[PATCH v2 0/2] mei: bus: Some cleanups

[PATCH v2 0/2] mei: bus: Some cleanups

[Uwe Kleine-König]

Hello,

changes since v1:
 - Added a missing ; found by kernel test robot, thanks
 - Added an Ack for Guenter

rangediff can be found below.

Uwe Kleine-König (2):
  mei: bus: simplify mei_cl_device_remove()
  mei: bus: change remove callback to return void

 drivers/misc/mei/bus.c           | 11 +++--------
 drivers/misc/mei/hdcp/mei_hdcp.c |  7 +++++--
 drivers/nfc/microread/mei.c      |  4 +---
 drivers/nfc/pn544/mei.c          |  4 +---
 drivers/watchdog/mei_wdt.c       |  4 +---
 include/linux/mei_cl_bus.h       |  2 +-
 6 files changed, 12 insertions(+), 20 deletions(-)

Range-diff against v1:
-:  ------------ > 1:  86b2bf521a84 mei: bus: simplify mei_cl_device_remove()
1:  10a3dfb49d4f ! 2:  807117116ccb mei: bus: change remove callback to return void
    @@ Commit message
         return an error value is modified to emit an explicit warning in the error
         case.
     
    +    Acked-by: Guenter Roeck <linux@roeck-us.net>
         Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
     
      ## drivers/misc/mei/bus.c ##
    @@ drivers/misc/mei/hdcp/mei_hdcp.c: static int mei_hdcp_probe(struct mei_cl_device
     -	return mei_cldev_disable(cldev);
     +	ret = mei_cldev_disable(cldev);
     +	if (ret)
    -+		dev_warn(&cldev->dev, "mei_cldev_disable() failed\n")
    ++		dev_warn(&cldev->dev, "mei_cldev_disable() failed\n");
      }
      
      #define MEI_UUID_HDCP GUID_INIT(0xB638AB7E, 0x94E2, 0x4EA2, 0xA5, \

base-commit: 5c8fe583cce542aa0b84adc939ce85293de36e5e
-- 
2.29.2

[PATCH v2 1/2] mei: bus: simplify mei_cl_device_remove()

[Uwe Kleine-König]

The driver core only calls a bus' remove function when there is actually
a driver and a device. So drop the needless check and assign cldrv earlier.

(Side note: The check for cldev being non-NULL is broken anyhow, because
to_mei_cl_device() is a wrapper around container_of() for a member that is
not the first one. So cldev only can become NULL if dev is (void *)0xc
(for archs with 32 bit pointers) or (void *)0x18 (for archs with 64 bit
pointers).)

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
---
 drivers/misc/mei/bus.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index 2907db260fba..50d617e7467e 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -878,13 +878,9 @@ static int mei_cl_device_probe(struct device *dev)
 static int mei_cl_device_remove(struct device *dev)
 {
 	struct mei_cl_device *cldev = to_mei_cl_device(dev);
-	struct mei_cl_driver *cldrv;
+	struct mei_cl_driver *cldrv = to_mei_cl_driver(dev->driver);
 	int ret = 0;
 
-	if (!cldev || !dev->driver)
-		return 0;
-
-	cldrv = to_mei_cl_driver(dev->driver);
 	if (cldrv->remove)
 		ret = cldrv->remove(cldev);
 
-- 
2.29.2

[PATCH v2 2/2] mei: bus: change remove callback to return void

[Uwe Kleine-König]

The driver core ignores the return value of mei_cl_device_remove() so
passing an error value doesn't solve any problem. As most mei drivers'
remove callbacks return 0 unconditionally and returning a different value
doesn't have any effect, change this prototype to return void and return 0
unconditionally in mei_cl_device_remove(). The only driver that could
return an error value is modified to emit an explicit warning in the error
case.

Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
---
 drivers/misc/mei/bus.c           | 5 ++---
 drivers/misc/mei/hdcp/mei_hdcp.c | 7 +++++--
 drivers/nfc/microread/mei.c      | 4 +---
 drivers/nfc/pn544/mei.c          | 4 +---
 drivers/watchdog/mei_wdt.c       | 4 +---
 include/linux/mei_cl_bus.h       | 2 +-
 6 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index 50d617e7467e..54dddae46705 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -879,17 +879,16 @@ static int mei_cl_device_remove(struct device *dev)
 {
 	struct mei_cl_device *cldev = to_mei_cl_device(dev);
 	struct mei_cl_driver *cldrv = to_mei_cl_driver(dev->driver);
-	int ret = 0;
 
 	if (cldrv->remove)
-		ret = cldrv->remove(cldev);
+		cldrv->remove(cldev);
 
 	mei_cldev_unregister_callbacks(cldev);
 
 	mei_cl_bus_module_put(cldev);
 	module_put(THIS_MODULE);
 
-	return ret;
+	return 0;
 }
 
 static ssize_t name_show(struct device *dev, struct device_attribute *a,
diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c b/drivers/misc/mei/hdcp/mei_hdcp.c
index 9ae9669e46ea..8447ad4b7d47 100644
--- a/drivers/misc/mei/hdcp/mei_hdcp.c
+++ b/drivers/misc/mei/hdcp/mei_hdcp.c
@@ -845,16 +845,19 @@ static int mei_hdcp_probe(struct mei_cl_device *cldev,
 	return ret;
 }
 
