batman-adv: Avoid RCU list-traversal in spinlock

The new CONFIG_PROVE_RCU_LIST requires a condition statement in
(h)list_for_each_entry_rcu when the code might be executed in a non RCU
non-reader section with the writer lock. Otherwise lockdep might cause a
false positive warning like

  =============================
  WARNING: suspicious RCU usage
  -----------------------------
  translation-table.c:940 RCU-list traversed in non-reader section!!

batman-adv is (mostly) following the examples from the RCU documentation
and is using the normal list-traversal primitives instead of the RCU
list-traversal primitives when the writer (spin)lock is held.

The remaining users of RCU list-traversal primitives with writer spinlock
have to be converted to the same style as the rest of the code.

Reported-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 8529328..a9635c8 100644 (file)
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -862,7 +862,7 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node,
        u8 *tt_change_ptr;
 
        spin_lock_bh(&orig_node->vlan_list_lock);
-       hlist_for_each_entry_rcu(vlan, &orig_node->vlan_list, list) {
+       hlist_for_each_entry(vlan, &orig_node->vlan_list, list) {
                num_vlan++;
                num_entries += atomic_read(&vlan->tt.num_entries);
        }
@@ -888,7 +888,7 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node,
        (*tt_data)->num_vlan = htons(num_vlan);
 
        tt_vlan = (struct batadv_tvlv_tt_vlan_data *)(*tt_data + 1);
-       hlist_for_each_entry_rcu(vlan, &orig_node->vlan_list, list) {
+       hlist_for_each_entry(vlan, &orig_node->vlan_list, list) {
                tt_vlan->vid = htons(vlan->vid);
                tt_vlan->crc = htonl(vlan->tt.crc);
 
@@ -937,7 +937,7 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv,
        int change_offset;
 
        spin_lock_bh(&bat_priv->softif_vlan_list_lock);
-       hlist_for_each_entry_rcu(vlan, &bat_priv->softif_vlan_list, list) {
+       hlist_for_each_entry(vlan, &bat_priv->softif_vlan_list, list) {
                vlan_entries = atomic_read(&vlan->tt.num_entries);
                if (vlan_entries < 1)
                        continue;
@@ -967,7 +967,7 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv,
        (*tt_data)->num_vlan = htons(num_vlan);
 
        tt_vlan = (struct batadv_tvlv_tt_vlan_data *)(*tt_data + 1);
-       hlist_for_each_entry_rcu(vlan, &bat_priv->softif_vlan_list, list) {
+       hlist_for_each_entry(vlan, &bat_priv->softif_vlan_list, list) {
                vlan_entries = atomic_read(&vlan->tt.num_entries);
                if (vlan_entries < 1)
                        continue;