Merge tag 'rpmsg-3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/ohad/rpmsg

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / net / wireless / scan.c

/*
 * cfg80211 scan result handling
 *
 * Copyright 2008 Johannes Berg <johannes@sipsolutions.net>
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/wireless.h>
#include <linux/nl80211.h>
#include <linux/etherdevice.h>
#include <net/arp.h>
#include <net/cfg80211.h>
#include <net/cfg80211-wext.h>
#include <net/iw_handler.h>
#include "core.h"
#include "nl80211.h"
#include "wext-compat.h"
#include "rdev-ops.h"

/**
 * DOC: BSS tree/list structure
 *
 * At the top level, the BSS list is kept in both a list in each
 * registered device (@bss_list) as well as an RB-tree for faster
 * lookup. In the RB-tree, entries can be looked up using their
 * channel, MESHID, MESHCONF (for MBSSes) or channel, BSSID, SSID
 * for other BSSes.
 *
 * Due to the possibility of hidden SSIDs, there's a second level
 * structure, the "hidden_list" and "hidden_beacon_bss" pointer.
 * The hidden_list connects all BSSes belonging to a single AP
 * that has a hidden SSID, and connects beacon and probe response
 * entries. For a probe response entry for a hidden SSID, the
 * hidden_beacon_bss pointer points to the BSS struct holding the
 * beacon's information.
 *
 * Reference counting is done for all these references except for
 * the hidden_list, so that a beacon BSS struct that is otherwise
 * not referenced has one reference for being on the bss_list and
 * one for each probe response entry that points to it using the
 * hidden_beacon_bss pointer. When a BSS struct that has such a
 * pointer is get/put, the refcount update is also propagated to
 * the referenced struct, this ensure that it cannot get removed
 * while somebody is using the probe response version.
 *
 * Note that the hidden_beacon_bss pointer never changes, due to
 * the reference counting. Therefore, no locking is needed for
 * it.
 *
 * Also note that the hidden_beacon_bss pointer is only relevant
 * if the driver uses something other than the IEs, e.g. private
 * data stored stored in the BSS struct, since the beacon IEs are
 * also linked into the probe response struct.
 */

#define IEEE80211_SCAN_RESULT_EXPIRE    (30 * HZ)

static void bss_free(struct cfg80211_internal_bss *bss)
{
        struct cfg80211_bss_ies *ies;

        if (WARN_ON(atomic_read(&bss->hold)))
                return;

        ies = (void *)rcu_access_pointer(bss->pub.beacon_ies);
        if (ies && !bss->pub.hidden_beacon_bss)
                kfree_rcu(ies, rcu_head);
        ies = (void *)rcu_access_pointer(bss->pub.proberesp_ies);
        if (ies)
                kfree_rcu(ies, rcu_head);

        /*
         * This happens when the module is removed, it doesn't
         * really matter any more save for completeness
         */
        if (!list_empty(&bss->hidden_list))
                list_del(&bss->hidden_list);

        kfree(bss);
}

static inline void bss_ref_get(struct cfg80211_registered_device *dev,
                               struct cfg80211_internal_bss *bss)
{
        lockdep_assert_held(&dev->bss_lock);

        bss->refcount++;
        if (bss->pub.hidden_beacon_bss) {
                bss = container_of(bss->pub.hidden_beacon_bss,
                                   struct cfg80211_internal_bss,
                                   pub);
                bss->refcount++;
        }
}

static inline void bss_ref_put(struct cfg80211_registered_device *dev,
                               struct cfg80211_internal_bss *bss)
{
        lockdep_assert_held(&dev->bss_lock);

        if (bss->pub.hidden_beacon_bss) {
                struct cfg80211_internal_bss *hbss;
                hbss = container_of(bss->pub.hidden_beacon_bss,
                                    struct cfg80211_internal_bss,
                                    pub);
                hbss->refcount--;
                if (hbss->refcount == 0)
                        bss_free(hbss);
        }
        bss->refcount--;
        if (bss->refcount == 0)
                bss_free(bss);
}

static bool __cfg80211_unlink_bss(struct cfg80211_registered_device *dev,
                                  struct cfg80211_internal_bss *bss)
{
        lockdep_assert_held(&dev->bss_lock);

        if (!list_empty(&bss->hidden_list)) {
                /*
                 * don't remove the beacon entry if it has
                 * probe responses associated with it
                 */
                if (!bss->pub.hidden_beacon_bss)
                        return false;
                /*
                 * if it's a probe response entry break its
                 * link to the other entries in the group
                 */
                list_del_init(&bss->hidden_list);
        }

        list_del_init(&bss->list);
        rb_erase(&bss->rbn, &dev->bss_tree);
        bss_ref_put(dev, bss);
        return true;
}

static void __cfg80211_bss_expire(struct cfg80211_registered_device *dev,
                                  unsigned long expire_time)
{
        struct cfg80211_internal_bss *bss, *tmp;
        bool expired = false;

        lockdep_assert_held(&dev->bss_lock);

        list_for_each_entry_safe(bss, tmp, &dev->bss_list, list) {
                if (atomic_read(&bss->hold))
                        continue;
                if (!time_after(expire_time, bss->ts))
                        continue;

                if (__cfg80211_unlink_bss(dev, bss))
                        expired = true;
        }

        if (expired)
                dev->bss_generation++;
}

void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev, bool leak)
{
        struct cfg80211_scan_request *request;
        struct wireless_dev *wdev;
#ifdef CONFIG_CFG80211_WEXT
        union iwreq_data wrqu;
#endif

        lockdep_assert_held(&rdev->sched_scan_mtx);

        request = rdev->scan_req;

        if (!request)
                return;

        wdev = request->wdev;

        /*
         * This must be before sending the other events!
         * Otherwise, wpa_supplicant gets completely confused with
         * wext events.
         */
        if (wdev->netdev)
                cfg80211_sme_scan_done(wdev->netdev);

        if (request->aborted) {
                nl80211_send_scan_aborted(rdev, wdev);
        } else {
                if (request->flags & NL80211_SCAN_FLAG_FLUSH) {
                        /* flush entries from previous scans */
                        spin_lock_bh(&rdev->bss_lock);
                        __cfg80211_bss_expire(rdev, request->scan_start);
                        spin_unlock_bh(&rdev->bss_lock);
                }
                nl80211_send_scan_done(rdev, wdev);
        }

