wifi: mac80211: reduce iflist_mtx

We now hold the wiphy mutex everywhere that we use or
needed the iflist_mtx, so we don't need this mutex any
more in mac80211. However, drivers may also iterate,
and in some cases (e.g. mt76) do so from high-priority
contexts. Thus, keep the mutex around but remove its
usage in mac80211 apart from those driver-visible parts
that are still needed.

Most of this change was done automatically with spatch,
with the parts that are still needed as described above
reverted manually.

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

1 files changed, 12 insertions, 16 deletions

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 9724a3d4545b..f7f58c3e8349 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -33,14 +33,13 @@
  * The interface list in each struct ieee80211_local is protected
  * three-fold:
  *
- * (1) modifications may only be done under the RTNL
- * (2) modifications and readers are protected against each other by
- *     the iflist_mtx.
- * (3) modifications are done in an RCU manner so atomic readers
+ * (1) modifications may only be done under the RTNL *and* wiphy mutex
+ *     *and* iflist_mtx
+ * (2) modifications are done in an RCU manner so atomic readers
  *     can traverse the list in RCU-safe blocks.
  *
  * As a consequence, reads (traversals) of the list can be protected
- * by either the RTNL, the iflist_mtx or RCU.
+ * by either the RTNL, the wiphy mutex, the iflist_mtx or RCU.
  */
 
 static void ieee80211_iface_work(struct wiphy *wiphy, struct wiphy_work *work);
@@ -160,6 +159,8 @@ static int ieee80211_verify_mac(struct ieee80211_sub_if_data *sdata, u8 *addr,
 	u8 *m;
 	int ret = 0;
 
+	lockdep_assert_wiphy(local->hw.wiphy);
+
 	if (is_zero_ether_addr(local->hw.wiphy->addr_mask))
 		return 0;
 
@@ -176,7 +177,6 @@ static int ieee80211_verify_mac(struct ieee80211_sub_if_data *sdata, u8 *addr,
 	if (!check_dup)
 		return ret;
 
-	mutex_lock(&local->iflist_mtx);
 	list_for_each_entry(iter, &local->interfaces, list) {
 		if (iter == sdata)
 			continue;
@@ -195,7 +195,6 @@ static int ieee80211_verify_mac(struct ieee80211_sub_if_data *sdata, u8 *addr,
 			break;
 		}
 	}
-	mutex_unlock(&local->iflist_mtx);
 
 	return ret;
 }
@@ -1049,7 +1048,7 @@ void ieee80211_recalc_offload(struct ieee80211_local *local)
 	if (!ieee80211_hw_check(&local->hw, SUPPORTS_TX_ENCAP_OFFLOAD))
 		return;
 
-	mutex_lock(&local->iflist_mtx);
+	lockdep_assert_wiphy(local->hw.wiphy);
 
 	list_for_each_entry(sdata, &local->interfaces, list) {
 		if (!ieee80211_sdata_running(sdata))
@@ -1057,8 +1056,6 @@ void ieee80211_recalc_offload(struct ieee80211_local *local)
 
 		ieee80211_recalc_sdata_offload(sdata);
 	}
-
-	mutex_unlock(&local->iflist_mtx);
 }
 
 void ieee80211_adjust_monitor_flags(struct ieee80211_sub_if_data *sdata,
@@ -1917,6 +1914,8 @@ static void ieee80211_assign_perm_addr(struct ieee80211_local *local,
 	u8 tmp_addr[ETH_ALEN];
 	int i;
 
+	lockdep_assert_wiphy(local->hw.wiphy);
+
 	/* default ... something at least */
 	memcpy(perm_addr, local->hw.wiphy->perm_addr, ETH_ALEN);
 
@@ -1924,8 +1923,6 @@ static void ieee80211_assign_perm_addr(struct ieee80211_local *local,
 	    local->hw.wiphy->n_addresses <= 1)
 		return;
 
-	mutex_lock(&local->iflist_mtx);
-
 	switch (type) {
 	case NL80211_IFTYPE_MONITOR:
 		/* doesn't matter */
@@ -1949,7 +1946,7 @@ static void ieee80211_assign_perm_addr(struct ieee80211_local *local,
 				if (!ieee80211_sdata_running(sdata))
 					continue;
 				memcpy(perm_addr, sdata->vif.addr, ETH_ALEN);
-				goto out_unlock;
+				return;
 			}
 		}
 		fallthrough;
@@ -2035,9 +2032,6 @@ static void ieee80211_assign_perm_addr(struct ieee80211_local *local,
 
 		break;
 	}
-
- out_unlock:
-	mutex_unlock(&local->iflist_mtx);
 }
 
 int ieee80211_if_add(struct ieee80211_local *local, const char *name,
@@ -2051,6 +2045,7 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
 	int ret, i;
 
 	ASSERT_RTNL();
+	lockdep_assert_wiphy(local->hw.wiphy);
 
 	if (type == NL80211_IFTYPE_P2P_DEVICE || type == NL80211_IFTYPE_NAN) {
 		struct wireless_dev *wdev;
@@ -2217,6 +2212,7 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
 void ieee80211_if_remove(struct ieee80211_sub_if_data *sdata)
 {
 	ASSERT_RTNL();
+	lockdep_assert_wiphy(sdata->local->hw.wiphy);
 
 	mutex_lock(&sdata->local->iflist_mtx);
 	list_del_rcu(&sdata->list);