Re: [PATCH] mfd: viperboard: allocate I/O buffer separately

Octavian Purdila
2014-09-22T16:19:40Z

On Mon, Sep 22, 2014 at 7:08 PM, Johan Hovold <johan@kernel.org> wrote:
> On Mon, Sep 22, 2014 at 05:46:52PM +0300, 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@intel.com>
>> ---
>
> Change itself looks sane, although the driver's use of a shared buffer
> and relying on undocumented locking is a different story.
>
> However, you do more than your commit message claims below.
>
>> drivers/mfd/viperboard.c | 16 ++++++++++------
>> include/linux/mfd/viperboard.h | 2 +-
>> 2 files changed, 11 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/mfd/viperboard.c b/drivers/mfd/viperboard.c
>> index e00f534..d27c131 100644
>> --- a/drivers/mfd/viperboard.c
>> +++ b/drivers/mfd/viperboard.c
>> @@ -59,9 +59,13 @@ static int vprbrd_probe(struct usb_interface *interface,
>>
>> /* 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");
>
> Here you're also removing a redundant OOM message.
>
>> + if (vb == NULL)
>> 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);
>> @@ -103,10 +107,9 @@ static int vprbrd_probe(struct usb_interface *interface,
>> return 0;
>>
>> error:
>> - if (vb) {
>
> And cleaning up the error path.
>
>> - usb_put_dev(vb->usb_dev);
>> - kfree(vb);
>> - }
>> + usb_put_dev(vb->usb_dev);
>> + kfree(vb->buf);
>> + kfree(vb);
>>
>> return ret;
>> }
>
> Don't mix fixes and clean ups like this, but rather submit them as
> separate patches.
>

Fair enough. Is it OK to send all of the cleanups in a single separate patch?