#ifdef CONFIG_CFG80211_WEXT
        if (wdev->netdev && !request->aborted) {
                memset(&wrqu, 0, sizeof(wrqu));

                wireless_send_event(wdev->netdev, SIOCGIWSCAN, &wrqu, NULL);
        }
#endif

        if (wdev->netdev)
                dev_put(wdev->netdev);

        rdev->scan_req = NULL;

        /*
         * OK. If this is invoked with "leak" then we can't
         * free this ... but we've cleaned it up anyway. The
         * driver failed to call the scan_done callback, so
         * all bets are off, it might still be trying to use
         * the scan request or not ... if it accesses the dev
         * in there (it shouldn't anyway) then it may crash.
         */
        if (!leak)
                kfree(request);
}

void __cfg80211_scan_done(struct work_struct *wk)
{
        struct cfg80211_registered_device *rdev;

        rdev = container_of(wk, struct cfg80211_registered_device,
                            scan_done_wk);

        mutex_lock(&rdev->sched_scan_mtx);
        ___cfg80211_scan_done(rdev, false);
        mutex_unlock(&rdev->sched_scan_mtx);
}

void cfg80211_scan_done(struct cfg80211_scan_request *request, bool aborted)
{
        trace_cfg80211_scan_done(request, aborted);
        WARN_ON(request != wiphy_to_dev(request->wiphy)->scan_req);

        request->aborted = aborted;
        queue_work(cfg80211_wq, &wiphy_to_dev(request->wiphy)->scan_done_wk);
}
EXPORT_SYMBOL(cfg80211_scan_done);

void __cfg80211_sched_scan_results(struct work_struct *wk)
{
        struct cfg80211_registered_device *rdev;
        struct cfg80211_sched_scan_request *request;

        rdev = container_of(wk, struct cfg80211_registered_device,
                            sched_scan_results_wk);

        request = rdev->sched_scan_req;

        mutex_lock(&rdev->sched_scan_mtx);

        /* we don't have sched_scan_req anymore if the scan is stopping */
        if (request) {
                if (request->flags & NL80211_SCAN_FLAG_FLUSH) {
                        /* flush entries from previous scans */
                        spin_lock_bh(&rdev->bss_lock);
                        __cfg80211_bss_expire(rdev, request->scan_start);
                        spin_unlock_bh(&rdev->bss_lock);
                        request->scan_start =
                                jiffies + msecs_to_jiffies(request->interval);
                }
                nl80211_send_sched_scan_results(rdev, request->dev);
        }

        mutex_unlock(&rdev->sched_scan_mtx);
}

void cfg80211_sched_scan_results(struct wiphy *wiphy)
{
        trace_cfg80211_sched_scan_results(wiphy);
        /* ignore if we're not scanning */
        if (wiphy_to_dev(wiphy)->sched_scan_req)
                queue_work(cfg80211_wq,
                           &wiphy_to_dev(wiphy)->sched_scan_results_wk);
}
EXPORT_SYMBOL(cfg80211_sched_scan_results);

void cfg80211_sched_scan_stopped(struct wiphy *wiphy)
{
        struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);

        trace_cfg80211_sched_scan_stopped(wiphy);

        mutex_lock(&rdev->sched_scan_mtx);
        __cfg80211_stop_sched_scan(rdev, true);
        mutex_unlock(&rdev->sched_scan_mtx);
}
EXPORT_SYMBOL(cfg80211_sched_scan_stopped);

int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev,
                               bool driver_initiated)
{
        struct net_device *dev;

        lockdep_assert_held(&rdev->sched_scan_mtx);

        if (!rdev->sched_scan_req)
                return -ENOENT;

        dev = rdev->sched_scan_req->dev;

        if (!driver_initiated) {
                int err = rdev_sched_scan_stop(rdev, dev);
                if (err)
                        return err;
        }

        nl80211_send_sched_scan(rdev, dev, NL80211_CMD_SCHED_SCAN_STOPPED);

        kfree(rdev->sched_scan_req);
        rdev->sched_scan_req = NULL;

        return 0;
}

void cfg80211_bss_age(struct cfg80211_registered_device *dev,
                      unsigned long age_secs)
{
        struct cfg80211_internal_bss *bss;
        unsigned long age_jiffies = msecs_to_jiffies(age_secs * MSEC_PER_SEC);

        spin_lock_bh(&dev->bss_lock);
        list_for_each_entry(bss, &dev->bss_list, list)
                bss->ts -= age_jiffies;
        spin_unlock_bh(&dev->bss_lock);
}

void cfg80211_bss_expire(struct cfg80211_registered_device *dev)
{
        __cfg80211_bss_expire(dev, jiffies - IEEE80211_SCAN_RESULT_EXPIRE);
}

const u8 *cfg80211_find_ie(u8 eid, const u8 *ies, int len)
{
        while (len > 2 && ies[0] != eid) {
                len -= ies[1] + 2;
                ies += ies[1] + 2;
        }
        if (len < 2)
                return NULL;
        if (len < 2 + ies[1])
                return NULL;
        return ies;
}
EXPORT_SYMBOL(cfg80211_find_ie);

const u8 *cfg80211_find_vendor_ie(unsigned int oui, u8 oui_type,
                                  const u8 *ies, int len)
{
        struct ieee80211_vendor_ie *ie;
        const u8 *pos = ies, *end = ies + len;
        int ie_oui;

        while (pos < end) {
                pos = cfg80211_find_ie(WLAN_EID_VENDOR_SPECIFIC, pos,
                                       end - pos);
                if (!pos)
                        return NULL;

                ie = (struct ieee80211_vendor_ie *)pos;

                /* make sure we can access ie->len */
                BUILD_BUG_ON(offsetof(struct ieee80211_vendor_ie, len) != 1);

                if (ie->len < sizeof(*ie))
                        goto cont;

                ie_oui = ie->oui[0] << 16 | ie->oui[1] << 8 | ie->oui[2];
                if (ie_oui == oui && ie->oui_type == oui_type)
                        return pos;
cont:
                pos += 2 + ie->len;
        }
        return NULL;
}
EXPORT_SYMBOL(cfg80211_find_vendor_ie);

static bool is_bss(struct cfg80211_bss *a, const u8 *bssid,
                   const u8 *ssid, size_t ssid_len)
{
        const struct cfg80211_bss_ies *ies;
        const u8 *ssidie;

        if (bssid && !ether_addr_equal(a->bssid, bssid))
                return false;

        if (!ssid)
                return true;

        ies = rcu_access_pointer(a->ies);
        if (!ies)
                return false;
        ssidie = cfg80211_find_ie(WLAN_EID_SSID, ies->data, ies->len);
        if (!ssidie)
                return false;
        if (ssidie[1] != ssid_len)
                return false;
        return memcmp(ssidie + 2, ssid, ssid_len) == 0;
}

