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wifi: mt76: mt7921: drop TXRX_NOTIFY on non-mmio buses

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PKT_TYPE_TXRX_NOTIFY is an mmio-only event, but mt7921_rx_check() and
mt7921_queue_rx_skb() dispatch it to mt7921_mac_tx_free() on every bus.
mt7921_mac_tx_free() cleans the DMA tx queues with
mt76_queue_tx_cleanup(), which calls queue_ops->tx_cleanup(). Only the
mmio queue ops implement that callback; on USB and SDIO it is NULL, so
a TXRX_NOTIFY there calls a NULL pointer in the RX worker:

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  RIP: 0010:0x0
  Call Trace:
   mt7921_mac_tx_free+0x64/0x310 [mt7921_common]
   mt7921_rx_check+0x5f/0xf0 [mt7921_common]
   mt76u_rx_worker+0x1b9/0x620 [mt76_usb]

Drop the event on non-mmio buses via mt76_is_mmio(), as in
commit 5683e1488a ("wifi: mt76: connac: do not check WED status for
non-mmio devices").

Fixes: 48fab5bbef ("mt76: mt7921: introduce mt7921s support")
Cc: stable@vger.kernel.org
Signed-off-by: Devin Wittmayer <lucid_duck@justthetip.ca>
Link: https://patch.msgid.link/20260627191336.20223-2-lucid_duck@justthetip.ca
Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Devin Wittmayer 2026-06-27 12:13:34 -07:00 committed by Felix Fietkau
parent 29ab31f3f2
commit da4082e91a
1 changed files with 7 additions and 3 deletions
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10
drivers/net/wireless/mediatek/mt76/mt7921/mac.c
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@ -570,8 +570,9 @@ bool mt7921_rx_check(struct mt76_dev *mdev, void *data, int len)
switch (type) {
case PKT_TYPE_TXRX_NOTIFY:
/* PKT_TYPE_TXRX_NOTIFY can be received only by mmio devices */
mt7921_mac_tx_free(dev, data, len); /* mmio */
if (!mt76_is_mmio(mdev))
return false;
mt7921_mac_tx_free(dev, data, len);
return false;
case PKT_TYPE_TXS:
for (rxd += 2; rxd + 8 <= end; rxd += 8)
@ -600,7 +601,10 @@ void mt7921_queue_rx_skb(struct mt76_dev *mdev, enum mt76_rxq_id q,
switch (type) {
case PKT_TYPE_TXRX_NOTIFY:
/* PKT_TYPE_TXRX_NOTIFY can be received only by mmio devices */
if (!mt76_is_mmio(mdev)) {
napi_consume_skb(skb, 1);
break;
}
mt7921_mac_tx_free(dev, skb->data, skb->len);
napi_consume_skb(skb, 1);
break;