writeback: split writeback_inodes_wb

[linux-2.6/next.git] / net / irda / discovery.c

/*********************************************************************
 *
 * Filename:      discovery.c
 * Version:       0.1
 * Description:   Routines for handling discoveries at the IrLMP layer
 * Status:        Experimental.
 * Author:        Dag Brattli <dagb@cs.uit.no>
 * Created at:    Tue Apr  6 15:33:50 1999
 * Modified at:   Sat Oct  9 17:11:31 1999
 * Modified by:   Dag Brattli <dagb@cs.uit.no>
 * Modified at:   Fri May 28  3:11 CST 1999
 * Modified by:   Horst von Brand <vonbrand@sleipnir.valparaiso.cl>
 *
 *     Copyright (c) 1999 Dag Brattli, All Rights Reserved.
 *
 *     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
 *
 ********************************************************************/

#include <linux/string.h>
#include <linux/socket.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/slab.h>

#include <net/irda/irda.h>
#include <net/irda/irlmp.h>

#include <net/irda/discovery.h>

#include <asm/unaligned.h>

/*
 * Function irlmp_add_discovery (cachelog, discovery)
 *
 *    Add a new discovery to the cachelog, and remove any old discoveries
 *    from the same device
 *
 * Note : we try to preserve the time this device was *first* discovered
 * (as opposed to the time of last discovery used for cleanup). This is
 * used by clients waiting for discovery events to tell if the device
 * discovered is "new" or just the same old one. They can't rely there
 * on a binary flag (new/old), because not all discovery events are
 * propagated to them, and they might not always listen, so they would
 * miss some new devices popping up...
 * Jean II
 */
void irlmp_add_discovery(hashbin_t *cachelog, discovery_t *new)
{
        discovery_t *discovery, *node;
        unsigned long flags;

        /* Set time of first discovery if node is new (see below) */
        new->firststamp = new->timestamp;

        spin_lock_irqsave(&cachelog->hb_spinlock, flags);

        /*
         * Remove all discoveries of devices that has previously been
         * discovered on the same link with the same name (info), or the
         * same daddr. We do this since some devices (mostly PDAs) change
         * their device address between every discovery.
         */
        discovery = (discovery_t *) hashbin_get_first(cachelog);
        while (discovery != NULL ) {
                node = discovery;

                /* Be sure to stay one item ahead */
                discovery = (discovery_t *) hashbin_get_next(cachelog);

                if ((node->data.saddr == new->data.saddr) &&
                    ((node->data.daddr == new->data.daddr) ||
                     (strcmp(node->data.info, new->data.info) == 0)))
                {
                        /* This discovery is a previous discovery
                         * from the same device, so just remove it
                         */
                        hashbin_remove_this(cachelog, (irda_queue_t *) node);
                        /* Check if hints bits are unchanged */
                        if (get_unaligned((__u16 *)node->data.hints) == get_unaligned((__u16 *)new->data.hints))
                                /* Set time of first discovery for this node */
                                new->firststamp = node->firststamp;
                        kfree(node);
                }
        }

        /* Insert the new and updated version */
        hashbin_insert(cachelog, (irda_queue_t *) new, new->data.daddr, NULL);

        spin_unlock_irqrestore(&cachelog->hb_spinlock, flags);
}

/*
 * Function irlmp_add_discovery_log (cachelog, log)
 *
 *    Merge a disovery log into the cachelog.
 *
 */
void irlmp_add_discovery_log(hashbin_t *cachelog, hashbin_t *log)
{
        discovery_t *discovery;

        IRDA_DEBUG(4, "%s()\n", __func__);

        /*
         *  If log is missing this means that IrLAP was unable to perform the
         *  discovery, so restart discovery again with just the half timeout
         *  of the normal one.
         */
        /* Well... It means that there was nobody out there - Jean II */
        if (log == NULL) {
                /* irlmp_start_discovery_timer(irlmp, 150); */
                return;
        }

        /*
         * Locking : we are the only owner of this discovery log, so
         * no need to lock it.
         * We just need to lock the global log in irlmp_add_discovery().
         */
        discovery = (discovery_t *) hashbin_remove_first(log);
        while (discovery != NULL) {
                irlmp_add_discovery(cachelog, discovery);

                discovery = (discovery_t *) hashbin_remove_first(log);
        }

        /* Delete the now empty log */
        hashbin_delete(log, (FREE_FUNC) kfree);
}

/*
 * Function irlmp_expire_discoveries (log, saddr, force)
 *
 *    Go through all discoveries and expire all that has stayed too long
 *
 * Note : this assume that IrLAP won't change its saddr, which
 * currently is a valid assumption...
 */
void irlmp_expire_discoveries(hashbin_t *log, __u32 saddr, int force)
{
        discovery_t *           discovery;
        discovery_t *           curr;
        unsigned long           flags;
        discinfo_t *            buffer = NULL;
        int                     n;              /* Size of the full log */
        int                     i = 0;          /* How many we expired */