/**
 * enum bss_compare_mode - BSS compare mode
 * @BSS_CMP_REGULAR: regular compare mode (for insertion and normal find)
 * @BSS_CMP_HIDE_ZLEN: find hidden SSID with zero-length mode
 * @BSS_CMP_HIDE_NUL: find hidden SSID with NUL-ed out mode
 */
enum bss_compare_mode {
        BSS_CMP_REGULAR,
        BSS_CMP_HIDE_ZLEN,
        BSS_CMP_HIDE_NUL,
};

static int cmp_bss(struct cfg80211_bss *a,
                   struct cfg80211_bss *b,
                   enum bss_compare_mode mode)
{
        const struct cfg80211_bss_ies *a_ies, *b_ies;
        const u8 *ie1 = NULL;
        const u8 *ie2 = NULL;
        int i, r;

        if (a->channel != b->channel)
                return b->channel->center_freq - a->channel->center_freq;

        a_ies = rcu_access_pointer(a->ies);
        if (!a_ies)
                return -1;
        b_ies = rcu_access_pointer(b->ies);
        if (!b_ies)
                return 1;

        if (WLAN_CAPABILITY_IS_STA_BSS(a->capability))
                ie1 = cfg80211_find_ie(WLAN_EID_MESH_ID,
                                       a_ies->data, a_ies->len);
        if (WLAN_CAPABILITY_IS_STA_BSS(b->capability))
                ie2 = cfg80211_find_ie(WLAN_EID_MESH_ID,
                                       b_ies->data, b_ies->len);
        if (ie1 && ie2) {
                int mesh_id_cmp;

                if (ie1[1] == ie2[1])
                        mesh_id_cmp = memcmp(ie1 + 2, ie2 + 2, ie1[1]);
                else
                        mesh_id_cmp = ie2[1] - ie1[1];

                ie1 = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
                                       a_ies->data, a_ies->len);
                ie2 = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
                                       b_ies->data, b_ies->len);
                if (ie1 && ie2) {
                        if (mesh_id_cmp)
                                return mesh_id_cmp;
                        if (ie1[1] != ie2[1])
                                return ie2[1] - ie1[1];
                        return memcmp(ie1 + 2, ie2 + 2, ie1[1]);
                }
        }

        /*
         * we can't use compare_ether_addr here since we need a < > operator.
         * The binary return value of compare_ether_addr isn't enough
         */
        r = memcmp(a->bssid, b->bssid, sizeof(a->bssid));
        if (r)
                return r;

        ie1 = cfg80211_find_ie(WLAN_EID_SSID, a_ies->data, a_ies->len);
        ie2 = cfg80211_find_ie(WLAN_EID_SSID, b_ies->data, b_ies->len);

        if (!ie1 && !ie2)
                return 0;

        /*
         * Note that with "hide_ssid", the function returns a match if
         * the already-present BSS ("b") is a hidden SSID beacon for
         * the new BSS ("a").
         */

        /* sort missing IE before (left of) present IE */
        if (!ie1)
                return -1;
        if (!ie2)
                return 1;

        switch (mode) {
        case BSS_CMP_HIDE_ZLEN:
                /*
                 * In ZLEN mode we assume the BSS entry we're
                 * looking for has a zero-length SSID. So if
                 * the one we're looking at right now has that,
                 * return 0. Otherwise, return the difference
                 * in length, but since we're looking for the
                 * 0-length it's really equivalent to returning
                 * the length of the one we're looking at.
                 *
                 * No content comparison is needed as we assume
                 * the content length is zero.
                 */
                return ie2[1];
        case BSS_CMP_REGULAR:
        default:
                /* sort by length first, then by contents */
                if (ie1[1] != ie2[1])
                        return ie2[1] - ie1[1];
                return memcmp(ie1 + 2, ie2 + 2, ie1[1]);
        case BSS_CMP_HIDE_NUL:
                if (ie1[1] != ie2[1])
                        return ie2[1] - ie1[1];
                /* this is equivalent to memcmp(zeroes, ie2 + 2, len) */
                for (i = 0; i < ie2[1]; i++)
                        if (ie2[i + 2])
                                return -1;
                return 0;
        }
}

struct cfg80211_bss *cfg80211_get_bss(struct wiphy *wiphy,
                                      struct ieee80211_channel *channel,
                                      const u8 *bssid,
                                      const u8 *ssid, size_t ssid_len,
                                      u16 capa_mask, u16 capa_val)
{
        struct cfg80211_registered_device *dev = wiphy_to_dev(wiphy);
        struct cfg80211_internal_bss *bss, *res = NULL;
        unsigned long now = jiffies;

        trace_cfg80211_get_bss(wiphy, channel, bssid, ssid, ssid_len, capa_mask,
                               capa_val);

        spin_lock_bh(&dev->bss_lock);

        list_for_each_entry(bss, &dev->bss_list, list) {
                if ((bss->pub.capability & capa_mask) != capa_val)
                        continue;
                if (channel && bss->pub.channel != channel)
                        continue;
                /* Don't get expired BSS structs */
                if (time_after(now, bss->ts + IEEE80211_SCAN_RESULT_EXPIRE) &&
                    !atomic_read(&bss->hold))
                        continue;
                if (is_bss(&bss->pub, bssid, ssid, ssid_len)) {
                        res = bss;
                        bss_ref_get(dev, res);
                        break;
                }
        }

        spin_unlock_bh(&dev->bss_lock);
        if (!res)
                return NULL;
        trace_cfg80211_return_bss(&res->pub);
        return &res->pub;
}
EXPORT_SYMBOL(cfg80211_get_bss);

static void rb_insert_bss(struct cfg80211_registered_device *dev,
                          struct cfg80211_internal_bss *bss)
{
        struct rb_node **p = &dev->bss_tree.rb_node;
        struct rb_node *parent = NULL;
        struct cfg80211_internal_bss *tbss;
        int cmp;

        while (*p) {
                parent = *p;
                tbss = rb_entry(parent, struct cfg80211_internal_bss, rbn);

