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 documenation 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 --- net/batman-adv/translation-table.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index 85293283..2d52356a 100644 --- 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;