net: mac802154: Bring the ability to hold the transmit queue

Create a hold_txs atomic variable and increment/decrement it when
relevant, ie. when we want to hold the queue or release it: currently
all the "stopped" situations are suitable, but very soon we will more
extensively use this feature for MLME purposes.

Upon release, the atomic counter is decremented and checked. If it is
back to 0, then the netif queue gets woken up. This makes the whole
process fully transparent, provided that all the users of
ieee802154_wake/stop_queue() now call ieee802154_hold/release_queue()
instead.

In no situation individual drivers should call any of these helpers
manually in order to avoid messing with the counters. There are other
functions more suited for this purpose which have been introduced, such
as the _xmit_complete() and _xmit_error() helpers which will handle all
that for them.

One advantage is that, as no more drivers call the stop/wake helpers
directly, we can safely stop exporting them and only declare the
hold/release ones in a header only accessible to the core.

Signed-off-by: Miquel Raynal <[email protected]>
Acked-by: Alexander Aring <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Stefan Schmidt <[email protected]>

2 files changed, 4 insertions, 29 deletions

diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h
index 678ff00c7d70..e87f1b07f20f 100644
--- a/include/net/cfg802154.h
+++ b/include/net/cfg802154.h
@@ -11,7 +11,7 @@
 
 #include <linux/ieee802154.h>
 #include <linux/netdevice.h>
-#include <linux/mutex.h>
+#include <linux/spinlock.h>
 #include <linux/bug.h>
 
 #include <net/nl802154.h>
@@ -214,8 +214,10 @@ struct wpan_phy {
 	/* the network namespace this phy lives in currently */
 	possible_net_t _net;
 
-	/* Transmission monitoring */
+	/* Transmission monitoring and control */
+	spinlock_t queue_lock;
 	atomic_t ongoing_txs;
+	atomic_t hold_txs;
 
 	char priv[] __aligned(NETDEV_ALIGN);
 };
diff --git a/include/net/mac802154.h b/include/net/mac802154.h
index bdac0ddbdcdb..357d25ef627a 100644
--- a/include/net/mac802154.h
+++ b/include/net/mac802154.h
@@ -460,33 +460,6 @@ void ieee802154_unregister_hw(struct ieee802154_hw *hw);
  */
 void ieee802154_rx_irqsafe(struct ieee802154_hw *hw, struct sk_buff *skb,
 			   u8 lqi);
-/**
- * ieee802154_wake_queue - wake ieee802154 queue
- * @hw: pointer as obtained from ieee802154_alloc_hw().
- *
- * Tranceivers usually have either one transmit framebuffer or one framebuffer
- * for both transmitting and receiving. Hence, the core currently only handles
- * one frame at a time for each phy, which means we had to stop the queue to
- * avoid new skb to come during the transmission. The queue then needs to be
- * woken up after the operation.
- *
- * Drivers should use this function instead of netif_wake_queue.
- */
-void ieee802154_wake_queue(struct ieee802154_hw *hw);
-
-/**
- * ieee802154_stop_queue - stop ieee802154 queue
- * @hw: pointer as obtained from ieee802154_alloc_hw().
- *
- * Tranceivers usually have either one transmit framebuffer or one framebuffer
- * for both transmitting and receiving. Hence, the core currently only handles
- * one frame at a time for each phy, which means we need to tell upper layers to
- * stop giving us new skbs while we are busy with the transmitted one. The queue
- * must then be stopped before transmitting.
- *
- * Drivers should use this function instead of netif_stop_queue.
- */
-void ieee802154_stop_queue(struct ieee802154_hw *hw);
 
 /**
  * ieee802154_xmit_complete - frame transmission complete