                cmp = cmp_bss(&bss->pub, &tbss->pub, BSS_CMP_REGULAR);

                if (WARN_ON(!cmp)) {
                        /* will sort of leak this BSS */
                        return;
                }

                if (cmp < 0)
                        p = &(*p)->rb_left;
                else
                        p = &(*p)->rb_right;
        }

        rb_link_node(&bss->rbn, parent, p);
        rb_insert_color(&bss->rbn, &dev->bss_tree);
}

static struct cfg80211_internal_bss *
rb_find_bss(struct cfg80211_registered_device *dev,
            struct cfg80211_internal_bss *res,
            enum bss_compare_mode mode)
{
        struct rb_node *n = dev->bss_tree.rb_node;
        struct cfg80211_internal_bss *bss;
        int r;

        while (n) {
                bss = rb_entry(n, struct cfg80211_internal_bss, rbn);
                r = cmp_bss(&res->pub, &bss->pub, mode);

                if (r == 0)
                        return bss;
                else if (r < 0)
                        n = n->rb_left;
                else
                        n = n->rb_right;
        }

        return NULL;
}

static bool cfg80211_combine_bsses(struct cfg80211_registered_device *dev,
                                   struct cfg80211_internal_bss *new)
{
        const struct cfg80211_bss_ies *ies;
        struct cfg80211_internal_bss *bss;
        const u8 *ie;
        int i, ssidlen;
        u8 fold = 0;

        ies = rcu_access_pointer(new->pub.beacon_ies);
        if (WARN_ON(!ies))
                return false;

        ie = cfg80211_find_ie(WLAN_EID_SSID, ies->data, ies->len);
        if (!ie) {
                /* nothing to do */
                return true;
        }

        ssidlen = ie[1];
        for (i = 0; i < ssidlen; i++)
                fold |= ie[2 + i];

        if (fold) {
                /* not a hidden SSID */
                return true;
        }

        /* This is the bad part ... */

        list_for_each_entry(bss, &dev->bss_list, list) {
                if (!ether_addr_equal(bss->pub.bssid, new->pub.bssid))
                        continue;
                if (bss->pub.channel != new->pub.channel)
                        continue;
                if (rcu_access_pointer(bss->pub.beacon_ies))
                        continue;
                ies = rcu_access_pointer(bss->pub.ies);
                if (!ies)
                        continue;
                ie = cfg80211_find_ie(WLAN_EID_SSID, ies->data, ies->len);
                if (!ie)
                        continue;
                if (ssidlen && ie[1] != ssidlen)
                        continue;
                /* that would be odd ... */
                if (bss->pub.beacon_ies)
                        continue;
                if (WARN_ON_ONCE(bss->pub.hidden_beacon_bss))
                        continue;
                if (WARN_ON_ONCE(!list_empty(&bss->hidden_list)))
                        list_del(&bss->hidden_list);
                /* combine them */
                list_add(&bss->hidden_list, &new->hidden_list);
                bss->pub.hidden_beacon_bss = &new->pub;
                new->refcount += bss->refcount;
                rcu_assign_pointer(bss->pub.beacon_ies,
                                   new->pub.beacon_ies);
        }

        return true;
}

static struct cfg80211_internal_bss *
cfg80211_bss_update(struct cfg80211_registered_device *dev,
                    struct cfg80211_internal_bss *tmp)
{
        struct cfg80211_internal_bss *found = NULL;

        if (WARN_ON(!tmp->pub.channel))
                return NULL;

        tmp->ts = jiffies;

        spin_lock_bh(&dev->bss_lock);

        if (WARN_ON(!rcu_access_pointer(tmp->pub.ies))) {
                spin_unlock_bh(&dev->bss_lock);
                return NULL;
        }

        found = rb_find_bss(dev, tmp, BSS_CMP_REGULAR);

        if (found) {
                /* Update IEs */
                if (rcu_access_pointer(tmp->pub.proberesp_ies)) {
                        const struct cfg80211_bss_ies *old;

                        old = rcu_access_pointer(found->pub.proberesp_ies);

                        rcu_assign_pointer(found->pub.proberesp_ies,
                                           tmp->pub.proberesp_ies);
                        /* Override possible earlier Beacon frame IEs */
                        rcu_assign_pointer(found->pub.ies,
                                           tmp->pub.proberesp_ies);
                        if (old)
                                kfree_rcu((struct cfg80211_bss_ies *)old,
                                          rcu_head);
                } else if (rcu_access_pointer(tmp->pub.beacon_ies)) {
                        const struct cfg80211_bss_ies *old;
                        struct cfg80211_internal_bss *bss;

                        if (found->pub.hidden_beacon_bss &&
                            !list_empty(&found->hidden_list)) {
                                const struct cfg80211_bss_ies *f;

                                /*
                                 * The found BSS struct is one of the probe
                                 * response members of a group, but we're
                                 * receiving a beacon (beacon_ies in the tmp
                                 * bss is used). This can only mean that the
                                 * AP changed its beacon from not having an
                                 * SSID to showing it, which is confusing so
                                 * drop this information.
                                 */

                                f = rcu_access_pointer(tmp->pub.beacon_ies);
                                kfree_rcu((struct cfg80211_bss_ies *)f,
                                          rcu_head);
                                goto drop;
                        }

                        old = rcu_access_pointer(found->pub.beacon_ies);

                        rcu_assign_pointer(found->pub.beacon_ies,
                                           tmp->pub.beacon_ies);

                        /* Override IEs if they were from a beacon before */
                        if (old == rcu_access_pointer(found->pub.ies))
                                rcu_assign_pointer(found->pub.ies,
                                                   tmp->pub.beacon_ies);

                        /* Assign beacon IEs to all sub entries */
                        list_for_each_entry(bss, &found->hidden_list,
                                            hidden_list) {
                                const struct cfg80211_bss_ies *ies;

                                ies = rcu_access_pointer(bss->pub.beacon_ies);
                                WARN_ON(ies != old);

                                rcu_assign_pointer(bss->pub.beacon_ies,
                                                   tmp->pub.beacon_ies);
                        }

                        if (old)
                                kfree_rcu((struct cfg80211_bss_ies *)old,
                                          rcu_head);
                }

                found->pub.beacon_interval = tmp->pub.beacon_interval;
                found->pub.signal = tmp->pub.signal;
                found->pub.capability = tmp->pub.capability;
                found->ts = tmp->ts;
        } else {
                struct cfg80211_internal_bss *new;
                struct cfg80211_internal_bss *hidden;
                struct cfg80211_bss_ies *ies;

