mac80211: avoid scheduling while atomic in mesh_rx_plink_frame

While mesh_rx_plink_frame holds sta->lock...

mesh_rx_plink_frame ->
	mesh_plink_inc_estab_count ->
		ieee80211_bss_info_change_notify

...but ieee80211_bss_info_change_notify is allowed to sleep.  A driver
taking advantage of that allowance can cause a scheduling while
atomic bug.  Similar paths exist for mesh_plink_dec_estab_count,
so work around those as well.

http://bugzilla.kernel.org/show_bug.cgi?id=16099

Also, correct a minor kerneldoc comment error (mismatched function names).

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Cc: stable@kernel.org

1 files changed, 31 insertions, 11 deletions

diff --git a/net/mac80211/mesh_plink.c b/net/mac80211/mesh_plink.c
index 3cd5f7b5d693..ea13a80a476c 100644
--- a/net/mac80211/mesh_plink.c
+++ b/net/mac80211/mesh_plink.c
@@ -65,7 +65,6 @@ void mesh_plink_inc_estab_count(struct ieee80211_sub_if_data *sdata)
 {
         atomic_inc(&sdata->u.mesh.mshstats.estab_plinks);
         mesh_accept_plinks_update(sdata);
-        ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
 }
 
 static inline
@@ -73,7 +72,6 @@ void mesh_plink_dec_estab_count(struct ieee80211_sub_if_data *sdata)
 {
         atomic_dec(&sdata->u.mesh.mshstats.estab_plinks);
         mesh_accept_plinks_update(sdata);
-        ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
 }
 
 /**
@@ -115,7 +113,7 @@ static struct sta_info *mesh_plink_alloc(struct ieee80211_sub_if_data *sdata,
 }
 
 /**
- * mesh_plink_deactivate - deactivate mesh peer link
+ * __mesh_plink_deactivate - deactivate mesh peer link
  *
  * @sta: mesh peer link to deactivate
  *
@@ -123,18 +121,23 @@ static struct sta_info *mesh_plink_alloc(struct ieee80211_sub_if_data *sdata,
  *
  * Locking: the caller must hold sta->lock
  */
-static void __mesh_plink_deactivate(struct sta_info *sta)
+static bool __mesh_plink_deactivate(struct sta_info *sta)
 {
         struct ieee80211_sub_if_data *sdata = sta->sdata;
+        bool deactivated = false;
 
-        if (sta->plink_state == PLINK_ESTAB)
+        if (sta->plink_state == PLINK_ESTAB) {
                 mesh_plink_dec_estab_count(sdata);
+                deactivated = true;
+        }
         sta->plink_state = PLINK_BLOCKED;
         mesh_path_flush_by_nexthop(sta);
+
+        return deactivated;
 }
 
 /**
- * __mesh_plink_deactivate - deactivate mesh peer link
+ * mesh_plink_deactivate - deactivate mesh peer link
  *
  * @sta: mesh peer link to deactivate
  *
@@ -142,9 +145,15 @@ static void __mesh_plink_deactivate(struct sta_info *sta)
  */
 void mesh_plink_deactivate(struct sta_info *sta)
 {
+        struct ieee80211_sub_if_data *sdata = sta->sdata;
+        bool deactivated;
+
         spin_lock_bh(&sta->lock);
-        __mesh_plink_deactivate(sta);
+        deactivated = __mesh_plink_deactivate(sta);
         spin_unlock_bh(&sta->lock);
+
+        if (deactivated)
+                ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
 }
 
 static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
@@ -381,10 +390,16 @@ int mesh_plink_open(struct sta_info *sta)
 
 void mesh_plink_block(struct sta_info *sta)
 {
+        struct ieee80211_sub_if_data *sdata = sta->sdata;
+        bool deactivated;
+
         spin_lock_bh(&sta->lock);
-        __mesh_plink_deactivate(sta);
+        deactivated = __mesh_plink_deactivate(sta);
         sta->plink_state = PLINK_BLOCKED;
         spin_unlock_bh(&sta->lock);
+
+        if (deactivated)
+                ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
 }
 
 
@@ -397,6 +412,7 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
         enum plink_event event;
         enum plink_frame_type ftype;
         size_t baselen;
+        bool deactivated;
         u8 ie_len;
         u8 *baseaddr;
         __le16 plid, llid, reason;
@@ -651,8 +667,9 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
                 case CNF_ACPT:
                         del_timer(&sta->plink_timer);
                         sta->plink_state = PLINK_ESTAB;
-                        mesh_plink_inc_estab_count(sdata);
                         spin_unlock_bh(&sta->lock);
+                        mesh_plink_inc_estab_count(sdata);
+                        ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
                         mpl_dbg("Mesh plink with %pM ESTABLISHED\n",
                                 sta->sta.addr);
                         break;
@@ -684,8 +701,9 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
                 case OPN_ACPT:
                         del_timer(&sta->plink_timer);
                         sta->plink_state = PLINK_ESTAB;
-                        mesh_plink_inc_estab_count(sdata);
                         spin_unlock_bh(&sta->lock);
+                        mesh_plink_inc_estab_count(sdata);
+                        ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
                         mpl_dbg("Mesh plink with %pM ESTABLISHED\n",
                                 sta->sta.addr);
                         mesh_plink_frame_tx(sdata, PLINK_CONFIRM, sta->sta.addr, llid,
@@ -702,11 +720,13 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
                 case CLS_ACPT:
                         reason = cpu_to_le16(MESH_CLOSE_RCVD);
                         sta->reason = reason;
-                        __mesh_plink_deactivate(sta);
+                        deactivated = __mesh_plink_deactivate(sta);
                         sta->plink_state = PLINK_HOLDING;
                         llid = sta->llid;
                         mod_plink_timer(sta, dot11MeshHoldingTimeout(sdata));
                         spin_unlock_bh(&sta->lock);
+                        if (deactivated)
+                                ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
                         mesh_plink_frame_tx(sdata, PLINK_CLOSE, sta->sta.addr, llid,
                                             plid, reason);
                         break;