[PATCH v3 0/3] mfd: viperboard: fix cache line sharing and cleanups

[PATCH v3 0/3] mfd: viperboard: fix cache line sharing and cleanups

[Octavian Purdila]

Changes since v2:
 
 * switch to using devm_ allocation

 * remove unused platform_device

Changes since v1:

 * split cache sharing fix and cleanups into separate patches


Octavian Purdila (3):
  mfd: viperboard: allocate I/O buffer separately
  mfd: viperboard: switch to devm_ allocation
  mfd: viperboard: remove unused platform_device

 drivers/mfd/viperboard.c       | 19 +++++++++----------
 include/linux/mfd/viperboard.h |  3 +--
 2 files changed, 10 insertions(+), 12 deletions(-)

-- 
1.9.1

[PATCH v3 1/3] mfd: viperboard: allocate I/O buffer separately

[Octavian Purdila]

Currently the I/O buffer is allocated part of the device status
structure, potentially sharing the same cache line with other members
in this structure.

Allocate the buffer separately, to avoid the I/O operations corrupting
the device status structure due to cache line sharing.

Compiled tested only as I don't have access to hardware.

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
---
 drivers/mfd/viperboard.c       | 8 ++++++++
 include/linux/mfd/viperboard.h | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
index e00f534..5f62f4e 100644
--- a/drivers/mfd/viperboard.c
+++ b/drivers/mfd/viperboard.c
@@ -64,6 +64,12 @@ static int vprbrd_probe(struct usb_interface *interface,
 		return -ENOMEM;
 	}
 
+	vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL);
+	if (vb->buf == NULL) {
+		ret = -ENOMEM;
+		goto error;
+	}
+
 	mutex_init(&vb->lock);
 
 	vb->usb_dev = usb_get_dev(interface_to_usbdev(interface));
@@ -105,6 +111,7 @@ static int vprbrd_probe(struct usb_interface *interface,
 error:
 	if (vb) {
 		usb_put_dev(vb->usb_dev);
+		kfree(vb->buf);
 		kfree(vb);
 	}
 
@@ -118,6 +125,7 @@ static void vprbrd_disconnect(struct usb_interface *interface)
 	mfd_remove_devices(&interface->dev);
 	usb_set_intfdata(interface, NULL);
 	usb_put_dev(vb->usb_dev);
+	kfree(vb->buf);
 	kfree(vb);
 
 	dev_dbg(&interface->dev, "disconnected\n");
diff --git a/include/linux/mfd/viperboard.h b/include/linux/mfd/viperboard.h
index 1934528..af928d0 100644
--- a/include/linux/mfd/viperboard.h
+++ b/include/linux/mfd/viperboard.h
@@ -103,7 +103,7 @@ struct vprbrd_i2c_addr_msg {
 struct vprbrd {
 	struct usb_device *usb_dev; /* the usb device for this device */
 	struct mutex lock;
-	u8 buf[sizeof(struct vprbrd_i2c_write_msg)];
+	u8 *buf;
 	struct platform_device pdev;
 };
 
-- 
1.9.1

[PATCH v3 2/3] mfd: viperboard: switch to devm_ allocation

[Octavian Purdila]

Switch to using devm_ allocation to simplify the error path. Also
remove a redundant OOM error message.

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
---
 drivers/mfd/viperboard.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
index 5f62f4e..57fac1d 100644
--- a/drivers/mfd/viperboard.c
+++ b/drivers/mfd/viperboard.c
@@ -53,18 +53,16 @@ static int vprbrd_probe(struct usb_interface *interface,
 			      const struct usb_device_id *id)
 {
 	struct vprbrd *vb;
-
 	u16 version = 0;
 	int pipe, ret;
 
 	/* allocate memory for our device state and initialize it */
-	vb = kzalloc(sizeof(*vb), GFP_KERNEL);
-	if (vb == NULL) {
-		dev_err(&interface->dev, "Out of memory\n");
+	vb = devm_kzalloc(&interface->dev, sizeof(*vb), GFP_KERNEL);
+	if (vb == NULL)
 		return -ENOMEM;
-	}
 