        IRDA_ASSERT(log != NULL, return;);
        IRDA_DEBUG(4, "%s()\n", __func__);

        spin_lock_irqsave(&log->hb_spinlock, flags);

        discovery = (discovery_t *) hashbin_get_first(log);
        while (discovery != NULL) {
                /* Be sure to be one item ahead */
                curr = discovery;
                discovery = (discovery_t *) hashbin_get_next(log);

                /* Test if it's time to expire this discovery */
                if ((curr->data.saddr == saddr) &&
                    (force ||
                     ((jiffies - curr->timestamp) > DISCOVERY_EXPIRE_TIMEOUT)))
                {
                        /* Create buffer as needed.
                         * As this function get called a lot and most time
                         * we don't have anything to put in the log (we are
                         * quite picky), we can save a lot of overhead
                         * by not calling kmalloc. Jean II */
                        if(buffer == NULL) {
                                /* Create the client specific buffer */
                                n = HASHBIN_GET_SIZE(log);
                                buffer = kmalloc(n * sizeof(struct irda_device_info), GFP_ATOMIC);
                                if (buffer == NULL) {
                                        spin_unlock_irqrestore(&log->hb_spinlock, flags);
                                        return;
                                }

                        }

                        /* Copy discovery information */
                        memcpy(&(buffer[i]), &(curr->data),
                               sizeof(discinfo_t));
                        i++;

                        /* Remove it from the log */
                        curr = hashbin_remove_this(log, (irda_queue_t *) curr);
                        kfree(curr);
                }
        }

        /* Drop the spinlock before calling the higher layers, as
         * we can't guarantee they won't call us back and create a
         * deadlock. We will work on our own private data, so we
         * don't care to be interrupted. - Jean II */
        spin_unlock_irqrestore(&log->hb_spinlock, flags);

        if(buffer == NULL)
                return;

        /* Tell IrLMP and registered clients about it */
        irlmp_discovery_expiry(buffer, i);

        /* Free up our buffer */
        kfree(buffer);
}

#if 0
/*
 * Function irlmp_dump_discoveries (log)
 *
 *    Print out all discoveries in log
 *
 */
void irlmp_dump_discoveries(hashbin_t *log)
{
        discovery_t *discovery;

        IRDA_ASSERT(log != NULL, return;);

        discovery = (discovery_t *) hashbin_get_first(log);
        while (discovery != NULL) {
                IRDA_DEBUG(0, "Discovery:\n");
                IRDA_DEBUG(0, "  daddr=%08x\n", discovery->data.daddr);
                IRDA_DEBUG(0, "  saddr=%08x\n", discovery->data.saddr);
                IRDA_DEBUG(0, "  nickname=%s\n", discovery->data.info);

                discovery = (discovery_t *) hashbin_get_next(log);
        }
}
#endif

/*
 * Function irlmp_copy_discoveries (log, pn, mask)
 *
 *    Copy all discoveries in a buffer
 *
 * This function implement a safe way for lmp clients to access the
 * discovery log. The basic problem is that we don't want the log
 * to change (add/remove) while the client is reading it. If the
 * lmp client manipulate directly the hashbin, he is sure to get
 * into troubles...
 * The idea is that we copy all the current discovery log in a buffer
 * which is specific to the client and pass this copy to him. As we
 * do this operation with the spinlock grabbed, we are safe...
 * Note : we don't want those clients to grab the spinlock, because
 * we have no control on how long they will hold it...
 * Note : we choose to copy the log in "struct irda_device_info" to
 * save space...
 * Note : the client must kfree himself() the log...
 * Jean II
 */
struct irda_device_info *irlmp_copy_discoveries(hashbin_t *log, int *pn,
                                                __u16 mask, int old_entries)
{
        discovery_t *           discovery;
        unsigned long           flags;
        discinfo_t *            buffer = NULL;
        int                     j_timeout = (sysctl_discovery_timeout * HZ);
        int                     n;              /* Size of the full log */
        int                     i = 0;          /* How many we picked */

        IRDA_ASSERT(pn != NULL, return NULL;);
        IRDA_ASSERT(log != NULL, return NULL;);

