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* [PATCH 1/2] i3c: Handle drivers without probe or remove callback
@ 2021-01-28  9:10 Uwe Kleine-König
  2021-01-28  9:10 ` [PATCH 2/2] i3c: Make remove callback return void Uwe Kleine-König
  2021-02-01 23:17 ` [PATCH 1/2] i3c: Handle drivers without probe or remove callback Alexandre Belloni
  0 siblings, 2 replies; 4+ messages in thread
From: Uwe Kleine-König @ 2021-01-28  9:10 UTC (permalink / raw)
  To: Alexandre Belloni; +Cc: Greg Kroah-Hartman, linux-i3c, linux-kernel, kernel

A registered driver without a probe callback doesn't make sense, so
refuse to register such a driver. (Otherwise i3c_device_probe() yields a
NULL pointer exception.)

A driver without remove is possible, e.g. when all resources are freed
using devm callbacks. So guard the call to driver->remove by a check
for being non-NULL.

Note that the only in-tree i3c driver
(drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_i3c.c) doesn't have a remove
callback.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/i3c/device.c |  5 +++++
 drivers/i3c/master.c | 10 ++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/i3c/device.c b/drivers/i3c/device.c
index bb8e60dff988..e92d3e9a52bd 100644
--- a/drivers/i3c/device.c
+++ b/drivers/i3c/device.c
@@ -262,6 +262,11 @@ int i3c_driver_register_with_owner(struct i3c_driver *drv, struct module *owner)
 	drv->driver.owner = owner;
 	drv->driver.bus = &i3c_bus_type;
 
+	if (!drv->probe) {
+		pr_err("Trying to register an i3c driver without probe callback\n");
+		return -EINVAL;
+	}
+
 	return driver_register(&drv->driver);
 }
 EXPORT_SYMBOL_GPL(i3c_driver_register_with_owner);
diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index b61bf53ec07a..57a4f699eb8d 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -326,11 +326,13 @@ static int i3c_device_remove(struct device *dev)
 {
 	struct i3c_device *i3cdev = dev_to_i3cdev(dev);
 	struct i3c_driver *driver = drv_to_i3cdrv(dev->driver);
-	int ret;
+	int ret = 0;
 
-	ret = driver->remove(i3cdev);
-	if (ret)
-		return ret;
+	if (driver->remove) {
+		ret = driver->remove(i3cdev);
+		if (ret)
+			return ret;
+	}
 
 	i3c_device_free_ibi(i3cdev);
 
-- 
2.29.2


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^ permalink raw reply related	[flat|nested] 4+ messages in thread
* [PATCH 2/2] i3c: Make remove callback return void
  2021-01-28  9:10 [PATCH 1/2] i3c: Handle drivers without probe or remove callback Uwe Kleine-König
@ 2021-01-28  9:10 ` Uwe Kleine-König
  2021-02-01 23:17 ` [PATCH 1/2] i3c: Handle drivers without probe or remove callback Alexandre Belloni
  1 sibling, 0 replies; 4+ messages in thread
From: Uwe Kleine-König @ 2021-01-28  9:10 UTC (permalink / raw)
  To: Alexandre Belloni; +Cc: Greg Kroah-Hartman, linux-i3c, linux-kernel, kernel

The driver core ignores the return value of struct bus_type::remove()
because there is only little that can be done. To simplify the quest to
make this function return void, let struct i3c_driver::remove() return
void, too. This makes it obvious that returning an error code is
a bad idea and future driver authors cannot get that wrong.

Up to now there are no drivers with a remove callback, so there is no
need to adapt drivers.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/i3c/master.c       | 10 +++-------
 include/linux/i3c/device.h |  2 +-
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index 57a4f699eb8d..f8e9b7305c13 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -326,17 +326,13 @@ static int i3c_device_remove(struct device *dev)
 {
 	struct i3c_device *i3cdev = dev_to_i3cdev(dev);
 	struct i3c_driver *driver = drv_to_i3cdrv(dev->driver);
-	int ret = 0;
 
-	if (driver->remove) {
-		ret = driver->remove(i3cdev);
-		if (ret)
-			return ret;
-	}
+	if (driver->remove)
+		driver->remove(i3cdev);
 
 	i3c_device_free_ibi(i3cdev);
 
-	return ret;
+	return 0;
 }
 
 struct bus_type i3c_bus_type = {
diff --git a/include/linux/i3c/device.h b/include/linux/i3c/device.h
index de102e4418ab..8242e13e7b0b 100644
--- a/include/linux/i3c/device.h
+++ b/include/linux/i3c/device.h
@@ -176,7 +176,7 @@ struct i3c_device;
 struct i3c_driver {
 	struct device_driver driver;
 	int (*probe)(struct i3c_device *dev);
-	int (*remove)(struct i3c_device *dev);
+	void (*remove)(struct i3c_device *dev);
 	const struct i3c_device_id *id_table;
 };
 
