net: ethernet: mtk-star-emac: fix spinlock recursion issues on rx/tx poll

laeyraud · gregkh · commit bedd287fdd31 · 2025-05-09T09:39:38.000+02:00
[ Upstream commit 6fe0866 ] 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 torvalds#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: 0a8bd81 ("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-v2-1-f3fde2e529d8@collabora.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Stable-dep-of: e54b4db ("net: ethernet: mtk-star-emac: rearm interrupts in rx_poll only when advised") Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/drivers/net/ethernet/mediatek/mtk_star_emac.c b/drivers/net/ethernet/mediatek/mtk_star_emac.c
@@ -1153,6 +1153,7 @@ 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);
@@ -1172,9 +1173,9 @@ 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;
@@ -1331,16 +1332,17 @@ 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);
 
 	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;
