linux-kernel - [PATCH AUTOSEL 5.10 33/34] gpio: grgpio: Fix device removing

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Message-Id: <20220628022241.595835-33-sashal@kernel.org>
Date:   Mon, 27 Jun 2022 22:22:40 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Sasha Levin <sashal@...nel.org>, linus.walleij@...aro.org,
        linux-gpio@...r.kernel.org
Subject: [PATCH AUTOSEL 5.10 33/34] gpio: grgpio: Fix device removing

From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>

[ Upstream commit c1c2a15c2b5379ea8e44dcdcc298e3de42076ba0 ]

If a platform device's remove callback returns non-zero, the device core
emits a warning and still removes the device and calls the devm cleanup
callbacks.

So it's not save to not unregister the gpiochip because on the next request
to a GPIO the driver accesses kfree()'d memory. Also if an IRQ triggers,
the freed memory is accessed.

Instead rely on the GPIO framework to ensure that after gpiochip_remove()
all GPIOs are freed and so the corresponding IRQs are unmapped.

This is a preparation for making platform remove callbacks return void.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
Signed-off-by: Bartosz Golaszewski <brgl@...ev.pl>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpio/gpio-grgpio.c | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/drivers/gpio/gpio-grgpio.c b/drivers/gpio/gpio-grgpio.c
index f954359c9544..46f6158d1c71 100644
--- a/drivers/gpio/gpio-grgpio.c
+++ b/drivers/gpio/gpio-grgpio.c
@@ -435,25 +435,13 @@ static int grgpio_probe(struct platform_device *ofdev)
 static int grgpio_remove(struct platform_device *ofdev)
 {
 	struct grgpio_priv *priv = platform_get_drvdata(ofdev);
-	int i;
-	int ret = 0;
-
-	if (priv->domain) {
-		for (i = 0; i < GRGPIO_MAX_NGPIO; i++) {
-			if (priv->uirqs[i].refcnt != 0) {
-				ret = -EBUSY;
-				goto out;
-			}
-		}
-	}
 
 	gpiochip_remove(&priv->gc);
 
 	if (priv->domain)
 		irq_domain_remove(priv->domain);
 
-out:
-	return ret;
+	return 0;
 }
 
 static const struct of_device_id grgpio_match[] = {
-- 
2.35.1