[PATCH v1 1/2] mei: bus: simplify mei_cl_device_remove()

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 <redacted>
---
 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);
 

base-commit: 5c8fe583cce542aa0b84adc939ce85293de36e5e
-- 
2.29.2

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.

Signed-off-by: Uwe Kleine-König <redacted>
---
 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..6a455ebe4891 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

On 2/7/21 2:22 PM, Uwe Kleine-König wrote:

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.

Signed-off-by: Uwe Kleine-König <redacted>
---
 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 +---

Acked-by: Guenter Roeck <linux@roeck-us.net>

Hi "Uwe,

I love your patch! Yet something to improve:

[auto build test ERROR on 5c8fe583cce542aa0b84adc939ce85293de36e5e]

url:    https://github.com/0day-ci/linux/commits/Uwe-Kleine-K-nig/mei-bus-simplify-mei_cl_device_remove/20210208-062551
base:   5c8fe583cce542aa0b84adc939ce85293de36e5e
config: x86_64-randconfig-a001-20210208 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project c9439ca36342fb6013187d0a69aef92736951476)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/a53f4d8c3937ee9db8a6f6335e6d562648f651f7
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Uwe-Kleine-K-nig/mei-bus-simplify-mei_cl_device_remove/20210208-062551
        git checkout a53f4d8c3937ee9db8a6f6335e6d562648f651f7
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All errors (new ones prefixed by >>):

quoted

drivers/misc/mei/hdcp/mei_hdcp.c:860:56: error: expected ';' after expression

                   dev_warn(&cldev->dev, "mei_cldev_disable() failed\n")
                                                                        ^
                                                                        ;
   1 error generated.


vim +860 drivers/misc/mei/hdcp/mei_hdcp.c

   847	
   848	static void mei_hdcp_remove(struct mei_cl_device *cldev)
   849	{
   850		struct i915_hdcp_comp_master *comp_master =
   851							mei_cldev_get_drvdata(cldev);
   852		int ret;
   853	
   854		component_master_del(&cldev->dev, &mei_component_master_ops);
   855		kfree(comp_master);
   856		mei_cldev_set_drvdata(cldev, NULL);
   857	
   858		ret = mei_cldev_disable(cldev);
   859		if (ret)
 > 860			dev_warn(&cldev->dev, "mei_cldev_disable() failed\n")
   861	}
   862	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

Hi "Uwe,

I love your patch! Yet something to improve:

[auto build test ERROR on 5c8fe583cce542aa0b84adc939ce85293de36e5e]

url:    https://github.com/0day-ci/linux/commits/Uwe-Kleine-K-nig/mei-bus-simplify-mei_cl_device_remove/20210208-062551
base:   5c8fe583cce542aa0b84adc939ce85293de36e5e
config: i386-randconfig-r032-20210208 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/a53f4d8c3937ee9db8a6f6335e6d562648f651f7
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Uwe-Kleine-K-nig/mei-bus-simplify-mei_cl_device_remove/20210208-062551
        git checkout a53f4d8c3937ee9db8a6f6335e6d562648f651f7
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All errors (new ones prefixed by >>):

   drivers/misc/mei/hdcp/mei_hdcp.c: In function 'mei_hdcp_remove':