-	vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL);
+	vb->buf = devm_kzalloc(&interface->dev,
+			       sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL);
 	if (vb->buf == NULL) {
 		ret = -ENOMEM;
 		goto error;
@@ -109,11 +107,7 @@ static int vprbrd_probe(struct usb_interface *interface,
 	return 0;
 
 error:
-	if (vb) {
-		usb_put_dev(vb->usb_dev);
-		kfree(vb->buf);
-		kfree(vb);
-	}
+	usb_put_dev(vb->usb_dev);
 
 	return ret;
 }
@@ -125,8 +119,6 @@ static void vprbrd_disconnect(struct usb_interface *interface)
 	mfd_remove_devices(&interface->dev);
 	usb_set_intfdata(interface, NULL);
 	usb_put_dev(vb->usb_dev);
-	kfree(vb->buf);
-	kfree(vb);
 
 	dev_dbg(&interface->dev, "disconnected\n");
 }
-- 
1.9.1

[PATCH v3 3/3] mfd: viperboard: remove unused platform_device

[Octavian Purdila]

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
---
 drivers/mfd/viperboard.c       | 1 -
 include/linux/mfd/viperboard.h | 1 -
 2 files changed, 2 deletions(-)

diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
index 57fac1d..1e7c316 100644
--- a/drivers/mfd/viperboard.c
+++ b/drivers/mfd/viperboard.c
@@ -74,7 +74,6 @@ static int vprbrd_probe(struct usb_interface *interface,
 
 	/* save our data pointer in this interface device */
 	usb_set_intfdata(interface, vb);
-	dev_set_drvdata(&vb->pdev.dev, vb);
 
 	/* get version information, major first, minor then */
 	pipe = usb_rcvctrlpipe(vb->usb_dev, 0);
diff --git a/include/linux/mfd/viperboard.h b/include/linux/mfd/viperboard.h
index af928d0..afc14ed 100644
--- a/include/linux/mfd/viperboard.h
+++ b/include/linux/mfd/viperboard.h
@@ -104,7 +104,6 @@ struct vprbrd {
 	struct usb_device *usb_dev; /* the usb device for this device */
 	struct mutex lock;
 	u8 *buf;
-	struct platform_device pdev;
 };
 
 #endif /* __MFD_VIPERBOARD_H__ */
-- 
1.9.1

Re: [PATCH v3 2/3] mfd: viperboard: switch to devm_ allocation

[Johan Hovold]

On Thu, Sep 25, 2014 at 05:43:16PM +0300, Octavian Purdila wrote:
> Switch to using devm_ allocation to simplify the error path. Also
> remove a redundant OOM error message.
> 
> Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
> ---
>  drivers/mfd/viperboard.c | 18 +++++-------------
>  1 file changed, 5 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
> index 5f62f4e..57fac1d 100644
> --- a/drivers/mfd/viperboard.c
> +++ b/drivers/mfd/viperboard.c
> @@ -53,18 +53,16 @@ static int vprbrd_probe(struct usb_interface *interface,
>  			      const struct usb_device_id *id)
>  {
>  	struct vprbrd *vb;
> -

Don't include random whitespace changes in your patches.

>  	u16 version = 0;
>  	int pipe, ret;
>  
>  	/* allocate memory for our device state and initialize it */
> -	vb = kzalloc(sizeof(*vb), GFP_KERNEL);
> -	if (vb == NULL) {
> -		dev_err(&interface->dev, "Out of memory\n");
> +	vb = devm_kzalloc(&interface->dev, sizeof(*vb), GFP_KERNEL);
> +	if (vb == NULL)
>  		return -ENOMEM;
> -	}
>  
> -	vb->buf = kzalloc(sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL);
> +	vb->buf = devm_kzalloc(&interface->dev,
> +			       sizeof(struct vprbrd_i2c_write_msg), GFP_KERNEL);
>  	if (vb->buf == NULL) {
>  		ret = -ENOMEM;
>  		goto error;

You should just return -ENOMEM here.

> @@ -109,11 +107,7 @@ static int vprbrd_probe(struct usb_interface *interface,
>  	return 0;
>  
>  error:
> -	if (vb) {
> -		usb_put_dev(vb->usb_dev);
> -		kfree(vb->buf);
> -		kfree(vb);
> -	}
> +	usb_put_dev(vb->usb_dev);
>  
>  	return ret;
>  }
> @@ -125,8 +119,6 @@ static void vprbrd_disconnect(struct usb_interface *interface)
>  	mfd_remove_devices(&interface->dev);
>  	usb_set_intfdata(interface, NULL);
>  	usb_put_dev(vb->usb_dev);
> -	kfree(vb->buf);
> -	kfree(vb);
>  
>  	dev_dbg(&interface->dev, "disconnected\n");
>  }

Johan

Re: [PATCH v3 3/3] mfd: viperboard: remove unused platform_device

[Johan Hovold]

On Thu, Sep 25, 2014 at 05:43:17PM +0300, Octavian Purdila wrote:

Where's the commit message body?

> Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
> ---
>  drivers/mfd/viperboard.c       | 1 -
>  include/linux/mfd/viperboard.h | 1 -
>  2 files changed, 2 deletions(-)
> 
> diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
> index 57fac1d..1e7c316 100644
> --- a/drivers/mfd/viperboard.c
> +++ b/drivers/mfd/viperboard.c
> @@ -74,7 +74,6 @@ static int vprbrd_probe(struct usb_interface *interface,
>  
>  	/* save our data pointer in this interface device */
>  	usb_set_intfdata(interface, vb);
> -	dev_set_drvdata(&vb->pdev.dev, vb);

This looks ok, as the subdrivers are accessing the driver data via the
usb-interface (their parent) device.

You verified that too, right?

>  
>  	/* get version information, major first, minor then */
>  	pipe = usb_rcvctrlpipe(vb->usb_dev, 0);
> diff --git a/include/linux/mfd/viperboard.h b/include/linux/mfd/viperboard.h
> index af928d0..afc14ed 100644
> --- a/include/linux/mfd/viperboard.h
> +++ b/include/linux/mfd/viperboard.h
> @@ -104,7 +104,6 @@ struct vprbrd {
>  	struct usb_device *usb_dev; /* the usb device for this device */
>  	struct mutex lock;
>  	u8 *buf;
> -	struct platform_device pdev;
>  };
>  
>  #endif /* __MFD_VIPERBOARD_H__ */

Still feels like the kind of clean up that should have a Tested-by.

Johan

Re: [PATCH v3 3/3] mfd: viperboard: remove unused platform_device

[Octavian Purdila]

On Thu, Sep 25, 2014 at 6:07 PM, Johan Hovold <johan@kernel.org> wrote:
> On Thu, Sep 25, 2014 at 05:43:17PM +0300, Octavian Purdila wrote:
>
> Where's the commit message body?
>
>> Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
>> ---
>>  drivers/mfd/viperboard.c       | 1 -
>>  include/linux/mfd/viperboard.h | 1 -
>>  2 files changed, 2 deletions(-)
>>
>> diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
>> index 57fac1d..1e7c316 100644
>> --- a/drivers/mfd/viperboard.c
>> +++ b/drivers/mfd/viperboard.c
>> @@ -74,7 +74,6 @@ static int vprbrd_probe(struct usb_interface *interface,
>>
>>       /* save our data pointer in this interface device */
>>       usb_set_intfdata(interface, vb);
>> -     dev_set_drvdata(&vb->pdev.dev, vb);
>
> This looks ok, as the subdrivers are accessing the driver data via the
> usb-interface (their parent) device.
>
> You verified that too, right?

Yes, I checked that the pdev field of struct vpbrd is not used in the
rest of the drivers.

>
>>
>>       /* get version information, major first, minor then */
>>       pipe = usb_rcvctrlpipe(vb->usb_dev, 0);
>> diff --git a/include/linux/mfd/viperboard.h b/include/linux/mfd/viperboard.h
>> index af928d0..afc14ed 100644
>> --- a/include/linux/mfd/viperboard.h
>> +++ b/include/linux/mfd/viperboard.h
>> @@ -104,7 +104,6 @@ struct vprbrd {
>>       struct usb_device *usb_dev; /* the usb device for this device */
>>       struct mutex lock;
>>       u8 *buf;
>> -     struct platform_device pdev;
>>  };
>>
>>  #endif /* __MFD_VIPERBOARD_H__ */
>
> Still feels like the kind of clean up that should have a Tested-by.
>

Unfortunately I do not have access to hardware to test.

Re: [PATCH v3 3/3] mfd: viperboard: remove unused platform_device

[Johan Hovold]

On Thu, Sep 25, 2014 at 06:29:48PM +0300, Octavian Purdila wrote:
> On Thu, Sep 25, 2014 at 6:07 PM, Johan Hovold <johan@kernel.org> wrote:

> > Still feels like the kind of clean up that should have a Tested-by.
> 
> Unfortunately I do not have access to hardware to test.

On second thought, compile-testing should be enough. But please add a
proper commit message.

Johan