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 <miquel.raynal@bootlin.com>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20220519150516.443078-6-miquel.raynal@bootlin.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/net/mac802154/ieee802154_i.h b/net/mac802154/ieee802154_i.h
index a8b7b9049f14..0c7ff9e0b632 100644
--- a/net/mac802154/ieee802154_i.h
+++ b/net/mac802154/ieee802154_i.h
@@ -130,6 +130,25 @@ netdev_tx_t
 ieee802154_subif_start_xmit(struct sk_buff *skb, struct net_device *dev);
 enum hrtimer_restart ieee802154_xmit_ifs_timer(struct hrtimer *timer);
 
+/**
+ * ieee802154_hold_queue - hold ieee802154 queue
+ * @local: main mac object
+ *
+ * Hold a queue by incrementing an atomic counter and requesting the netif
+ * queues to be stopped. The queues cannot be woken up while the counter has not
+ * been reset with as any ieee802154_release_queue() calls as needed.
+ */
+void ieee802154_hold_queue(struct ieee802154_local *local);
+
+/**
+ * ieee802154_release_queue - release ieee802154 queue
+ * @local: main mac object
+ *
+ * Release a queue which is held by decrementing an atomic counter and wake it
+ * up only if the counter reaches 0.
+ */
+void ieee802154_release_queue(struct ieee802154_local *local);
+
 /* MIB callbacks */
 void mac802154_dev_set_page_channel(struct net_device *dev, u8 page, u8 chan);