quoted

drivers/misc/mei/hdcp/mei_hdcp.c:861:1: error: expected ';' before '}' token

     861 | }
         | ^


vim +861 drivers/misc/mei/hdcp/mei_hdcp.c

64e9bbdd9588ad Ramalingam C     2019-02-21  847  
a53f4d8c3937ee Uwe Kleine-König 2021-02-07  848  static void mei_hdcp_remove(struct mei_cl_device *cldev)
64e9bbdd9588ad Ramalingam C     2019-02-21  849  {
fa301ad9fa8f6f Ramalingam C     2019-02-21  850  	struct i915_hdcp_comp_master *comp_master =
fa301ad9fa8f6f Ramalingam C     2019-02-21  851  						mei_cldev_get_drvdata(cldev);
a53f4d8c3937ee Uwe Kleine-König 2021-02-07  852  	int ret;
fa301ad9fa8f6f Ramalingam C     2019-02-21  853  
fa301ad9fa8f6f Ramalingam C     2019-02-21  854  	component_master_del(&cldev->dev, &mei_component_master_ops);
fa301ad9fa8f6f Ramalingam C     2019-02-21  855  	kfree(comp_master);
fa301ad9fa8f6f Ramalingam C     2019-02-21  856  	mei_cldev_set_drvdata(cldev, NULL);
fa301ad9fa8f6f Ramalingam C     2019-02-21  857  
a53f4d8c3937ee Uwe Kleine-König 2021-02-07  858  	ret = mei_cldev_disable(cldev);
a53f4d8c3937ee Uwe Kleine-König 2021-02-07  859  	if (ret)
a53f4d8c3937ee Uwe Kleine-König 2021-02-07  860  		dev_warn(&cldev->dev, "mei_cldev_disable() failed\n")
64e9bbdd9588ad Ramalingam C     2019-02-21 @861  }
64e9bbdd9588ad Ramalingam C     2019-02-21  862  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

Hi "Uwe,

I love your patch! Yet something to improve:

[auto build test ERROR on 5c8fe583cce542aa0b84adc939ce85293de36e5e]

url:    https://github.com/0day-ci/linux/commits/Uwe-Kleine-K-nig/mei-bus-simplify-mei_cl_device_remove/20210208-062551
base:   5c8fe583cce542aa0b84adc939ce85293de36e5e
config: i386-randconfig-s001-20210208 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-215-g0fb77bb6-dirty
        # https://github.com/0day-ci/linux/commit/a53f4d8c3937ee9db8a6f6335e6d562648f651f7
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Uwe-Kleine-K-nig/mei-bus-simplify-mei_cl_device_remove/20210208-062551
        git checkout a53f4d8c3937ee9db8a6f6335e6d562648f651f7
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All errors (new ones prefixed by >>):

   drivers/misc/mei/hdcp/mei_hdcp.c: In function 'mei_hdcp_remove':

quoted

drivers/misc/mei/hdcp/mei_hdcp.c:861:1: error: expected ';' before '}' token

     861 | }
         | ^


vim +861 drivers/misc/mei/hdcp/mei_hdcp.c

64e9bbdd9588ad Ramalingam C     2019-02-21  847  
a53f4d8c3937ee Uwe Kleine-König 2021-02-07  848  static void mei_hdcp_remove(struct mei_cl_device *cldev)
64e9bbdd9588ad Ramalingam C     2019-02-21  849  {
fa301ad9fa8f6f Ramalingam C     2019-02-21  850  	struct i915_hdcp_comp_master *comp_master =
fa301ad9fa8f6f Ramalingam C     2019-02-21  851  						mei_cldev_get_drvdata(cldev);
a53f4d8c3937ee Uwe Kleine-König 2021-02-07  852  	int ret;
fa301ad9fa8f6f Ramalingam C     2019-02-21  853  
fa301ad9fa8f6f Ramalingam C     2019-02-21  854  	component_master_del(&cldev->dev, &mei_component_master_ops);
fa301ad9fa8f6f Ramalingam C     2019-02-21  855  	kfree(comp_master);
fa301ad9fa8f6f Ramalingam C     2019-02-21  856  	mei_cldev_set_drvdata(cldev, NULL);
fa301ad9fa8f6f Ramalingam C     2019-02-21  857  
a53f4d8c3937ee Uwe Kleine-König 2021-02-07  858  	ret = mei_cldev_disable(cldev);
a53f4d8c3937ee Uwe Kleine-König 2021-02-07  859  	if (ret)
a53f4d8c3937ee Uwe Kleine-König 2021-02-07  860  		dev_warn(&cldev->dev, "mei_cldev_disable() failed\n")
64e9bbdd9588ad Ramalingam C     2019-02-21 @861  }
64e9bbdd9588ad Ramalingam C     2019-02-21  862  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org