The MACB driver has since forever leaked the outgoing SKBs that have not yet been marked as completed. They live in queue->tx_skb which gets freed without remorse nor checking. macb_free_consistent() gets called in a few codepaths, but only close will trigger the added expressions. In macb_open() and macb_alloc_consistent() failure cases, queues' tx_skb just got allocated and are empty. Fixes: 89e5785fc8a6 ("[PATCH] Atmel MACB ethernet driver") Cc: stable@vger.kernel.org Reviewed-by: Nicolai Buchwitz Signed-off-by: Théo Lebrun --- Changes in v4: - Drop the skb_drop_reason code. No other Ethernet driver does that and the reasoning (because our stats are broken) is a bad one. - Take Rb trailer from Nicolai. - Drop email that gets rejected. - Rebase upon latest net/main (d8e8b85a85fe). - Link to v3: https://patch.msgid.link/20260617-macb-drop-tx-v3-0-d4c7e57d890b@bootlin.com Changes in v3: - Drop stats fixing. A proper fix deserves its own net-next refactoring series to migrate to netdev_stat_ops (ynltool uAPI), which will come in later. We keep the tx_dropped++ because they are safe as every other context is disabled when macb_free_consistent() is called. - Rebased to latest net/main (406e8a651a7b), nothing to report. - Link to v2: https://patch.msgid.link/20260428-macb-drop-tx-v2-0-647f5199d8df@bootlin.com Changes in v2: - Increment tx_dropped stat once per SKB, not once per frame. - Reset tx_head & tx_tail to avoid keeping stalled cursors. - Fix SKB dropped reasons throughout by adding the reason as parameter to macb_tx_unmap(). This is a new patch. Then the drop-all-on-close fix can use this ability to report we are not consuming SKBs. - Add increment to stats->tx_dropped on DMA mapping failure and tx_error_task. Done as separate patches (3 and 4). - Rebase upon net/main @ 46f74a3f7d57, nothing to report. - Link to v1: https://patch.msgid.link/20260424-macb-drop-tx-v1-1-b3ecb787d84d@bootlin.com --- drivers/net/ethernet/cadence/macb_main.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index fd282a1700fb..d394f1f43b68 100644 --- a/drivers/net/ethernet/cadence/macb_main.c +++ b/drivers/net/ethernet/cadence/macb_main.c @@ -2668,8 +2668,25 @@ static void macb_free_consistent(struct macb *bp) dma_free_coherent(dev, size, bp->queues[0].rx_ring, bp->queues[0].rx_ring_dma); for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) { - kfree(queue->tx_skb); - queue->tx_skb = NULL; + if (queue->tx_skb) { + unsigned int dropped = 0, tail; + + for (tail = queue->tx_tail; tail != queue->tx_head; + tail++) { + if (macb_tx_skb(queue, tail)->skb) + dropped++; + macb_tx_unmap(bp, macb_tx_skb(queue, tail), 0); + } + + queue->stats.tx_dropped += dropped; + bp->dev->stats.tx_dropped += dropped; + + kfree(queue->tx_skb); + queue->tx_skb = NULL; + } + + queue->tx_head = 0; + queue->tx_tail = 0; queue->tx_ring = NULL; queue->rx_ring = NULL; } --- base-commit: d8e8b85a85fe21954d303db68034aac4639df88d change-id: 20260423-macb-drop-tx-f9ce72720d05 Best regards, -- Théo Lebrun