                /*
                 * create a copy -- the "res" variable that is passed in
                 * is allocated on the stack since it's not needed in the
                 * more common case of an update
                 */
                new = kzalloc(sizeof(*new) + dev->wiphy.bss_priv_size,
                              GFP_ATOMIC);
                if (!new) {
                        ies = (void *)rcu_dereference(tmp->pub.beacon_ies);
                        if (ies)
                                kfree_rcu(ies, rcu_head);
                        ies = (void *)rcu_dereference(tmp->pub.proberesp_ies);
                        if (ies)
                                kfree_rcu(ies, rcu_head);
                        goto drop;
                }
                memcpy(new, tmp, sizeof(*new));
                new->refcount = 1;
                INIT_LIST_HEAD(&new->hidden_list);

                if (rcu_access_pointer(tmp->pub.proberesp_ies)) {
                        hidden = rb_find_bss(dev, tmp, BSS_CMP_HIDE_ZLEN);
                        if (!hidden)
                                hidden = rb_find_bss(dev, tmp,
                                                     BSS_CMP_HIDE_NUL);
                        if (hidden) {
                                new->pub.hidden_beacon_bss = &hidden->pub;
                                list_add(&new->hidden_list,
                                         &hidden->hidden_list);
                                hidden->refcount++;
                                rcu_assign_pointer(new->pub.beacon_ies,
                                                   hidden->pub.beacon_ies);
                        }
                } else {
                        /*
                         * Ok so we found a beacon, and don't have an entry. If
                         * it's a beacon with hidden SSID, we might be in for an
                         * expensive search for any probe responses that should
                         * be grouped with this beacon for updates ...
                         */
                        if (!cfg80211_combine_bsses(dev, new)) {
                                kfree(new);
                                goto drop;
                        }
                }

                list_add_tail(&new->list, &dev->bss_list);
                rb_insert_bss(dev, new);
                found = new;
        }

        dev->bss_generation++;
        bss_ref_get(dev, found);
        spin_unlock_bh(&dev->bss_lock);

        return found;
 drop:
        spin_unlock_bh(&dev->bss_lock);
        return NULL;
}

static struct ieee80211_channel *
cfg80211_get_bss_channel(struct wiphy *wiphy, const u8 *ie, size_t ielen,
                         struct ieee80211_channel *channel)
{
        const u8 *tmp;
        u32 freq;
        int channel_number = -1;

        tmp = cfg80211_find_ie(WLAN_EID_DS_PARAMS, ie, ielen);
        if (tmp && tmp[1] == 1) {
                channel_number = tmp[2];
        } else {
                tmp = cfg80211_find_ie(WLAN_EID_HT_OPERATION, ie, ielen);
                if (tmp && tmp[1] >= sizeof(struct ieee80211_ht_operation)) {
                        struct ieee80211_ht_operation *htop = (void *)(tmp + 2);

                        channel_number = htop->primary_chan;
                }
        }

        if (channel_number < 0)
                return channel;

        freq = ieee80211_channel_to_frequency(channel_number, channel->band);
        channel = ieee80211_get_channel(wiphy, freq);
        if (!channel)
                return NULL;
        if (channel->flags & IEEE80211_CHAN_DISABLED)
                return NULL;
        return channel;
}

struct cfg80211_bss*
cfg80211_inform_bss(struct wiphy *wiphy,
                    struct ieee80211_channel *channel,
                    const u8 *bssid, u64 tsf, u16 capability,
                    u16 beacon_interval, const u8 *ie, size_t ielen,
                    s32 signal, gfp_t gfp)
{
        struct cfg80211_bss_ies *ies;
        struct cfg80211_internal_bss tmp = {}, *res;

        if (WARN_ON(!wiphy))
                return NULL;

        if (WARN_ON(wiphy->signal_type == CFG80211_SIGNAL_TYPE_UNSPEC &&
                        (signal < 0 || signal > 100)))
                return NULL;

        channel = cfg80211_get_bss_channel(wiphy, ie, ielen, channel);
        if (!channel)
                return NULL;

        memcpy(tmp.pub.bssid, bssid, ETH_ALEN);
        tmp.pub.channel = channel;
        tmp.pub.signal = signal;
        tmp.pub.beacon_interval = beacon_interval;
        tmp.pub.capability = capability;
        /*
         * Since we do not know here whether the IEs are from a Beacon or Probe
         * Response frame, we need to pick one of the options and only use it
         * with the driver that does not provide the full Beacon/Probe Response
         * frame. Use Beacon frame pointer to avoid indicating that this should
         * override the IEs pointer should we have received an earlier
         * indication of Probe Response data.
         */
        ies = kmalloc(sizeof(*ies) + ielen, gfp);
        if (!ies)
                return NULL;
        ies->len = ielen;
        ies->tsf = tsf;
        memcpy(ies->data, ie, ielen);

        rcu_assign_pointer(tmp.pub.beacon_ies, ies);
        rcu_assign_pointer(tmp.pub.ies, ies);

        res = cfg80211_bss_update(wiphy_to_dev(wiphy), &tmp);
        if (!res)
                return NULL;

        if (res->pub.capability & WLAN_CAPABILITY_ESS)
                regulatory_hint_found_beacon(wiphy, channel, gfp);

        trace_cfg80211_return_bss(&res->pub);
        /* cfg80211_bss_update gives us a referenced result */
        return &res->pub;
}
EXPORT_SYMBOL(cfg80211_inform_bss);

struct cfg80211_bss *
cfg80211_inform_bss_frame(struct wiphy *wiphy,
                          struct ieee80211_channel *channel,
                          struct ieee80211_mgmt *mgmt, size_t len,
                          s32 signal, gfp_t gfp)
{
        struct cfg80211_internal_bss tmp = {}, *res;
        struct cfg80211_bss_ies *ies;
        size_t ielen = len - offsetof(struct ieee80211_mgmt,
                                      u.probe_resp.variable);