        /* Save spin lock */
        spin_lock_irqsave(&log->hb_spinlock, flags);

        discovery = (discovery_t *) hashbin_get_first(log);
        while (discovery != NULL) {
                /* Mask out the ones we don't want :
                 * We want to match the discovery mask, and to get only
                 * the most recent one (unless we want old ones) */
                if ((get_unaligned((__u16 *)discovery->data.hints) & mask) &&
                    ((old_entries) ||
                     ((jiffies - discovery->firststamp) < j_timeout))) {
                        /* Create buffer as needed.
                         * As this function get called a lot and most time
                         * we don't have anything to put in the log (we are
                         * quite picky), we can save a lot of overhead
                         * by not calling kmalloc. Jean II */
                        if(buffer == NULL) {
                                /* Create the client specific buffer */
                                n = HASHBIN_GET_SIZE(log);
                                buffer = kmalloc(n * sizeof(struct irda_device_info), GFP_ATOMIC);
                                if (buffer == NULL) {
                                        spin_unlock_irqrestore(&log->hb_spinlock, flags);
                                        return NULL;
                                }

                        }

                        /* Copy discovery information */
                        memcpy(&(buffer[i]), &(discovery->data),
                               sizeof(discinfo_t));
                        i++;
                }
                discovery = (discovery_t *) hashbin_get_next(log);
        }

        spin_unlock_irqrestore(&log->hb_spinlock, flags);

        /* Get the actual number of device in the buffer and return */
        *pn = i;
        return(buffer);
}

#ifdef CONFIG_PROC_FS
static inline discovery_t *discovery_seq_idx(loff_t pos)

{
        discovery_t *discovery;

        for (discovery = (discovery_t *) hashbin_get_first(irlmp->cachelog);
             discovery != NULL;
             discovery = (discovery_t *) hashbin_get_next(irlmp->cachelog)) {
                if (pos-- == 0)
                        break;
        }

        return discovery;
}

static void *discovery_seq_start(struct seq_file *seq, loff_t *pos)
{
        spin_lock_irq(&irlmp->cachelog->hb_spinlock);
        return *pos ? discovery_seq_idx(*pos - 1) : SEQ_START_TOKEN;
}

static void *discovery_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        ++*pos;
        return (v == SEQ_START_TOKEN)
                ? (void *) hashbin_get_first(irlmp->cachelog)
                : (void *) hashbin_get_next(irlmp->cachelog);
}

static void discovery_seq_stop(struct seq_file *seq, void *v)
{
        spin_unlock_irq(&irlmp->cachelog->hb_spinlock);
}

static int discovery_seq_show(struct seq_file *seq, void *v)
{
        if (v == SEQ_START_TOKEN)
                seq_puts(seq, "IrLMP: Discovery log:\n\n");
        else {
                const discovery_t *discovery = v;

                seq_printf(seq, "nickname: %s, hint: 0x%02x%02x",
                           discovery->data.info,
                           discovery->data.hints[0],
                           discovery->data.hints[1]);
#if 0
                if ( discovery->data.hints[0] & HINT_PNP)
                        seq_puts(seq, "PnP Compatible ");
                if ( discovery->data.hints[0] & HINT_PDA)
                        seq_puts(seq, "PDA/Palmtop ");
                if ( discovery->data.hints[0] & HINT_COMPUTER)
                        seq_puts(seq, "Computer ");
                if ( discovery->data.hints[0] & HINT_PRINTER)
                        seq_puts(seq, "Printer ");
                if ( discovery->data.hints[0] & HINT_MODEM)
                        seq_puts(seq, "Modem ");
                if ( discovery->data.hints[0] & HINT_FAX)
                        seq_puts(seq, "Fax ");
                if ( discovery->data.hints[0] & HINT_LAN)
                        seq_puts(seq, "LAN Access ");

                if ( discovery->data.hints[1] & HINT_TELEPHONY)
                        seq_puts(seq, "Telephony ");
                if ( discovery->data.hints[1] & HINT_FILE_SERVER)
                        seq_puts(seq, "File Server ");
                if ( discovery->data.hints[1] & HINT_COMM)
                        seq_puts(seq, "IrCOMM ");
                if ( discovery->data.hints[1] & HINT_OBEX)
                        seq_puts(seq, "IrOBEX ");
#endif
                seq_printf(seq,", saddr: 0x%08x, daddr: 0x%08x\n\n",
                               discovery->data.saddr,
                               discovery->data.daddr);

                seq_putc(seq, '\n');
        }
        return 0;
}

static const struct seq_operations discovery_seq_ops = {
        .start  = discovery_seq_start,
        .next   = discovery_seq_next,
        .stop   = discovery_seq_stop,
        .show   = discovery_seq_show,
};

static int discovery_seq_open(struct inode *inode, struct file *file)
{
        IRDA_ASSERT(irlmp != NULL, return -EINVAL;);

        return seq_open(file, &discovery_seq_ops);
}

const struct file_operations discovery_seq_fops = {
        .owner          = THIS_MODULE,
        .open           = discovery_seq_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};
#endif