[PATCH] net: stmmac: remove STMMAC_DOWN check to avoid irq storm

[Xiaochuan Li]

The stmmac interrupt handlers return IRQ_HANDLED immediately when
STMMAC_DOWN is set, without reading or clearing any device status
register.

STMMAC_DOWN is set by stmmac_reset_subtask() before dev_close(). The
device interrupt is level triggered, so if it fires after STMMAC_DOWN
is set and before the IRQs are masked/freed in __stmmac_release(), the
pending status is never cleared, the line stays asserted and the handler
is re-entered forever. Since the handler returns IRQ_HANDLED,
note_interrupt() never flags the IRQ as spurious and never disables it,
resulting in an interrupt storm.

Signed-off-by: Xiaochuan Li <chuanx2070 at 163.com>
---
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 33 ++++++++-----------
 1 file changed, 13 insertions(+), 20 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 56d89a696272..520c1b8d736c 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3091,6 +3091,13 @@ static bool stmmac_safety_feat_interrupt(struct stmmac_priv *priv)
 
 	ret = stmmac_safety_feat_irq_status(priv, priv->dev,
 			priv->ioaddr, priv->dma_cap.asp, &priv->sstats);
+
+	/* Status is read/cleared; do not escalate to a global error reset
+	 * while the interface is going down.
+	 */
+	if (test_bit(STMMAC_DOWN, &priv->state))
+		return false;
+
 	if (ret && (ret != -EINVAL)) {
 		stmmac_global_err(priv);
 		return true;
@@ -3113,6 +3120,12 @@ static int stmmac_napi_check(struct stmmac_priv *priv, u32 chan, u32 dir)
 	rx_napi = rx_q->xsk_pool ? &ch->rxtx_napi : &ch->rx_napi;
 	tx_napi = tx_q->xsk_pool ? &ch->rxtx_napi : &ch->tx_napi;
 
+	/* Status was already read (and clear) above, so the irq line is
+	 * deasserted, Drop the event while the interface is going down.
+	 */
+	if (test_bit(STMMAC_DOWN, &priv->state))
+		return 0;
+
 	if ((status & handle_rx) && (chan < priv->plat->rx_queues_to_use)) {
 		if (napi_schedule_prep(rx_napi)) {
 			spin_lock_irqsave(&ch->lock, flags);
@@ -6408,10 +6421,6 @@ static irqreturn_t stmmac_interrupt(int irq, void *dev_id)
 	struct net_device *dev = (struct net_device *)dev_id;
 	struct stmmac_priv *priv = netdev_priv(dev);
 
-	/* Check if adapter is up */
-	if (test_bit(STMMAC_DOWN, &priv->state))
-		return IRQ_HANDLED;
-
 	/* Check ASP error if it isn't delivered via an individual IRQ */
 	if (priv->sfty_irq <= 0 && stmmac_safety_feat_interrupt(priv))
 		return IRQ_HANDLED;
@@ -6430,10 +6439,6 @@ static irqreturn_t stmmac_mac_interrupt(int irq, void *dev_id)
 	struct net_device *dev = (struct net_device *)dev_id;
 	struct stmmac_priv *priv = netdev_priv(dev);
 
-	/* Check if adapter is up */
-	if (test_bit(STMMAC_DOWN, &priv->state))
-		return IRQ_HANDLED;
-
 	/* To handle Common interrupts */
 	stmmac_common_interrupt(priv);
 
@@ -6445,10 +6450,6 @@ static irqreturn_t stmmac_safety_interrupt(int irq, void *dev_id)
 	struct net_device *dev = (struct net_device *)dev_id;
 	struct stmmac_priv *priv = netdev_priv(dev);
 
-	/* Check if adapter is up */
-	if (test_bit(STMMAC_DOWN, &priv->state))
-		return IRQ_HANDLED;
-
 	/* Check if a fatal error happened */
 	stmmac_safety_feat_interrupt(priv);
 
@@ -6466,10 +6467,6 @@ static irqreturn_t stmmac_msi_intr_tx(int irq, void *data)
 	dma_conf = container_of(tx_q, struct stmmac_dma_conf, tx_queue[chan]);
 	priv = container_of(dma_conf, struct stmmac_priv, dma_conf);
 
-	/* Check if adapter is up */
-	if (test_bit(STMMAC_DOWN, &priv->state))
-		return IRQ_HANDLED;
-
 	status = stmmac_napi_check(priv, chan, DMA_DIR_TX);
 
 	if (unlikely(status & tx_hard_error_bump_tc)) {
@@ -6492,10 +6489,6 @@ static irqreturn_t stmmac_msi_intr_rx(int irq, void *data)
 	dma_conf = container_of(rx_q, struct stmmac_dma_conf, rx_queue[chan]);
 	priv = container_of(dma_conf, struct stmmac_priv, dma_conf);
 
-	/* Check if adapter is up */
-	if (test_bit(STMMAC_DOWN, &priv->state))
-		return IRQ_HANDLED;
-
 	stmmac_napi_check(priv, chan, DMA_DIR_RX);
 
 	return IRQ_HANDLED;
-- 
2.43.0