[PATCH net-next v3 02/12] net: ethernet: cortina: Keep shared free queue parent-owned

[Linus Walleij <linusw@kernel.org>]

The software free queue is shared by both Ethernet ports, but each
child removal tears it down. The parent removal then tears it down once
more. This can destroy the queue while the sibling port is active and can
free it repeatedly.

Depopulate both port devices before cleaning up the queue, and perform
that cleanup only from the parent. Disable the free-queue interrupt after
the managed handlers have drained, since its threaded handler can
re-enable it. Guard cleanup for probe and removal paths where no queue was
allocated.

Reported-by: Myeonghun Pak <mhun512@gmail.com>
Closes: https://lore.kernel.org/netdev/20260917192835.58126-1-mhun512@gmail.com/
Fixes: 4d5ae32f5e1e ("net: ethernet: Add a driver for Gemini gigabit ethernet")
Assisted-by: LLM
Signed-off-by: Linus Walleij <linusw@kernel.org>
---
 drivers/net/ethernet/cortina/gemini.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cortina/gemini.c b/drivers/net/ethernet/cortina/gemini.c
index 2be3e9051981..15ad9f721dd5 100644
--- a/drivers/net/ethernet/cortina/gemini.c
+++ b/drivers/net/ethernet/cortina/gemini.c
@@ -1004,6 +1004,9 @@ static void geth_cleanup_freeq(struct gemini_ethernet *geth)
 	unsigned int pages = len >> fpp_order;
 	unsigned int pn;
 
+	if (!geth->freeq_ring)
+		return;
+
 	writew(readw(geth->base + GLOBAL_SWFQ_RWPTR_REG),
 	       geth->base + GLOBAL_SWFQ_RWPTR_REG + 2);
 	writel(0, geth->base + GLOBAL_SW_FREEQ_BASE_SIZE_REG);
@@ -2405,7 +2408,6 @@ static void gemini_port_remove(struct gemini_ethernet_port *port)
 		unregister_netdev(port->netdev);
 	}
 	clk_disable_unprepare(port->pclk);
-	geth_cleanup_freeq(port->geth);
 	gemini_port_clear(port);
 }
 
@@ -2706,6 +2708,8 @@ static void gemini_ethernet_remove(struct platform_device *pdev)
 {
 	struct gemini_ethernet *geth = platform_get_drvdata(pdev);
 
+	devm_of_platform_depopulate(&pdev->dev);
+	writel(0, geth->base + GLOBAL_INTERRUPT_ENABLE_4_REG);
 	geth_cleanup_freeq(geth);
 	geth->initialized = false;
 }

-- 
2.55.0