        BUILD_BUG_ON(offsetof(struct ieee80211_mgmt, u.probe_resp.variable) !=
                        offsetof(struct ieee80211_mgmt, u.beacon.variable));

        trace_cfg80211_inform_bss_frame(wiphy, channel, mgmt, len, signal);

        if (WARN_ON(!mgmt))
                return NULL;

        if (WARN_ON(!wiphy))
                return NULL;

        if (WARN_ON(wiphy->signal_type == CFG80211_SIGNAL_TYPE_UNSPEC &&
                    (signal < 0 || signal > 100)))
                return NULL;

        if (WARN_ON(len < offsetof(struct ieee80211_mgmt, u.probe_resp.variable)))
                return NULL;

        channel = cfg80211_get_bss_channel(wiphy, mgmt->u.beacon.variable,
                                           ielen, channel);
        if (!channel)
                return NULL;

        ies = kmalloc(sizeof(*ies) + ielen, gfp);
        if (!ies)
                return NULL;
        ies->len = ielen;
        ies->tsf = le64_to_cpu(mgmt->u.probe_resp.timestamp);
        memcpy(ies->data, mgmt->u.probe_resp.variable, ielen);

        if (ieee80211_is_probe_resp(mgmt->frame_control))
                rcu_assign_pointer(tmp.pub.proberesp_ies, ies);
        else
                rcu_assign_pointer(tmp.pub.beacon_ies, ies);
        rcu_assign_pointer(tmp.pub.ies, ies);
        
        memcpy(tmp.pub.bssid, mgmt->bssid, ETH_ALEN);
        tmp.pub.channel = channel;
        tmp.pub.signal = signal;
        tmp.pub.beacon_interval = le16_to_cpu(mgmt->u.probe_resp.beacon_int);
        tmp.pub.capability = le16_to_cpu(mgmt->u.probe_resp.capab_info);

        res = cfg80211_bss_update(wiphy_to_dev(wiphy), &tmp);
        if (!res)
                return NULL;

        if (res->pub.capability & WLAN_CAPABILITY_ESS)
                regulatory_hint_found_beacon(wiphy, channel, gfp);

        trace_cfg80211_return_bss(&res->pub);
        /* cfg80211_bss_update gives us a referenced result */
        return &res->pub;
}
EXPORT_SYMBOL(cfg80211_inform_bss_frame);

void cfg80211_ref_bss(struct wiphy *wiphy, struct cfg80211_bss *pub)
{
        struct cfg80211_registered_device *dev = wiphy_to_dev(wiphy);
        struct cfg80211_internal_bss *bss;

        if (!pub)
                return;

        bss = container_of(pub, struct cfg80211_internal_bss, pub);

        spin_lock_bh(&dev->bss_lock);
        bss_ref_get(dev, bss);
        spin_unlock_bh(&dev->bss_lock);
}
EXPORT_SYMBOL(cfg80211_ref_bss);

void cfg80211_put_bss(struct wiphy *wiphy, struct cfg80211_bss *pub)
{
        struct cfg80211_registered_device *dev = wiphy_to_dev(wiphy);
        struct cfg80211_internal_bss *bss;

        if (!pub)
                return;

        bss = container_of(pub, struct cfg80211_internal_bss, pub);

        spin_lock_bh(&dev->bss_lock);
        bss_ref_put(dev, bss);
        spin_unlock_bh(&dev->bss_lock);
}
EXPORT_SYMBOL(cfg80211_put_bss);

void cfg80211_unlink_bss(struct wiphy *wiphy, struct cfg80211_bss *pub)
{
        struct cfg80211_registered_device *dev = wiphy_to_dev(wiphy);
        struct cfg80211_internal_bss *bss;

        if (WARN_ON(!pub))
                return;

        bss = container_of(pub, struct cfg80211_internal_bss, pub);

        spin_lock_bh(&dev->bss_lock);
        if (!list_empty(&bss->list)) {
                if (__cfg80211_unlink_bss(dev, bss))
                        dev->bss_generation++;
        }
        spin_unlock_bh(&dev->bss_lock);
}
EXPORT_SYMBOL(cfg80211_unlink_bss);

#ifdef CONFIG_CFG80211_WEXT
int cfg80211_wext_siwscan(struct net_device *dev,
                          struct iw_request_info *info,
                          union iwreq_data *wrqu, char *extra)
{
        struct cfg80211_registered_device *rdev;
        struct wiphy *wiphy;
        struct iw_scan_req *wreq = NULL;
        struct cfg80211_scan_request *creq = NULL;
        int i, err, n_channels = 0;
        enum ieee80211_band band;

        if (!netif_running(dev))
                return -ENETDOWN;

        if (wrqu->data.length == sizeof(struct iw_scan_req))
                wreq = (struct iw_scan_req *)extra;

        rdev = cfg80211_get_dev_from_ifindex(dev_net(dev), dev->ifindex);

        if (IS_ERR(rdev))
                return PTR_ERR(rdev);

        mutex_lock(&rdev->sched_scan_mtx);
        if (rdev->scan_req) {
                err = -EBUSY;
                goto out;
        }

        wiphy = &rdev->wiphy;

        /* Determine number of channels, needed to allocate creq */
        if (wreq && wreq->num_channels)
                n_channels = wreq->num_channels;
        else {
                for (band = 0; band < IEEE80211_NUM_BANDS; band++)
                        if (wiphy->bands[band])
                                n_channels += wiphy->bands[band]->n_channels;
        }

        creq = kzalloc(sizeof(*creq) + sizeof(struct cfg80211_ssid) +
                       n_channels * sizeof(void *),
                       GFP_ATOMIC);
        if (!creq) {
                err = -ENOMEM;
                goto out;
        }

        creq->wiphy = wiphy;
        creq->wdev = dev->ieee80211_ptr;
        /* SSIDs come after channels */
        creq->ssids = (void *)&creq->channels[n_channels];
        creq->n_channels = n_channels;
        creq->n_ssids = 1;
        creq->scan_start = jiffies;

        /* translate "Scan on frequencies" request */
        i = 0;
        for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
                int j;

                if (!wiphy->bands[band])
                        continue;

                for (j = 0; j < wiphy->bands[band]->n_channels; j++) {
                        /* ignore disabled channels */
                        if (wiphy->bands[band]->channels[j].flags &
                                                IEEE80211_CHAN_DISABLED)
                                continue;

