if (config->intf_assoc[i] == NULL)
                        break;
                start = usb_dump_iad_descriptor(start, end,
                                        config->intf_assoc[i]);
        }
        for (i = 0; i < config->desc.bNumInterfaces; i++) {
                intfc = config->intf_cache[i];
                interface = config->interface[i];
                for (j = 0; j < intfc->num_altsetting; j++) {
                        if (start > end)
                                return start;
                        start = usb_dump_interface(speed,
                                start, end, intfc, interface, j);
                }
        }
        return start;
}

/*
 * Dump the different USB descriptors.
 */
static char *usb_dump_device_descriptor(char *start, char *end,
                                const struct usb_device_descriptor *desc)
{
        u16 bcdUSB = le16_to_cpu(desc->bcdUSB);
        u16 bcdDevice = le16_to_cpu(desc->bcdDevice);

        if (start > end)
                return start;
        start += sprintf(start, format_device1,
                          bcdUSB >> 8, bcdUSB & 0xff,
                          desc->bDeviceClass,
                          class_decode(desc->bDeviceClass),
                          desc->bDeviceSubClass,
                          desc->bDeviceProtocol,
                          desc->bMaxPacketSize0,
                          desc->bNumConfigurations);
        if (start > end)
                return start;
        start += sprintf(start, format_device2,
                         le16_to_cpu(desc->idVendor),
                         le16_to_cpu(desc->idProduct),
                         bcdDevice >> 8, bcdDevice & 0xff);
        return start;
}

/*
 * Dump the different strings that this device holds.
 */
static char *usb_dump_device_strings(char *start, char *end,
                                     struct usb_device *dev)
{
        if (start > end)
                return start;
        if (dev->manufacturer)
                start += sprintf(start, format_string_manufacturer,
                                 dev->manufacturer);
        if (start > end)
                goto out;
        if (dev->product)
                start += sprintf(start, format_string_product, dev->product);
        if (start > end)
                goto out;
#ifdef ALLOW_SERIAL_NUMBER
        if (dev->serial)
                start += sprintf(start, format_string_serialnumber,
                                 dev->serial);
#endif
 out:
        return start;
}

static char *usb_dump_desc(char *start, char *end, struct usb_device *dev)
{
        int i;

        if (start > end)
                return start;

        start = usb_dump_device_descriptor(start, end, &dev->descriptor);

        if (start > end)
                return start;

        start = usb_dump_device_strings(start, end, dev);

        for (i = 0; i < dev->descriptor.bNumConfigurations; i++) {
                if (start > end)
                        return start;
                start = usb_dump_config(dev->speed,
                                start, end, dev->config + i,
                                /* active ? */
                                (dev->config + i) == dev->actconfig);
        }
        return start;
}


#ifdef PROC_EXTRA /* TBD: may want to add this code later */

static char *usb_dump_hub_descriptor(char *start, char *end,
                                     const struct usb_hub_descriptor *desc)
{
        int leng = USB_DT_HUB_NONVAR_SIZE;
        unsigned char *ptr = (unsigned char *)desc;

        if (start > end)
                return start;
        start += sprintf(start, "Interface:");
        while (leng && start <= end) {
                start += sprintf(start, " %02x", *ptr);
                ptr++; leng--;
        }
        *start++ = '\n';
        return start;
}

static char *usb_dump_string(char *start, char *end,
                             const struct usb_device *dev, char *id, int index)
{
        if (start > end)
                return start;
        start += sprintf(start, "Interface:");
        if (index <= dev->maxstring && dev->stringindex &&
            dev->stringindex[index])
                start += sprintf(start, "%s: %.100s ", id,
                                 dev->stringindex[index]);
        return start;
}

#endif /* PROC_EXTRA */

/*****************************************************************/

/* This is a recursive function. Parameters:
 * buffer - the user-space buffer to write data into
 * nbytes - the maximum number of bytes to write
 * skip_bytes - the number of bytes to skip before writing anything
 * file_offset - the offset into the devices file on completion
 * The caller must own the device lock.
 */
static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
                               loff_t *skip_bytes, loff_t *file_offset,
                               struct usb_device *usbdev, struct usb_bus *bus,
                               int level, int index, int count)
{
        int chix;
        int ret, cnt = 0;
        int parent_devnum = 0;
        char *pages_start, *data_end, *speed;
        unsigned int length;
        ssize_t total_written = 0;

        /* don't bother with anything else if we're not writing any data */
        if (*nbytes <= 0)
                return 0;

        if (level > MAX_TOPO_LEVEL)
                return 0;
        /* allocate 2^1 pages = 8K (on i386);
         * should be more than enough for one device */
        pages_start = (char *)__get_free_pages(GFP_KERNEL, 1);
        if (!pages_start)
                return -ENOMEM;

        if (usbdev->parent && usbdev->parent->devnum != -1)
                parent_devnum = usbdev->parent->devnum;
        /*
         * So the root hub's parent is 0 and any device that is
         * plugged into the root hub has a parent of 0.
         */
        switch (usbdev->speed) {
        case USB_SPEED_LOW:
                speed = "1.5"; break;
        case USB_SPEED_UNKNOWN:         /* usb 1.1 root hub code */
        case USB_SPEED_FULL:
                speed = "12 "; break;
        case USB_SPEED_HIGH:
                speed = "480"; break;
        default:
                speed = "?? ";
        }
        data_end = pages_start + sprintf(pages_start, format_topo,
                        bus->busnum, level, parent_devnum,
                        index, count, usbdev->devnum,
                        speed, usbdev->maxchild);
        /*
         * level = topology-tier level;
         * parent_devnum = parent device number;
         * index = parent's connector number;
         * count = device count at this level
         */
        /* If this is the root hub, display the bandwidth information */
        if (level == 0) {
                int     max;

