mac80211: sparse RCU annotations

This adds sparse RCU annotations to most of
mac80211, only the mesh code remains to be
done.

Due the the previous patches, the annotations
are pretty simple. The only thing that this
actually changes is removing the RCU usage of
key->sta in debugfs since this pointer isn't
actually an RCU-managed pointer (it only has
a single assignment done before the key even
goes live). As that is otherwise harmless, I
decided to make it part of this patch.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 17 insertions, 3 deletions

diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index 2aec7c4f357b..2b18053070c1 100644
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -560,6 +560,14 @@ static void hwmp_preq_frame_process(struct ieee80211_sub_if_data *sdata,
 }
 
 
+static inline struct sta_info *
+next_hop_deref_protected(struct mesh_path *mpath)
+{
+        return rcu_dereference_protected(mpath->next_hop,
+                                         lockdep_is_held(&mpath->state_lock));
+}
+
+
 static void hwmp_prep_frame_process(struct ieee80211_sub_if_data *sdata,
                                     struct ieee80211_mgmt *mgmt,
                                     u8 *prep_elem, u32 metric)
@@ -599,7 +607,7 @@ static void hwmp_prep_frame_process(struct ieee80211_sub_if_data *sdata,
                 spin_unlock_bh(&mpath->state_lock);
                 goto fail;
         }
-        memcpy(next_hop, mpath->next_hop->sta.addr, ETH_ALEN);
+        memcpy(next_hop, next_hop_deref_protected(mpath)->sta.addr, ETH_ALEN);
         spin_unlock_bh(&mpath->state_lock);
         --ttl;
         flags = PREP_IE_FLAGS(prep_elem);
@@ -651,7 +659,8 @@ static void hwmp_perr_frame_process(struct ieee80211_sub_if_data *sdata,
         if (mpath) {
                 spin_lock_bh(&mpath->state_lock);
                 if (mpath->flags & MESH_PATH_ACTIVE &&
-                    memcmp(ta, mpath->next_hop->sta.addr, ETH_ALEN) == 0 &&
+                    memcmp(ta, next_hop_deref_protected(mpath)->sta.addr,
+                                                        ETH_ALEN) == 0 &&
                     (!(mpath->flags & MESH_PATH_SN_VALID) ||
                     SN_GT(target_sn, mpath->sn))) {
                         mpath->flags &= ~MESH_PATH_ACTIVE;
@@ -913,6 +922,7 @@ int mesh_nexthop_lookup(struct sk_buff *skb,
 {
         struct sk_buff *skb_to_free = NULL;
         struct mesh_path *mpath;
+        struct sta_info *next_hop;
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
         u8 *target_addr = hdr->addr3;
         int err = 0;
@@ -940,7 +950,11 @@ int mesh_nexthop_lookup(struct sk_buff *skb,
                         mesh_queue_preq(mpath,
                                         PREQ_Q_F_START | PREQ_Q_F_REFRESH);
                 }
-                memcpy(hdr->addr1, mpath->next_hop->sta.addr, ETH_ALEN);
+                next_hop = rcu_dereference(mpath->next_hop);
+                if (next_hop)
+                        memcpy(hdr->addr1, next_hop->sta.addr, ETH_ALEN);
+                else
+                        err = -ENOENT;
         } else {
                 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
                 if (!(mpath->flags & MESH_PATH_RESOLVING)) {