From 36c2009d90f2210ef92e6f4f2850e8b57b09e754 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Gajdos=20Tam=C3=A1s?= Date: Mon, 21 Sep 2026 11:13:32 +0200 Subject: [PATCH 1/3] net: atl1c: fix soft lockup on out-of-range tpd_cons read MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The hardware can report an out-of-range tpd_cons (seen as 0xffff) while the PCIe link/MAC is resetting. An out-of-range value can never be reached and the loop below would spin forever. To avoid a soft lockup treat it as "nothing new to clean" instead. Reproduced on two machines, same NIC (Qualcomm Atheros AR8151 v2.0, 4-port), triggered by rebooting a Mikrotik CCR2004 PCIe card that the ports are directly linked to: - Ubuntu 26.04.1 LTS, kernel 7.0.0-31-generic. The link-flap precursor, before the lockup was captured with a full trace elsewhere: atl1c 0000:05:00.0 enp5s0f0: NETDEV WATCHDOG: CPU: 4: transmit queue 2 timed out 489984 ms atl1c 0000:05:00.0: MAC state machine can't be idle since disabled for 10ms second atl1c 0000:05:00.0: atl1c: enp5s0f0 NIC Link is Up<65535 Mbps Full Duplex> 65535 (0xffff) here is the same value tpd_cons reads back once the loop below gets stuck. - Proxmox VE, kernel 7.0.14-11-pve. Same NIC/trigger, this time caught by the soft lockup watchdog with a full stack trace: watchdog: BUG: soft lockup - CPU#12 stuck for 354s! [napi/eth%d-0:329] CPU: 12 UID: 0 PID: 329 Comm: napi/eth%d-0 Tainted: P O L 7.0.14-11-pve #1 PREEMPT(lazy) RIP: 0010:atl1c_clean_tx+0x142/0x2d0 [atl1c] Call Trace: __napi_poll+0x32/0x1e0 napi_threaded_poll_loop+0x286/0x2e0 napi_threaded_poll+0xfd/0x140 kthread+0xf7/0x130 ret_from_fork+0x2da/0x3a0 ret_from_fork_asm+0x1a/0x30 Fixes: 43250ddd75a35d ("atl1c: Atheros L1C Gigabit Ethernet driver") Cc: stable@vger.kernel.org Signed-off-by: Gajdos Tamás Link: https://patch.msgid.link/20260921091334.3571525-2-tamas@rimpianto.com Signed-off-by: Paolo Abeni --- drivers/net/ethernet/atheros/atl1c/atl1c_main.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c index 7efa3fc257b3..e58f1d2c26bd 100644 --- a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c +++ b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c @@ -1602,6 +1602,9 @@ static int atl1c_clean_tx(struct napi_struct *napi, int budget) AT_READ_REGW(&adapter->hw, atl1c_qregs[tpd_ring->num].tpd_cons, &hw_next_to_clean); + if (unlikely(hw_next_to_clean >= tpd_ring->count)) + hw_next_to_clean = next_to_clean; + while (next_to_clean != hw_next_to_clean) { buffer_info = &tpd_ring->buffer_info[next_to_clean]; if (buffer_info->skb) { From 374bf9e4b90f979e052332c4faca2d745c491a12 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Gajdos=20Tam=C3=A1s?= Date: Mon, 21 Sep 2026 11:13:33 +0200 Subject: [PATCH 2/3] net: atl1e: fix soft lockup on out-of-range hw_next_to_clean read MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Same issue as atl1c (see the first commit in this series, "net: atl1c: fix soft lockup on out-of-range tpd_cons read"): the hardware can report an out-of-range hw_next_to_clean (seen as 0xffff) while the PCIe link/MAC is resetting. An out-of-range value can never be reached and the loop below would spin forever. Treat it as "nothing new to clean" instead. Fixes: a6a5325239c202 ("atl1e: Atheros L1E Gigabit Ethernet driver") Cc: stable@vger.kernel.org Signed-off-by: Gajdos Tamás Link: https://patch.msgid.link/20260921091334.3571525-3-tamas@rimpianto.com Signed-off-by: Paolo Abeni --- drivers/net/ethernet/atheros/atl1e/atl1e_main.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/net/ethernet/atheros/atl1e/atl1e_main.c b/drivers/net/ethernet/atheros/atl1e/atl1e_main.c index 40290028580b..437989edb780 100644 --- a/drivers/net/ethernet/atheros/atl1e/atl1e_main.c +++ b/drivers/net/ethernet/atheros/atl1e/atl1e_main.c @@ -1234,6 +1234,9 @@ static bool atl1e_clean_tx_irq(struct atl1e_adapter *adapter) u16 hw_next_to_clean = AT_READ_REGW(&adapter->hw, REG_TPD_CONS_IDX); u16 next_to_clean = atomic_read(&tx_ring->next_to_clean); + if (unlikely(hw_next_to_clean >= tx_ring->count)) + hw_next_to_clean = next_to_clean; + while (next_to_clean != hw_next_to_clean) { tx_buffer = &tx_ring->tx_buffer[next_to_clean]; if (tx_buffer->dma) { From 43e746821f5f5afbbf68e388bf9fbe221e03bfca Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Gajdos=20Tam=C3=A1s?= Date: Mon, 21 Sep 2026 11:13:34 +0200 Subject: [PATCH 3/3] net: atl1: fix soft lockup on out-of-range cmb_tpd_next_to_clean read MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Same issue as atl1c (see the first commit in this series, "net: atl1c: fix soft lockup on out-of-range tpd_cons read"): the hardware can report an out-of-range cmb_tpd_next_to_clean (seen as 0xffff) while the PCIe link/MAC is resetting. An out-of-range value can never be reached and the loop below would spin forever. Treat it as "nothing new to clean" instead. Fixes: f3cc28c797604f ("Add Attansic L1 ethernet driver.") Cc: stable@vger.kernel.org Signed-off-by: Gajdos Tamás Link: https://patch.msgid.link/20260921091334.3571525-4-tamas@rimpianto.com Signed-off-by: Paolo Abeni --- drivers/net/ethernet/atheros/atlx/atl1.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/net/ethernet/atheros/atlx/atl1.c b/drivers/net/ethernet/atheros/atlx/atl1.c index 98a4d089270e..957d5598dda5 100644 --- a/drivers/net/ethernet/atheros/atlx/atl1.c +++ b/drivers/net/ethernet/atheros/atlx/atl1.c @@ -2066,6 +2066,9 @@ static int atl1_intr_tx(struct atl1_adapter *adapter) sw_tpd_next_to_clean = atomic_read(&tpd_ring->next_to_clean); cmb_tpd_next_to_clean = le16_to_cpu(adapter->cmb.cmb->tpd_cons_idx); + if (unlikely(cmb_tpd_next_to_clean >= tpd_ring->count)) + cmb_tpd_next_to_clean = sw_tpd_next_to_clean; + while (cmb_tpd_next_to_clean != sw_tpd_next_to_clean) { buffer_info = &tpd_ring->buffer_info[sw_tpd_next_to_clean]; if (buffer_info->dma) {