From de5d7adb89367bbc87b4e5ce7afe7ae9bd86dc12 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
Date: Tue, 26 Jan 2021 17:58:31 +0100
Subject: [PATCH] amba: Fix resource leak for drivers without .remove
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Git-commit: de5d7adb89367bbc87b4e5ce7afe7ae9bd86dc12
Patch-mainline: v5.12-rc1
References: git-fixes

Consider an amba driver with a .probe but without a .remove callback (e.g.
pl061_gpio_driver). The function amba_probe() is called to bind a device
and so dev_pm_domain_attach() and others are called. As there is no remove
callback amba_remove() isn't called at unbind time however and so calling
dev_pm_domain_detach() is missed and the pm domain keeps active.

To fix this always use the core driver callbacks and handle missing amba
callbacks there. For probe refuse registration as a driver without probe
doesn't make sense.

Fixes: 7cfe249475fd ("ARM: AMBA: Add pclk support to AMBA bus infrastructure")
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210126165835.687514-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/amba/bus.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index ecc304149067..b5f5ca4e3f34 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -299,10 +299,11 @@ static int amba_remove(struct device *dev)
 {
 	struct amba_device *pcdev = to_amba_device(dev);
 	struct amba_driver *drv = to_amba_driver(dev->driver);
-	int ret;
+	int ret = 0;
 
 	pm_runtime_get_sync(dev);
-	ret = drv->remove(pcdev);
+	if (drv->remove)
+		ret = drv->remove(pcdev);
 	pm_runtime_put_noidle(dev);
 
 	/* Undo the runtime PM settings in amba_probe() */
@@ -319,7 +320,9 @@ static int amba_remove(struct device *dev)
 static void amba_shutdown(struct device *dev)
 {
 	struct amba_driver *drv = to_amba_driver(dev->driver);
-	drv->shutdown(to_amba_device(dev));
+
+	if (drv->shutdown)
+		drv->shutdown(to_amba_device(dev));
 }
 
 /**
@@ -332,12 +335,13 @@ static void amba_shutdown(struct device *dev)
  */
 int amba_driver_register(struct amba_driver *drv)
 {
-	drv->drv.bus = &amba_bustype;
+	if (!drv->probe)
+		return -EINVAL;
 
-#define SETFN(fn)	if (drv->fn) drv->drv.fn = amba_##fn
-	SETFN(probe);
-	SETFN(remove);
-	SETFN(shutdown);
+	drv->drv.bus = &amba_bustype;
+	drv->drv.probe = amba_probe;
+	drv->drv.remove = amba_remove;
+	drv->drv.shutdown = amba_shutdown;
 
 	return driver_register(&drv->drv);
 }
-- 
2.26.2