[PATCH v2 1/9] gpio: mxc: fix race between chained IRQ handler install and probe completion

[Peng Fan (OSS)]

From: Peng Fan <peng.fan@xxxxxxx>

mxc_update_irq_chained_handler() is called before the IRQ domain, the
generic IRQ chip, and the port list entry are set up. If an interrupt
arrives in that window:

 - mx3_gpio_irq_handler() calls generic_handle_domain_irq() with
   port->domain still NULL.
 - mx2_gpio_irq_handler() walks mxc_gpio_ports, but the port has not
   been added to the list yet.

Additionally, if any of the subsequent probe steps
(gpio_generic_chip_init(), devm_gpiochip_add_data(),
irq_domain_create_legacy(), or mxc_gpio_init_gc()) fail, the error
paths never unregister the chained handler, leaving a dangling handler
that points at freed memory.

Move the handler installation after all its dependencies are ready and
after list_add_tail(), so the handler is never live while the data
structures it touches are incomplete, and is never installed if probe
fails.

Fixes: 5f6d1998adeb ("gpio: mxc: release the parent IRQ in runtime suspend")
Assisted-by: LLM
Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
---
 drivers/gpio/gpio-mxc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-mxc.c b/drivers/gpio/gpio-mxc.c
index 7e2690d92df6..e05f276a50e8 100644
--- a/drivers/gpio/gpio-mxc.c
+++ b/drivers/gpio/gpio-mxc.c
@@ -474,8 +474,6 @@ static int mxc_gpio_probe(struct platform_device *pdev)
 	} else
 		port->mx_irq_handler = mx3_gpio_irq_handler;
 
-	mxc_update_irq_chained_handler(port, true);
-
 	config.dev = &pdev->dev;
 	config.sz = 4;
 	config.dat = port->base + GPIO_PSR;
@@ -525,6 +523,8 @@ static int mxc_gpio_probe(struct platform_device *pdev)
 
 	list_add_tail(&port->node, &mxc_gpio_ports);
 
+	mxc_update_irq_chained_handler(port, true);
+
 	platform_set_drvdata(pdev, port);
 	pm_runtime_put_autosuspend(&pdev->dev);
 

-- 
2.51.0