6.6-stable review patch. If anyone has any objections, please let me know.
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From: Louis-Alexis Eyraud louisalexis.eyraud@collabora.com
[ Upstream commit 6fe0866014486736cc3ba1c6fd4606d3dbe55c9c ]
Use spin_lock_irqsave and spin_unlock_irqrestore instead of spin_lock and spin_unlock in mtk_star_emac driver to avoid spinlock recursion occurrence that can happen when enabling the DMA interrupts again in rx/tx poll.
``` BUG: spinlock recursion on CPU#0, swapper/0/0 lock: 0xffff00000db9cf20, .magic: dead4ead, .owner: swapper/0/0, .owner_cpu: 0 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.15.0-rc2-next-20250417-00001-gf6a27738686c-dirty #28 PREEMPT Hardware name: MediaTek MT8365 Open Platform EVK (DT) Call trace: show_stack+0x18/0x24 (C) dump_stack_lvl+0x60/0x80 dump_stack+0x18/0x24 spin_dump+0x78/0x88 do_raw_spin_lock+0x11c/0x120 _raw_spin_lock+0x20/0x2c mtk_star_handle_irq+0xc0/0x22c [mtk_star_emac] __handle_irq_event_percpu+0x48/0x140 handle_irq_event+0x4c/0xb0 handle_fasteoi_irq+0xa0/0x1bc handle_irq_desc+0x34/0x58 generic_handle_domain_irq+0x1c/0x28 gic_handle_irq+0x4c/0x120 do_interrupt_handler+0x50/0x84 el1_interrupt+0x34/0x68 el1h_64_irq_handler+0x18/0x24 el1h_64_irq+0x6c/0x70 regmap_mmio_read32le+0xc/0x20 (P) _regmap_bus_reg_read+0x6c/0xac _regmap_read+0x60/0xdc regmap_read+0x4c/0x80 mtk_star_rx_poll+0x2f4/0x39c [mtk_star_emac] __napi_poll+0x38/0x188 net_rx_action+0x164/0x2c0 handle_softirqs+0x100/0x244 __do_softirq+0x14/0x20 ____do_softirq+0x10/0x20 call_on_irq_stack+0x24/0x64 do_softirq_own_stack+0x1c/0x40 __irq_exit_rcu+0xd4/0x10c irq_exit_rcu+0x10/0x1c el1_interrupt+0x38/0x68 el1h_64_irq_handler+0x18/0x24 el1h_64_irq+0x6c/0x70 cpuidle_enter_state+0xac/0x320 (P) cpuidle_enter+0x38/0x50 do_idle+0x1e4/0x260 cpu_startup_entry+0x34/0x3c rest_init+0xdc/0xe0 console_on_rootfs+0x0/0x6c __primary_switched+0x88/0x90 ```
Fixes: 0a8bd81fd6aa ("net: ethernet: mtk-star-emac: separate tx/rx handling with two NAPIs") Signed-off-by: Louis-Alexis Eyraud louisalexis.eyraud@collabora.com Reviewed-by: Maxime Chevallier maxime.chevallier@bootlin.com Acked-by: Bartosz Golaszewski bartosz.golaszewski@linaro.org Link: https://patch.msgid.link/20250424-mtk_star_emac-fix-spinlock-recursion-issue... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mediatek/mtk_star_emac.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/mediatek/mtk_star_emac.c b/drivers/net/ethernet/mediatek/mtk_star_emac.c index 25989c79c92e6..47a00e02365a2 100644 --- a/drivers/net/ethernet/mediatek/mtk_star_emac.c +++ b/drivers/net/ethernet/mediatek/mtk_star_emac.c @@ -1163,6 +1163,7 @@ static int mtk_star_tx_poll(struct napi_struct *napi, int budget) struct net_device *ndev = priv->ndev; unsigned int head = ring->head; unsigned int entry = ring->tail; + unsigned long flags;
while (entry != head && count < (MTK_STAR_RING_NUM_DESCS - 1)) { ret = mtk_star_tx_complete_one(priv); @@ -1182,9 +1183,9 @@ static int mtk_star_tx_poll(struct napi_struct *napi, int budget) netif_wake_queue(ndev);
if (napi_complete(napi)) { - spin_lock(&priv->lock); + spin_lock_irqsave(&priv->lock, flags); mtk_star_enable_dma_irq(priv, false, true); - spin_unlock(&priv->lock); + spin_unlock_irqrestore(&priv->lock, flags); }
return 0; @@ -1341,6 +1342,7 @@ static int mtk_star_rx(struct mtk_star_priv *priv, int budget) static int mtk_star_rx_poll(struct napi_struct *napi, int budget) { struct mtk_star_priv *priv; + unsigned long flags; int work_done = 0;
priv = container_of(napi, struct mtk_star_priv, rx_napi); @@ -1348,9 +1350,9 @@ static int mtk_star_rx_poll(struct napi_struct *napi, int budget) work_done = mtk_star_rx(priv, budget); if (work_done < budget) { napi_complete_done(napi, work_done); - spin_lock(&priv->lock); + spin_lock_irqsave(&priv->lock, flags); mtk_star_enable_dma_irq(priv, true, false); - spin_unlock(&priv->lock); + spin_unlock_irqrestore(&priv->lock, flags); }
return work_done;