                        /* If we have a wireless request structure and the
                         * wireless request specifies frequencies, then search
                         * for the matching hardware channel.
                         */
                        if (wreq && wreq->num_channels) {
                                int k;
                                int wiphy_freq = wiphy->bands[band]->channels[j].center_freq;
                                for (k = 0; k < wreq->num_channels; k++) {
                                        int wext_freq = cfg80211_wext_freq(wiphy, &wreq->channel_list[k]);
                                        if (wext_freq == wiphy_freq)
                                                goto wext_freq_found;
                                }
                                goto wext_freq_not_found;
                        }

                wext_freq_found:
                        creq->channels[i] = &wiphy->bands[band]->channels[j];
                        i++;
                wext_freq_not_found: ;
                }
        }
        /* No channels found? */
        if (!i) {
                err = -EINVAL;
                goto out;
        }

        /* Set real number of channels specified in creq->channels[] */
        creq->n_channels = i;

        /* translate "Scan for SSID" request */
        if (wreq) {
                if (wrqu->data.flags & IW_SCAN_THIS_ESSID) {
                        if (wreq->essid_len > IEEE80211_MAX_SSID_LEN) {
                                err = -EINVAL;
                                goto out;
                        }
                        memcpy(creq->ssids[0].ssid, wreq->essid, wreq->essid_len);
                        creq->ssids[0].ssid_len = wreq->essid_len;
                }
                if (wreq->scan_type == IW_SCAN_TYPE_PASSIVE)
                        creq->n_ssids = 0;
        }

        for (i = 0; i < IEEE80211_NUM_BANDS; i++)
                if (wiphy->bands[i])
                        creq->rates[i] = (1 << wiphy->bands[i]->n_bitrates) - 1;

        rdev->scan_req = creq;
        err = rdev_scan(rdev, creq);
        if (err) {
                rdev->scan_req = NULL;
                /* creq will be freed below */
        } else {
                nl80211_send_scan_start(rdev, dev->ieee80211_ptr);
                /* creq now owned by driver */
                creq = NULL;
                dev_hold(dev);
        }
 out:
        mutex_unlock(&rdev->sched_scan_mtx);
        kfree(creq);
        cfg80211_unlock_rdev(rdev);
        return err;
}
EXPORT_SYMBOL_GPL(cfg80211_wext_siwscan);

static void ieee80211_scan_add_ies(struct iw_request_info *info,
                                   const struct cfg80211_bss_ies *ies,
                                   char **current_ev, char *end_buf)
{
        const u8 *pos, *end, *next;
        struct iw_event iwe;

        if (!ies)
                return;

        /*
         * If needed, fragment the IEs buffer (at IE boundaries) into short
         * enough fragments to fit into IW_GENERIC_IE_MAX octet messages.
         */
        pos = ies->data;
        end = pos + ies->len;

        while (end - pos > IW_GENERIC_IE_MAX) {
                next = pos + 2 + pos[1];
                while (next + 2 + next[1] - pos < IW_GENERIC_IE_MAX)
                        next = next + 2 + next[1];

                memset(&iwe, 0, sizeof(iwe));
                iwe.cmd = IWEVGENIE;
                iwe.u.data.length = next - pos;
                *current_ev = iwe_stream_add_point(info, *current_ev,
                                                   end_buf, &iwe,
                                                   (void *)pos);

                pos = next;
        }

        if (end > pos) {
                memset(&iwe, 0, sizeof(iwe));
                iwe.cmd = IWEVGENIE;
                iwe.u.data.length = end - pos;
                *current_ev = iwe_stream_add_point(info, *current_ev,
                                                   end_buf, &iwe,
                                                   (void *)pos);
        }
}

static char *
ieee80211_bss(struct wiphy *wiphy, struct iw_request_info *info,
              struct cfg80211_internal_bss *bss, char *current_ev,
              char *end_buf)
{
        const struct cfg80211_bss_ies *ies;
        struct iw_event iwe;
        const u8 *ie;
        u8 *buf, *cfg, *p;
        int rem, i, sig;
        bool ismesh = false;

        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = SIOCGIWAP;
        iwe.u.ap_addr.sa_family = ARPHRD_ETHER;
        memcpy(iwe.u.ap_addr.sa_data, bss->pub.bssid, ETH_ALEN);
        current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
                                          IW_EV_ADDR_LEN);

        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = SIOCGIWFREQ;
        iwe.u.freq.m = ieee80211_frequency_to_channel(bss->pub.channel->center_freq);
        iwe.u.freq.e = 0;
        current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
                                          IW_EV_FREQ_LEN);

        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = SIOCGIWFREQ;
        iwe.u.freq.m = bss->pub.channel->center_freq;
        iwe.u.freq.e = 6;
        current_ev = iwe_stream_add_event(info, current_ev, end_buf, &iwe,
                                          IW_EV_FREQ_LEN);

        if (wiphy->signal_type != CFG80211_SIGNAL_TYPE_NONE) {
                memset(&iwe, 0, sizeof(iwe));
                iwe.cmd = IWEVQUAL;
                iwe.u.qual.updated = IW_QUAL_LEVEL_UPDATED |
                                     IW_QUAL_NOISE_INVALID |
                                     IW_QUAL_QUAL_UPDATED;
                switch (wiphy->signal_type) {
                case CFG80211_SIGNAL_TYPE_MBM:
                        sig = bss->pub.signal / 100;
                        iwe.u.qual.level = sig;
                        iwe.u.qual.updated |= IW_QUAL_DBM;
                        if (sig < -110)         /* rather bad */
                                sig = -110;
                        else if (sig > -40)     /* perfect */
                                sig = -40;
                        /* will give a range of 0 .. 70 */
                        iwe.u.qual.qual = sig + 110;
                        break;
                case CFG80211_SIGNAL_TYPE_UNSPEC:
                        iwe.u.qual.level = bss->pub.signal;
                        /* will give range 0 .. 100 */
                        iwe.u.qual.qual = bss->pub.signal;
                        break;
                default:
                        /* not reached */
                        break;
                }
                current_ev = iwe_stream_add_event(info, current_ev, end_buf,
                                                  &iwe, IW_EV_QUAL_LEN);
        }

        memset(&iwe, 0, sizeof(iwe));
        iwe.cmd = SIOCGIWENCODE;
        if (bss->pub.capability & WLAN_CAPABILITY_PRIVACY)
                iwe.u.data.flags = IW_ENCODE_ENABLED | IW_ENCODE_NOKEY;
        else
                iwe.u.data.flags = IW_ENCODE_DISABLED;
        iwe.u.data.length = 0;
        current_ev = iwe_stream_add_point(info, current_ev, end_buf,
                                          &iwe, "");

