net: mac802154: Add a warning in the slow path

In order to be able to detect possible conflicts between the net
interface core and the ieee802154 core, let's add a warning in the slow
path: we want to be sure that whenever we start an asynchronous MLME
transmission (which can be fully asynchronous) the net core somehow
agrees that this transmission is possible, ie. the device was not
stopped. Warning in this case would allow us to track down more easily
possible issues with the MLME logic if we ever get reports.

Unlike in the hot path, such a situation cannot be handled.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20220519150516.443078-12-miquel.raynal@bootlin.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

diff --git a/net/mac802154/tx.c b/net/mac802154/tx.c
index 6188f42276e781f7d837d0ce739f227ba7320798..5b471e9322713c02c0b2c2f621fbe2e88a323a07 100644 (file)
--- a/net/mac802154/tx.c
+++ b/net/mac802154/tx.c
@@ -132,6 +132,25 @@ int ieee802154_sync_and_hold_queue(struct ieee802154_local *local)
        return ret;
 }
 
+static bool ieee802154_netif_is_down(struct ieee802154_local *local)
+{
+       struct ieee802154_sub_if_data *sdata;
+       bool is_down = true;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(sdata, &local->interfaces, list) {
+               if (!sdata->dev)
+                       continue;
+
+               is_down = !netif_running(sdata->dev);
+               if (is_down)
+                       break;
+       }
+       rcu_read_unlock();
+
+       return is_down;
+}
+
 int ieee802154_mlme_op_pre(struct ieee802154_local *local)
 {
        return ieee802154_sync_and_hold_queue(local);
@@ -152,6 +171,14 @@ int ieee802154_mlme_tx(struct ieee802154_local *local, struct sk_buff *skb)
                return -ENETDOWN;
        }
 
+       /* Warn if the ieee802154 core thinks MLME frames can be sent while the
+        * net interface expects this cannot happen.
+        */
+       if (WARN_ON_ONCE(ieee802154_netif_is_down(local))) {
+               rtnl_unlock();
+               return -ENETDOWN;
+       }
+
        ieee802154_tx(local, skb);
        ret = ieee802154_sync_queue(local);