Commit 1375e3ba authored by Miquel Raynal's avatar Miquel Raynal Committed by Stefan Schmidt
Browse files

mac802154: Send beacons using the MLME Tx path 



Using ieee802154_subif_start_xmit() to bypass the net queue when
sending beacons is broken because it does not acquire the
HARD_TX_LOCK(), hence not preventing datagram buffers to be smashed by
beacons upon contention situation. Using the mlme_tx helper is not the
best fit either but at least it is not buggy and has little-to-no
performance hit. More details are given in the comment explaining this
choice in the code.

Fixes: 3accf476 ("mac802154: Handle basic beaconing")
Reported-by: default avatarAlexander Aring <aahringo@redhat.com>
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20230214135035.1202471-5-miquel.raynal@bootlin.com


Signed-off-by: default avatarStefan Schmidt <stefan@datenfreihafen.org>
parent 1edecbd0

net/mac802154/scan.c

+19 −1
Original line number Diff line number Diff line
@@ -326,7 +326,25 @@ static int mac802154_transmit_beacon(struct ieee802154_local *local, 
		return ret;

	}



	return ieee802154_subif_start_xmit(skb, sdata->dev);

	/* Using the MLME transmission helper for sending beacons is a bit

	 * overkill because we do not really care about the final outcome.

	 *

	 * Even though, going through the whole net stack with a regular

	 * dev_queue_xmit() is not relevant either because we want beacons to be

	 * sent "now" rather than go through the whole net stack scheduling

	 * (qdisc & co).

	 *

	 * Finally, using ieee802154_subif_start_xmit() would only be an option

	 * if we had a generic transmit helper which would acquire the

	 * HARD_TX_LOCK() to prevent buffer handling conflicts with regular

	 * packets.

	 *

	 * So for now we keep it simple and send beacons with our MLME helper,

	 * even if it stops the ieee802154 queue entirely during these

	 * transmissions, wich anyway does not have a huge impact on the

	 * performances given the current design of the stack.

	 */

	return ieee802154_mlme_tx(local, sdata, skb);

}



void mac802154_beacon_worker(struct work_struct *work)