On Mon, 22 Sep 2014, Octavian Purdila wrote:
> 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@xxxxxxxxx>
> ---
> 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);
Can you obtain the 'struct device' first then use managed resources
(devm_*)?
> + 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);
Then you don't need this.
> 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);
Or this.
> 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;
> };
>
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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