-- 
2.29.2


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^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH 1/2] i3c: Handle drivers without probe or remove callback
  2021-01-28  9:10 [PATCH 1/2] i3c: Handle drivers without probe or remove callback Uwe Kleine-König
  2021-01-28  9:10 ` [PATCH 2/2] i3c: Make remove callback return void Uwe Kleine-König
@ 2021-02-01 23:17 ` Alexandre Belloni
  1 sibling, 0 replies; 4+ messages in thread
From: Alexandre Belloni @ 2021-02-01 23:17 UTC (permalink / raw)
  To: Uwe Kleine-König
  Cc: Greg Kroah-Hartman, Alexandre Belloni, linux-i3c, linux-kernel, kernel

On Thu, 28 Jan 2021 10:10:47 +0100, Uwe Kleine-König wrote:
> A registered driver without a probe callback doesn't make sense, so
> refuse to register such a driver. (Otherwise i3c_device_probe() yields a
> NULL pointer exception.)
> 
> A driver without remove is possible, e.g. when all resources are freed
> using devm callbacks. So guard the call to driver->remove by a check
> for being non-NULL.
> 
> [...]

Applied, thanks!

[1/2] i3c: Handle drivers without probe or remove callback
      commit: 7456fea589c6ad3422b0c188871ae80e1d307737
[2/2] i3c: Make remove callback return void
      commit: dd9267034c0e364b49261c3e0070b863286d1242

Best regards,
-- 
Alexandre Belloni <alexandre.belloni@bootlin.com>

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^ permalink raw reply	[flat|nested] 4+ messages in thread
* [PATCH 1/2] i3c: Handle drivers without probe or remove callback
@ 2021-01-28  9:10 Uwe Kleine-König
  0 siblings, 0 replies; 4+ messages in thread
From: Uwe Kleine-König @ 2021-01-28  9:10 UTC (permalink / raw)
  To: Alexandre Belloni; +Cc: Greg Kroah-Hartman, linux-i3c, linux-kernel

A registered driver without a probe callback doesn't make sense, so
refuse to register such a driver. (Otherwise i3c_device_probe() yields a
NULL pointer exception.)

A driver without remove is possible, e.g. when all resources are freed
using devm callbacks. So guard the call to driver->remove by a check
for being non-NULL.

Note that the only in-tree i3c driver
(drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_i3c.c) doesn't have a remove
callback.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/i3c/device.c |  5 +++++
 drivers/i3c/master.c | 10 ++++++----
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/i3c/device.c b/drivers/i3c/device.c
index bb8e60dff988..e92d3e9a52bd 100644
--- a/drivers/i3c/device.c
+++ b/drivers/i3c/device.c
@@ -262,6 +262,11 @@ int i3c_driver_register_with_owner(struct i3c_driver *drv, struct module *owner)
 	drv->driver.owner = owner;
 	drv->driver.bus = &i3c_bus_type;
 
+	if (!drv->probe) {
+		pr_err("Trying to register an i3c driver without probe callback\n");
+		return -EINVAL;
+	}
+
 	return driver_register(&drv->driver);
 }
 EXPORT_SYMBOL_GPL(i3c_driver_register_with_owner);
diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index b61bf53ec07a..57a4f699eb8d 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -326,11 +326,13 @@ static int i3c_device_remove(struct device *dev)
 {
 	struct i3c_device *i3cdev = dev_to_i3cdev(dev);
 	struct i3c_driver *driver = drv_to_i3cdrv(dev->driver);
-	int ret;
+	int ret = 0;
 
-	ret = driver->remove(i3cdev);
-	if (ret)
-		return ret;
+	if (driver->remove) {
+		ret = driver->remove(i3cdev);
+		if (ret)
+			return ret;
+	}
 
 	i3c_device_free_ibi(i3cdev);
 
-- 
2.29.2


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^ permalink raw reply related	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-02-01 23:17 UTC | newest]

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2021-01-28  9:10 [PATCH 1/2] i3c: Handle drivers without probe or remove callback Uwe Kleine-König
2021-01-28  9:10 ` [PATCH 2/2] i3c: Make remove callback return void Uwe Kleine-König
2021-02-01 23:17 ` [PATCH 1/2] i3c: Handle drivers without probe or remove callback Alexandre Belloni
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