pps: clients: gpio: fix interrupt handling order in remove path

The interrupt handler in pps_gpio_probe() is registered after calling
pps_register_source() using devm_request_irq(). However, in the
corresponding remove function, pps_unregister_source() is called before
the IRQ is freed, since devm-managed resources are released after the
remove function completes.

This creates a potential race condition where an interrupt may occur
after the PPS source is unregistered but before the handler is removed,
possibly leading to a kernel panic.

To prevent this, switch from devm-managed IRQ registration to manual
management by using request_irq() and calling free_irq() explicitly in
the remove path before unregistering the PPS source. This ensures the
interrupt handler is safely removed before deactivating the PPS source.

Signed-off-by: Eliav Farber <farbere@amazon.com>
Link: https://lore.kernel.org/r/20250527053355.37185-1-farbere@amazon.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/pps/clients/pps-gpio.c b/drivers/pps/clients/pps-gpio.c
index 47d9891de368bd78bfbd1aa73c9d737dbcbe1f78..935da68610c701e6d9de53c667237f77438d7107 100644 (file)
--- a/drivers/pps/clients/pps-gpio.c
+++ b/drivers/pps/clients/pps-gpio.c
@@ -210,8 +210,8 @@ static int pps_gpio_probe(struct platform_device *pdev)
        }
 
        /* register IRQ interrupt handler */
-       ret = devm_request_irq(dev, data->irq, pps_gpio_irq_handler,
-                       get_irqf_trigger_flags(data), data->info.name, data);
+       ret = request_irq(data->irq, pps_gpio_irq_handler,
+                         get_irqf_trigger_flags(data), data->info.name, data);
        if (ret) {
                pps_unregister_source(data->pps);
                dev_err(dev, "failed to acquire IRQ %d\n", data->irq);
@@ -228,6 +228,7 @@ static void pps_gpio_remove(struct platform_device *pdev)
 {
        struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
 
+       free_irq(data->irq, data);
        pps_unregister_source(data->pps);
        timer_delete_sync(&data->echo_timer);
        /* reset echo pin in any case */