[PATCH net] net: macb: init workqueues before register_netdev()

[Théo Lebrun]

register_netdev() exposes the interface to userspace which might trigger
operations like close on it. Those access the HRESP/LPI tasks and
might therefore use them uninitialised.

Fix this race by initialising both `struct work_struct` before
register_netdev().

Theoretical bugfix. The main reason for fix is to avoid future Sashiko
reports which triggers if we grow the race condition (by touching those
workqueues at open for example). The likeliness of this bug sounds
tiny, but I've not spent any time trying to reproduce it.

Fixes: c5092ba3155e ("net: macb: Convert tasklet API to new bottom half workqueue mechanism")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: sashiko <sashiko@xxxxxxxxxxx>
Link: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260918-macb-close-v1-0-05e32ce98813%40bootlin.com
Link: https://lore.kernel.org/netdev/179010942347.2160803.5970158668197373074@xxxxxxxxxx/
Signed-off-by: Théo Lebrun <theo.lebrun@xxxxxxxxxxx>
---
 drivers/net/ethernet/cadence/macb_main.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 8e5c034dc3a4..76260b97a07b 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -5968,15 +5968,15 @@ static int macb_probe(struct platform_device *pdev)
 	if (err)
 		goto err_out_unregister_mdio;
 
+	INIT_WORK(&bp->hresp_err_bh_work, macb_hresp_error_task);
+	INIT_DELAYED_WORK(&bp->tx_lpi_work, macb_tx_lpi_work_fn);
+
 	err = register_netdev(netdev);
 	if (err) {
 		dev_err(&pdev->dev, "Cannot register net device, aborting.\n");
 		goto err_out_free_tieoff;
 	}
 
-	INIT_WORK(&bp->hresp_err_bh_work, macb_hresp_error_task);
-	INIT_DELAYED_WORK(&bp->tx_lpi_work, macb_tx_lpi_work_fn);
-
 	netdev_info(netdev, "Cadence %s rev 0x%08x at 0x%08lx irq %d (%pM)\n",
 		    macb_is_gem(bp) ? "GEM" : "MACB", macb_readl(bp, MID),
 		    netdev->base_addr, netdev->irq, netdev->dev_addr);

---
base-commit: c15c41239b491c7fa380e7ffd115ba037f2d4b11
change-id: 20260925-macb-netdev-register-race-2b4125dd5645

Best regards,
--  
Théo Lebrun <theo.lebrun@xxxxxxxxxxx>