cfg80211: refactor hidden SSID finding

Instead of duplicating the rbtree functions, pass
an argument to the compare function. This removes
the code duplication for the two searches.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 20 insertions, 62 deletions

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index ca367c58a3e2..cfc4e1aa8dad 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -425,34 +425,13 @@ static int cmp_bss_core(struct cfg80211_bss *a, struct cfg80211_bss *b)
 }
 
 static int cmp_bss(struct cfg80211_bss *a,
-                   struct cfg80211_bss *b)
-{
-        const struct cfg80211_bss_ies *a_ies, *b_ies;
-        int r;
-
-        r = cmp_bss_core(a, b);
-        if (r)
-                return r;
-
-        a_ies = rcu_access_pointer(a->ies);
-        if (!a_ies)
-                return -1;
-        b_ies = rcu_access_pointer(b->ies);
-        if (!b_ies)
-                return 1;
-
-        return cmp_ies(WLAN_EID_SSID,
-                       a_ies->data, a_ies->len,
-                       b_ies->data, b_ies->len);
-}
-
-static int cmp_hidden_bss(struct cfg80211_bss *a, struct cfg80211_bss *b)
+                   struct cfg80211_bss *b,
+                   bool hide_ssid)
 {
         const struct cfg80211_bss_ies *a_ies, *b_ies;
         const u8 *ie1;
         const u8 *ie2;
-        int i;
-        int r;
+        int i, r;
 
         r = cmp_bss_core(a, b);
         if (r)
@@ -468,15 +447,13 @@ static int cmp_hidden_bss(struct cfg80211_bss *a, struct cfg80211_bss *b)
         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;
+
         /*
-         * Key comparator must use same algorithm in any rb-tree
-         * search function (order is important), otherwise ordering
-         * of items in the tree is broken and search gives incorrect
-         * results. This code uses same order as cmp_ies() does.
-         *
-         * Note that due to the differring behaviour with hidden SSIDs
-         * this function only works when "b" is the tree element and
-         * "a" is the key we're looking for.
+         * 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 */
@@ -485,14 +462,17 @@ static int cmp_hidden_bss(struct cfg80211_bss *a, struct cfg80211_bss *b)
         if (!ie2)
                 return 1;
 
-        /* zero-size SSID is used as an indication of the hidden bss */
-        if (!ie2[1])
+        /* zero-length SSID is used as an indication of the hidden bss */
+        if (hide_ssid && !ie2[1])
                 return 0;
 
         /* sort by length first, then by contents */
         if (ie1[1] != ie2[1])
                 return ie2[1] - ie1[1];
 
+        if (!hide_ssid)
+                return memcmp(ie1 + 2, ie2 + 2, ie1[1]);
+
         /*
          * zeroed SSID ie is another indication of a hidden bss;
          * if it isn't zeroed just return the regular sort value
@@ -584,7 +564,7 @@ static void rb_insert_bss(struct cfg80211_registered_device *dev,
                 parent = *p;
                 tbss = rb_entry(parent, struct cfg80211_internal_bss, rbn);
 
-                cmp = cmp_bss(&bss->pub, &tbss->pub);
+                cmp = cmp_bss(&bss->pub, &tbss->pub, false);
 
                 if (WARN_ON(!cmp)) {
                         /* will sort of leak this BSS */
@@ -603,30 +583,8 @@ static void rb_insert_bss(struct cfg80211_registered_device *dev,
 
 static struct cfg80211_internal_bss *
 rb_find_bss(struct cfg80211_registered_device *dev,
-            struct cfg80211_internal_bss *res)
-{
-        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);
-
-                if (r == 0)
-                        return bss;
-                else if (r < 0)
-                        n = n->rb_left;
-                else
-                        n = n->rb_right;
-        }
-
-        return NULL;
-}
-
-static struct cfg80211_internal_bss *
-rb_find_hidden_bss(struct cfg80211_registered_device *dev,
-                   struct cfg80211_internal_bss *res)
+            struct cfg80211_internal_bss *res,
+            bool hidden)
 {
         struct rb_node *n = dev->bss_tree.rb_node;
         struct cfg80211_internal_bss *bss;
@@ -634,7 +592,7 @@ rb_find_hidden_bss(struct cfg80211_registered_device *dev,
 
         while (n) {
                 bss = rb_entry(n, struct cfg80211_internal_bss, rbn);
-                r = cmp_hidden_bss(&res->pub, &bss->pub);
+                r = cmp_bss(&res->pub, &bss->pub, hidden);
 
                 if (r == 0)
                         return bss;
@@ -684,7 +642,7 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev,
                 return NULL;
         }
 
-        found = rb_find_bss(dev, tmp);
+        found = rb_find_bss(dev, tmp, false);
 
         if (found) {
                 found->pub.beacon_interval = tmp->pub.beacon_interval;
@@ -739,7 +697,7 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev,
                 /* TODO: The code is not trying to update existing probe
                  * response bss entries when beacon ies are
                  * getting changed. */
-                hidden = rb_find_hidden_bss(dev, tmp);
+                hidden = rb_find_bss(dev, tmp, true);
                 if (hidden)
                         copy_hidden_ies(tmp, hidden);