[PATCH net-next v3] net: stmmac: unwind the WoL IRQ after a safety IRQ request failure

[James Hilliard <james.hilliard1@gmail.com>]

The safety IRQ is requested after the MAC and optional WoL IRQs. If its
request fails, stmmac_free_irq() frees the unregistered safety IRQ and
leaks the WoL handler. This can warn about an already-free IRQ and make
the next open fail.

Move the safety and WoL cleanup labels into reverse acquisition order.

This was found by code inspection while working on the stmmac MTU/resume
recovery series. Injecting a safety IRQ request failure in QEMU with
mocked MAC/DMA hardware reproduced the "Trying to free already-free IRQ"
warning and leaked WoL handler. The failure has not been observed without
fault injection.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
Changes in v3:
- Rebase onto net-next and drop the Fixes tag as requested.
- Describe how the issue was found and reproduced in the commit message.
- Add Maxime Chevallier's Reviewed-by.
- No code changes.
- Link to v2: https://patch.msgid.link/20261006-stmmac-irq-unwind-v2-1-194591c87460@gmail.com

Changes in v2:
- Drop the claim that later per-queue IRQ failures also had broken
  cleanup; those paths already released both IRQs.
- Add Nicolai Buchwitz's Reviewed-by.
- Link to v1: https://patch.msgid.link/20260930-stmmac-irq-unwind-v1-1-0c8a053761c7@gmail.com
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 56d89a696272..3ce2d5994c61 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3821,13 +3821,13 @@ static void stmmac_free_irq(struct net_device *dev,
 			free_irq(msi->sfty_ce_irq, dev);
 		fallthrough;
 	case REQ_IRQ_ERR_SFTY_CE:
-		if (priv->wol_irq > 0 && priv->wol_irq != dev->irq)
-			free_irq(priv->wol_irq, dev);
-		fallthrough;
-	case REQ_IRQ_ERR_SFTY:
 		if (priv->sfty_irq > 0 && priv->sfty_irq != dev->irq)
 			free_irq(priv->sfty_irq, dev);
 		fallthrough;
+	case REQ_IRQ_ERR_SFTY:
+		if (priv->wol_irq > 0 && priv->wol_irq != dev->irq)
+			free_irq(priv->wol_irq, dev);
+		fallthrough;
 	case REQ_IRQ_ERR_WOL:
 		free_irq(dev->irq, dev);
 		fallthrough;

---
base-commit: 05b5019b01fb9443b09ae4ed34af1135a80a84c8
change-id: 20260930-stmmac-irq-unwind-0be86901638d

Best regards,
--  
James Hilliard <james.hilliard1@gmail.com>