cfg80211: Properly track transmitting and non-transmitting BSS

When holding data of the non-transmitting BSS, we need to keep the
transmitting BSS data on. Otherwise it will be released, and release
the non-transmitting BSS with it.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 46 insertions, 2 deletions

diff --git a/net/wireless/core.h b/net/wireless/core.h
index a50b92ac77a1..c20c75df60f5 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -153,6 +153,7 @@ struct cfg80211_internal_bss {
         struct list_head list;
         struct list_head hidden_list;
         struct list_head nontrans_list;
+        struct cfg80211_bss *transmitted_bss;
         struct rb_node rbn;
         u64 ts_boottime;
         unsigned long ts;
@@ -183,12 +184,23 @@ static inline struct cfg80211_internal_bss *bss_from_pub(struct cfg80211_bss *pu
 static inline void cfg80211_hold_bss(struct cfg80211_internal_bss *bss)
 {
         atomic_inc(&bss->hold);
+        if (bss->transmitted_bss) {
+                bss = container_of(bss->transmitted_bss,
+                                   struct cfg80211_internal_bss, pub);
+                atomic_inc(&bss->hold);
+        }
 }
 
 static inline void cfg80211_unhold_bss(struct cfg80211_internal_bss *bss)
 {
         int r = atomic_dec_return(&bss->hold);
         WARN_ON(r < 0);
+        if (bss->transmitted_bss) {
+                bss = container_of(bss->transmitted_bss,
+                                   struct cfg80211_internal_bss, pub);
+                r = atomic_dec_return(&bss->hold);
+                WARN_ON(r < 0);
+        }
 }
 
 
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 54feb7741c26..d5950a23e619 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -110,6 +110,12 @@ static inline void bss_ref_get(struct cfg80211_registered_device *rdev,
                                    pub);
                 bss->refcount++;
         }
+        if (bss->transmitted_bss) {
+                bss = container_of(bss->transmitted_bss,
+                                   struct cfg80211_internal_bss,
+                                   pub);
+                bss->refcount++;
+        }
 }
 
 static inline void bss_ref_put(struct cfg80211_registered_device *rdev,
@@ -126,6 +132,18 @@ static inline void bss_ref_put(struct cfg80211_registered_device *rdev,
                 if (hbss->refcount == 0)
                         bss_free(hbss);
         }
+
+        if (bss->transmitted_bss) {
+                struct cfg80211_internal_bss *tbss;
+
+                tbss = container_of(bss->transmitted_bss,
+                                    struct cfg80211_internal_bss,
+                                    pub);
+                tbss->refcount--;
+                if (tbss->refcount == 0)
+                        bss_free(tbss);
+        }
+
         bss->refcount--;
         if (bss->refcount == 0)
                 bss_free(bss);
@@ -1024,6 +1042,7 @@ static bool cfg80211_combine_bsses(struct cfg80211_registered_device *rdev,
 static struct cfg80211_internal_bss *
 cfg80211_bss_update(struct cfg80211_registered_device *rdev,
                     struct cfg80211_internal_bss *tmp,
+                    struct cfg80211_bss *trans_bss,
                     bool signal_valid)
 {
         struct cfg80211_internal_bss *found = NULL;
@@ -1181,6 +1200,17 @@ cfg80211_bss_update(struct cfg80211_registered_device *rdev,
                         goto drop;
                 }
 
+                /* This must be before the call to bss_ref_get */
+                if (trans_bss) {
+                        struct cfg80211_internal_bss *pbss =
+                                container_of(trans_bss,
+                                             struct cfg80211_internal_bss,
+                                             pub);
+
+                        new->transmitted_bss = trans_bss;
+                        bss_ref_get(rdev, pbss);
+                }
+
                 list_add_tail(&new->list, &rdev->bss_list);
                 rdev->bss_entries++;
                 rb_insert_bss(rdev, new);
@@ -1336,7 +1366,8 @@ cfg80211_inform_single_bss_data(struct wiphy *wiphy,
 
         signal_valid = abs(data->chan->center_freq - channel->center_freq) <=
                 wiphy->max_adj_channel_rssi_comp;
-        res = cfg80211_bss_update(wiphy_to_rdev(wiphy), &tmp, signal_valid);
+        res = cfg80211_bss_update(wiphy_to_rdev(wiphy), &tmp, trans_bss,
+                                  signal_valid);
         if (!res)
                 return NULL;
 
@@ -1639,7 +1670,8 @@ cfg80211_inform_single_bss_frame_data(struct wiphy *wiphy,
 
         signal_valid = abs(data->chan->center_freq - channel->center_freq) <=
                 wiphy->max_adj_channel_rssi_comp;
-        res = cfg80211_bss_update(wiphy_to_rdev(wiphy), &tmp, signal_valid);
+        res = cfg80211_bss_update(wiphy_to_rdev(wiphy), &tmp, trans_bss,
+                                  signal_valid);
         if (!res)
                 return NULL;