-static int mei_hdcp_remove(struct mei_cl_device *cldev)
+static void mei_hdcp_remove(struct mei_cl_device *cldev)
 {
 	struct i915_hdcp_comp_master *comp_master =
 						mei_cldev_get_drvdata(cldev);
+	int ret;
 
 	component_master_del(&cldev->dev, &mei_component_master_ops);
 	kfree(comp_master);
 	mei_cldev_set_drvdata(cldev, NULL);
 
-	return mei_cldev_disable(cldev);
+	ret = mei_cldev_disable(cldev);
+	if (ret)
+		dev_warn(&cldev->dev, "mei_cldev_disable() failed\n");
 }
 
 #define MEI_UUID_HDCP GUID_INIT(0xB638AB7E, 0x94E2, 0x4EA2, 0xA5, \
diff --git a/drivers/nfc/microread/mei.c b/drivers/nfc/microread/mei.c
index 5dad8847a9b3..8fa7771085eb 100644
--- a/drivers/nfc/microread/mei.c
+++ b/drivers/nfc/microread/mei.c
@@ -44,15 +44,13 @@ static int microread_mei_probe(struct mei_cl_device *cldev,
 	return 0;
 }
 
-static int microread_mei_remove(struct mei_cl_device *cldev)
+static void microread_mei_remove(struct mei_cl_device *cldev)
 {
 	struct nfc_mei_phy *phy = mei_cldev_get_drvdata(cldev);
 
 	microread_remove(phy->hdev);
 
 	nfc_mei_phy_free(phy);
-
-	return 0;
 }
 
 static struct mei_cl_device_id microread_mei_tbl[] = {
diff --git a/drivers/nfc/pn544/mei.c b/drivers/nfc/pn544/mei.c
index 579bc599f545..5c10aac085a4 100644
--- a/drivers/nfc/pn544/mei.c
+++ b/drivers/nfc/pn544/mei.c
@@ -42,7 +42,7 @@ static int pn544_mei_probe(struct mei_cl_device *cldev,
 	return 0;
 }
 
-static int pn544_mei_remove(struct mei_cl_device *cldev)
+static void pn544_mei_remove(struct mei_cl_device *cldev)
 {
 	struct nfc_mei_phy *phy = mei_cldev_get_drvdata(cldev);
 
@@ -51,8 +51,6 @@ static int pn544_mei_remove(struct mei_cl_device *cldev)
 	pn544_hci_remove(phy->hdev);
 
 	nfc_mei_phy_free(phy);
-
-	return 0;
 }
 
 static struct mei_cl_device_id pn544_mei_tbl[] = {
diff --git a/drivers/watchdog/mei_wdt.c b/drivers/watchdog/mei_wdt.c
index 5391bf3e6b11..53165e49c298 100644
--- a/drivers/watchdog/mei_wdt.c
+++ b/drivers/watchdog/mei_wdt.c
@@ -619,7 +619,7 @@ static int mei_wdt_probe(struct mei_cl_device *cldev,
 	return ret;
 }
 
-static int mei_wdt_remove(struct mei_cl_device *cldev)
+static void mei_wdt_remove(struct mei_cl_device *cldev)
 {
 	struct mei_wdt *wdt = mei_cldev_get_drvdata(cldev);
 
@@ -636,8 +636,6 @@ static int mei_wdt_remove(struct mei_cl_device *cldev)
 	dbgfs_unregister(wdt);
 
 	kfree(wdt);
-
-	return 0;
 }
 
 #define MEI_UUID_WD UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, \
diff --git a/include/linux/mei_cl_bus.h b/include/linux/mei_cl_bus.h
index 959ad7d850b4..07f5ef8fc456 100644
--- a/include/linux/mei_cl_bus.h
+++ b/include/linux/mei_cl_bus.h
@@ -68,7 +68,7 @@ struct mei_cl_driver {
 
 	int (*probe)(struct mei_cl_device *cldev,
 		     const struct mei_cl_device_id *id);
-	int (*remove)(struct mei_cl_device *cldev);
+	void (*remove)(struct mei_cl_device *cldev);
 };
 
 int __mei_cldev_driver_register(struct mei_cl_driver *cldrv,
-- 
2.29.2

Re: [PATCH v2 1/2] mei: bus: simplify mei_cl_device_remove()

[Greg Kroah-Hartman]

On Mon, Feb 08, 2021 at 08:37:04AM +0100, Uwe Kleine-König wrote:
> The driver core only calls a bus' remove function when there is actually
> a driver and a device. So drop the needless check and assign cldrv earlier.
> 
> (Side note: The check for cldev being non-NULL is broken anyhow, because
> to_mei_cl_device() is a wrapper around container_of() for a member that is
> not the first one. So cldev only can become NULL if dev is (void *)0xc
> (for archs with 32 bit pointers) or (void *)0x18 (for archs with 64 bit
> pointers).)
> 
> Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
> ---
>  drivers/misc/mei/bus.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
> index 2907db260fba..50d617e7467e 100644
> --- a/drivers/misc/mei/bus.c
> +++ b/drivers/misc/mei/bus.c
> @@ -878,13 +878,9 @@ static int mei_cl_device_probe(struct device *dev)
>  static int mei_cl_device_remove(struct device *dev)
>  {
>  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
> -	struct mei_cl_driver *cldrv;
> +	struct mei_cl_driver *cldrv = to_mei_cl_driver(dev->driver);
>  	int ret = 0;
>  
> -	if (!cldev || !dev->driver)

Yes, anyone checking that the results of a container_of() wrapper can be
NULL is not checking anything at all :)

thanks for the cleanups, I'll go queue them up.

greg k-h