net: mac802154: Introduce a tx queue flushing mechanism

Right now we are able to stop a queue but we have no indication if a
transmission is ongoing or not.

Thanks to recent additions, we can track the number of ongoing
transmissions so we know if the last transmission is over. Adding on top
of it an internal wait queue also allows to be woken up asynchronously
when this happens. If, beforehands, we marked the queue to be held and
stopped it, we end up flushing and stopping the tx queue.

Thanks to this feature, we will soon be able to introduce a synchronous
transmit API.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20220519150516.443078-9-miquel.raynal@bootlin.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h
index e87f1b07f20f672fdf5539833f575ef47ded8ce3..0804d79669a433c6aefab8dd89eeaef5ec9690eb 100644 (file)
--- a/include/net/cfg802154.h
+++ b/include/net/cfg802154.h
@@ -218,6 +218,7 @@ struct wpan_phy {
        spinlock_t queue_lock;
        atomic_t ongoing_txs;
        atomic_t hold_txs;
+       wait_queue_head_t sync_txq;
 
        char priv[] __aligned(NETDEV_ALIGN);
 };

diff --git a/net/ieee802154/core.c b/net/ieee802154/core.c
index 47a4de6df88bc594b837ac053095469a3d7c9345..57546e07e06ade19af02acdd43f18e9b05b40797 100644 (file)
--- a/net/ieee802154/core.c
+++ b/net/ieee802154/core.c
@@ -129,6 +129,7 @@ wpan_phy_new(const struct cfg802154_ops *ops, size_t priv_size)
        wpan_phy_net_set(&rdev->wpan_phy, &init_net);
 
        init_waitqueue_head(&rdev->dev_wait);
+       init_waitqueue_head(&rdev->wpan_phy.sync_txq);
 
        spin_lock_init(&rdev->wpan_phy.queue_lock);
 

diff --git a/net/mac802154/cfg.c b/net/mac802154/cfg.c
index b51100fd9e3f2a2317d505b77ed8d248a0e0476a..93df24f7557247e80051ed4719684b5e23e6f52c 100644 (file)
--- a/net/mac802154/cfg.c
+++ b/net/mac802154/cfg.c
@@ -46,7 +46,7 @@ static int ieee802154_suspend(struct wpan_phy *wpan_phy)
        if (!local->open_count)
                goto suspend;
 
-       ieee802154_hold_queue(local);
+       ieee802154_sync_and_hold_queue(local);
        synchronize_net();
 
        /* stop hardware - this must stop RX */

diff --git a/net/mac802154/ieee802154_i.h b/net/mac802154/ieee802154_i.h
index e34db1d49ef4343bb014ff83947876caf9f0e6d5..a057827fc48a5c66bbc9ba3a7b82605143445e83 100644 (file)
--- a/net/mac802154/ieee802154_i.h
+++ b/net/mac802154/ieee802154_i.h
@@ -124,6 +124,7 @@ extern struct ieee802154_mlme_ops mac802154_mlme_wpan;
 
 void ieee802154_rx(struct ieee802154_local *local, struct sk_buff *skb);
 void ieee802154_xmit_sync_worker(struct work_struct *work);
+int ieee802154_sync_and_hold_queue(struct ieee802154_local *local);
 netdev_tx_t
 ieee802154_monitor_start_xmit(struct sk_buff *skb, struct net_device *dev);
 netdev_tx_t

diff --git a/net/mac802154/tx.c b/net/mac802154/tx.c
index 607019b8f8ab5cfee4b4040bbd5ae7327c38d62e..38f74b8b674029bf933fe5ea9d4acb7a1e29536c 100644 (file)
--- a/net/mac802154/tx.c
+++ b/net/mac802154/tx.c
@@ -44,7 +44,8 @@ void ieee802154_xmit_sync_worker(struct work_struct *work)
 err_tx:
        /* Restart the netif queue on each sub_if_data object. */
        ieee802154_release_queue(local);
-       atomic_dec(&local->phy->ongoing_txs);
+       if (!atomic_dec_and_test(&local->phy->ongoing_txs))
+               wake_up(&local->phy->sync_txq);
        kfree_skb(skb);
        netdev_dbg(dev, "transmission failed\n");
 }
@@ -100,12 +101,33 @@ ieee802154_tx(struct ieee802154_local *local, struct sk_buff *skb)
 
 err_wake_netif_queue:
        ieee802154_release_queue(local);
-       atomic_dec(&local->phy->ongoing_txs);
+       if (!atomic_dec_and_test(&local->phy->ongoing_txs))
+               wake_up(&local->phy->sync_txq);
 err_free_skb:
        kfree_skb(skb);
        return NETDEV_TX_OK;
 }
 
+static int ieee802154_sync_queue(struct ieee802154_local *local)
+{
+       int ret;
+
+       ieee802154_hold_queue(local);
+       ieee802154_disable_queue(local);
+       wait_event(local->phy->sync_txq, !atomic_read(&local->phy->ongoing_txs));
+       ret = local->tx_result;
+       ieee802154_release_queue(local);
+
+       return ret;
+}
+
+int ieee802154_sync_and_hold_queue(struct ieee802154_local *local)
+{
+       ieee802154_hold_queue(local);
+
+       return ieee802154_sync_queue(local);
+}
+
 static netdev_tx_t
 ieee802154_hot_tx(struct ieee802154_local *local, struct sk_buff *skb)
 {

diff --git a/net/mac802154/util.c b/net/mac802154/util.c
index 999534f644854b229ecd2ac2d5b8208c597239b2..5e1fcc7b0123bd1e751a7f67dead26c5137f517a 100644 (file)
--- a/net/mac802154/util.c
+++ b/net/mac802154/util.c
@@ -140,7 +140,8 @@ void ieee802154_xmit_complete(struct ieee802154_hw *hw, struct sk_buff *skb,
        }
 
        dev_consume_skb_any(skb);
-       atomic_dec(&hw->phy->ongoing_txs);
+       if (!atomic_dec_and_test(&hw->phy->ongoing_txs))
+               wake_up(&hw->phy->sync_txq);
 }
 EXPORT_SYMBOL(ieee802154_xmit_complete);
 
@@ -152,7 +153,8 @@ void ieee802154_xmit_error(struct ieee802154_hw *hw, struct sk_buff *skb,
        local->tx_result = reason;
        ieee802154_release_queue(local);
        dev_kfree_skb_any(skb);
-       atomic_dec(&hw->phy->ongoing_txs);
+       if (!atomic_dec_and_test(&hw->phy->ongoing_txs))
+               wake_up(&hw->phy->sync_txq);
 }
 EXPORT_SYMBOL(ieee802154_xmit_error);