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mac802154: Send beacons using the MLME Tx path

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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: 3accf47627 ("mac802154: Handle basic beaconing")
Reported-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20230214135035.1202471-5-miquel.raynal@bootlin.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
This commit is contained in:
Miquel Raynal 2023-02-14 14:50:33 +01:00 committed by Stefan Schmidt
parent 1edecbd0bd
commit 1375e3ba9d
1 changed files with 19 additions and 1 deletions
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20
net/mac802154/scan.c
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@ -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)