        rcu_read_lock();
        ies = rcu_dereference(bss->pub.ies);
        rem = ies->len;
        ie = ies->data;

        while (rem >= 2) {
                /* invalid data */
                if (ie[1] > rem - 2)
                        break;

                switch (ie[0]) {
                case WLAN_EID_SSID:
                        memset(&iwe, 0, sizeof(iwe));
                        iwe.cmd = SIOCGIWESSID;
                        iwe.u.data.length = ie[1];
                        iwe.u.data.flags = 1;
                        current_ev = iwe_stream_add_point(info, current_ev, end_buf,
                                                          &iwe, (u8 *)ie + 2);
                        break;
                case WLAN_EID_MESH_ID:
                        memset(&iwe, 0, sizeof(iwe));
                        iwe.cmd = SIOCGIWESSID;
                        iwe.u.data.length = ie[1];
                        iwe.u.data.flags = 1;
                        current_ev = iwe_stream_add_point(info, current_ev, end_buf,
                                                          &iwe, (u8 *)ie + 2);
                        break;
                case WLAN_EID_MESH_CONFIG:
                        ismesh = true;
                        if (ie[1] != sizeof(struct ieee80211_meshconf_ie))
                                break;
                        buf = kmalloc(50, GFP_ATOMIC);
                        if (!buf)
                                break;
                        cfg = (u8 *)ie + 2;
                        memset(&iwe, 0, sizeof(iwe));
                        iwe.cmd = IWEVCUSTOM;
                        sprintf(buf, "Mesh Network Path Selection Protocol ID: "
                                "0x%02X", cfg[0]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Path Selection Metric ID: 0x%02X",
                                cfg[1]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Congestion Control Mode ID: 0x%02X",
                                cfg[2]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Synchronization ID: 0x%02X", cfg[3]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Authentication ID: 0x%02X", cfg[4]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Formation Info: 0x%02X", cfg[5]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        sprintf(buf, "Capabilities: 0x%02X", cfg[6]);
                        iwe.u.data.length = strlen(buf);
                        current_ev = iwe_stream_add_point(info, current_ev,
                                                          end_buf,
                                                          &iwe, buf);
                        kfree(buf);
                        break;
                case WLAN_EID_SUPP_RATES:
                case WLAN_EID_EXT_SUPP_RATES:
                        /* display all supported rates in readable format */
                        p = current_ev + iwe_stream_lcp_len(info);

                        memset(&iwe, 0, sizeof(iwe));
                        iwe.cmd = SIOCGIWRATE;
                        /* Those two flags are ignored... */
                        iwe.u.bitrate.fixed = iwe.u.bitrate.disabled = 0;

                        for (i = 0; i < ie[1]; i++) {
                                iwe.u.bitrate.value =
                                        ((ie[i + 2] & 0x7f) * 500000);
                                p = iwe_stream_add_value(info, current_ev, p,
                                                end_buf, &iwe, IW_EV_PARAM_LEN);
                        }
                        current_ev = p;
                        break;
                }
                rem -= ie[1] + 2;
                ie += ie[1] + 2;
        }

        if (bss->pub.capability & (WLAN_CAPABILITY_ESS | WLAN_CAPABILITY_IBSS) ||
            ismesh) {
                memset(&iwe, 0, sizeof(iwe));
                iwe.cmd = SIOCGIWMODE;
                if (ismesh)
                        iwe.u.mode = IW_MODE_MESH;
                else if (bss->pub.capability & WLAN_CAPABILITY_ESS)
                        iwe.u.mode = IW_MODE_MASTER;
                else
                        iwe.u.mode = IW_MODE_ADHOC;
                current_ev = iwe_stream_add_event(info, current_ev, end_buf,
                                                  &iwe, IW_EV_UINT_LEN);
        }

        buf = kmalloc(31, GFP_ATOMIC);
        if (buf) {
                memset(&iwe, 0, sizeof(iwe));
                iwe.cmd = IWEVCUSTOM;
                sprintf(buf, "tsf=%016llx", (unsigned long long)(ies->tsf));
                iwe.u.data.length = strlen(buf);
                current_ev = iwe_stream_add_point(info, current_ev, end_buf,
                                                  &iwe, buf);
                memset(&iwe, 0, sizeof(iwe));
                iwe.cmd = IWEVCUSTOM;
                sprintf(buf, " Last beacon: %ums ago",
                        elapsed_jiffies_msecs(bss->ts));
                iwe.u.data.length = strlen(buf);
                current_ev = iwe_stream_add_point(info, current_ev,
                                                  end_buf, &iwe, buf);
                kfree(buf);
        }

        ieee80211_scan_add_ies(info, ies, &current_ev, end_buf);
        rcu_read_unlock();

        return current_ev;
}


static int ieee80211_scan_results(struct cfg80211_registered_device *dev,
                                  struct iw_request_info *info,
                                  char *buf, size_t len)
{
        char *current_ev = buf;
        char *end_buf = buf + len;
        struct cfg80211_internal_bss *bss;

        spin_lock_bh(&dev->bss_lock);
        cfg80211_bss_expire(dev);

        list_for_each_entry(bss, &dev->bss_list, list) {
                if (buf + len - current_ev <= IW_EV_ADDR_LEN) {
                        spin_unlock_bh(&dev->bss_lock);
                        return -E2BIG;
                }
                current_ev = ieee80211_bss(&dev->wiphy, info, bss,
                                           current_ev, end_buf);
        }
        spin_unlock_bh(&dev->bss_lock);
        return current_ev - buf;
}


int cfg80211_wext_giwscan(struct net_device *dev,
                          struct iw_request_info *info,
                          struct iw_point *data, char *extra)
{
        struct cfg80211_registered_device *rdev;
        int res;

        if (!netif_running(dev))
                return -ENETDOWN;

        rdev = cfg80211_get_dev_from_ifindex(dev_net(dev), dev->ifindex);

        if (IS_ERR(rdev))
                return PTR_ERR(rdev);

        if (rdev->scan_req) {
                res = -EAGAIN;
                goto out;
        }

        res = ieee80211_scan_results(rdev, info, extra, data->length);
        data->length = 0;
        if (res >= 0) {
                data->length = res;
                res = 0;
        }

 out:
        cfg80211_unlock_rdev(rdev);
        return res;
}
EXPORT_SYMBOL_GPL(cfg80211_wext_giwscan);
#endif