                /* high speed reserves 80%, full/low reserves 90% */
                if (usbdev->speed == USB_SPEED_HIGH)
                        max = 800;
                else
                        max = FRAME_TIME_MAX_USECS_ALLOC;

                /* report "average" periodic allocation over a microsecond.
                 * the schedules are actually bursty, HCDs need to deal with
                 * that and just compute/report this average.
                 */
                data_end += sprintf(data_end, format_bandwidth,
                                bus->bandwidth_allocated, max,
                                (100 * bus->bandwidth_allocated + max / 2)
                                        / max,
                                bus->bandwidth_int_reqs,
                                bus->bandwidth_isoc_reqs);

        }
        data_end = usb_dump_desc(data_end, pages_start + (2 * PAGE_SIZE) - 256,
                                 usbdev);

        if (data_end > (pages_start + (2 * PAGE_SIZE) - 256))
                data_end += sprintf(data_end, "(truncated)\n");

        length = data_end - pages_start;
        /* if we can start copying some data to the user */
        if (length > *skip_bytes) {
                length -= *skip_bytes;
                if (length > *nbytes)
                        length = *nbytes;
                if (copy_to_user(*buffer, pages_start + *skip_bytes, length)) {
                        free_pages((unsigned long)pages_start, 1);
                        return -EFAULT;
                }
                *nbytes -= length;
                *file_offset += length;
                total_written += length;
                *buffer += length;
                *skip_bytes = 0;
        } else
                *skip_bytes -= length;

        free_pages((unsigned long)pages_start, 1);

        /* Now look at all of this device's children. */
        for (chix = 0; chix < usbdev->maxchild; chix++) {
                struct usb_device *childdev = usbdev->children[chix];

                if (childdev) {
                        usb_lock_device(childdev);
                        ret = usb_device_dump(buffer, nbytes, skip_bytes,
                                              file_offset, childdev, bus,
                                              level + 1, chix, ++cnt);
                        usb_unlock_device(childdev);
                        if (ret == -EFAULT)
                                return total_written;
                        total_written += ret;
                }
        }
        return total_written;
}

static ssize_t usb_device_read(struct file *file, char __user *buf,
                               size_t nbytes, loff_t *ppos)
{
        struct usb_bus *bus;
        ssize_t ret, total_written = 0;
        loff_t skip_bytes = *ppos;

        if (*ppos < 0)
                return -EINVAL;
        if (nbytes <= 0)
                return 0;
        if (!access_ok(VERIFY_WRITE, buf, nbytes))
                return -EFAULT;

        mutex_lock(&usb_bus_list_lock);
        /* print devices for all busses */
        list_for_each_entry(bus, &usb_bus_list, bus_list) {
                /* recurse through all children of the root hub */
                if (!bus->root_hub)
                        continue;
                usb_lock_device(bus->root_hub);
                ret = usb_device_dump(&buf, &nbytes, &skip_bytes, ppos,
                                      bus->root_hub, bus, 0, 0, 0);
                usb_unlock_device(bus->root_hub);
                if (ret < 0) {
                        mutex_unlock(&usb_bus_list_lock);
                        return ret;
                }
                total_written += ret;
        }
        mutex_unlock(&usb_bus_list_lock);
        return total_written;
}

/* Kernel lock for "lastev" protection */
static unsigned int usb_device_poll(struct file *file,
                                    struct poll_table_struct *wait)
{
        struct usb_device_status *st = file->private_data;
        unsigned int mask = 0;

        lock_kernel();
        if (!st) {
                st = kmalloc(sizeof(struct usb_device_status), GFP_KERNEL);

                /* we may have dropped BKL -
                 * need to check for having lost the race */
                if (file->private_data) {
                        kfree(st);
                        st = file->private_data;
                        goto lost_race;
                }
                /* we haven't lost - check for allocation failure now */
                if (!st) {
                        unlock_kernel();
                        return POLLIN;
                }

                /*
                 * need to prevent the module from being unloaded, since
                 * proc_unregister does not call the release method and
                 * we would have a memory leak
                 */
                st->lastev = conndiscevcnt;
                file->private_data = st;
                mask = POLLIN;
        }
lost_race:
        if (file->f_mode & FMODE_READ)
                poll_wait(file, &deviceconndiscwq, wait);
        if (st->lastev != conndiscevcnt)
                mask |= POLLIN;
        st->lastev = conndiscevcnt;
        unlock_kernel();
        return mask;
}

static int usb_device_open(struct inode *inode, struct file *file)
{
        file->private_data = NULL;
        return 0;
}

static int usb_device_release(struct inode *inode, struct file *file)
{
        kfree(file->private_data);
        file->private_data = NULL;
        return 0;
}

static loff_t usb_device_lseek(struct file *file, loff_t offset, int orig)
{
        loff_t ret;

        lock_kernel();

        switch (orig) {
        case 0:
                file->f_pos = offset;
                ret = file->f_pos;
                break;
        case 1:
                file->f_pos += offset;
                ret = file->f_pos;
                break;
        case 2:
        default:
                ret = -EINVAL;
        }

        unlock_kernel();
        return ret;
}

const struct file_operations usbfs_devices_fops = {
        .llseek =       usb_device_lseek,
        .read =         usb_device_read,
        .poll =         usb_device_poll,
        .open =         usb_device_open,
        .release =      usb_device_release,
};