linux-kernel - Re: [PATCH] NFC: port100: Introduce the use of function put_unaligned

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Date:	Wed, 24 Dec 2014 08:05:22 +0530
From:	Vaishali Thakkar <vthakkar1994@...il.com>
To:	Arend van Spriel <arend@...adcom.com>
Cc:	linux-wireless@...r.kernel.org, lauro.venancio@...nbossa.org,
	aloisio.almeida@...nbossa.org, sameo@...ux.intel.com,
	linux-kernel@...r.kernel.org,
	Johannes Berg <johannes.berg@...el.com>
Subject: Re: [PATCH] NFC: port100: Introduce the use of function put_unaligned_le16

On Wed, Dec 24, 2014 at 12:54 AM, Arend van Spriel <arend@...adcom.com> wrote:
> On 12/23/14 16:27, Vaishali Thakkar wrote:
>>
>> This patch introduces the use of function put_unaligned_le16.
>>
>> This is done using Coccinelle and semantic patch used is as follows:
>>
>> @a@
>> typedef u16, __le16;
>> {u16,__le16} e16;
>> identifier tmp;
>> expression ptr;
>> expression y,e;
>> type T;
>> @@
>>
>> - tmp = cpu_to_le16(y);
>>
>>    <+... when != tmp
>> (
>> - memcpy(ptr, (T)&tmp, \(2\|sizeof(u16)\|sizeof(__le16)\|sizeof(e16)\));
>> + put_unaligned_le16(y,ptr);
>> |
>> - memcpy(ptr, (T)&tmp, ...);
>> + put_unaligned_le16(y,ptr);
>> )
>>    ...+>
>> ? tmp = e
>>
>> @@ type T; identifier a.tmp; @@
>>
>> - T tmp;
>> ...when != tmp
>>
>> Signed-off-by: Vaishali Thakkar<vthakkar1994@...il.com>
>> ---
>>   drivers/nfc/port100.c | 6 ++----
>>   1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/nfc/port100.c b/drivers/nfc/port100.c
>> index 4ac4d31..f7cbca8 100644
>> --- a/drivers/nfc/port100.c
>> +++ b/drivers/nfc/port100.c
>> @@ -18,6 +18,7 @@
>>   #include<linux/module.h>
>>   #include<linux/usb.h>
>>   #include<net/nfc/digital.h>
>> +#include<linux/unaligned/access_ok.h>
>
>
> It is incorrect to use this header file as was pointed out by Johannes to me
> in a brcmfmac driver patch [1]. Unless this driver is architecture specific.
>
> Regards,
> Arend
>
> [1]
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=a1d69c60c44

Ok. Thanks for pointing out. I didn't know this. So, I guess using
<asm/unaligned.h> could make sense. Should I include this??

>>   #define VERSION "0.1"
>>
>> @@ -1136,7 +1137,6 @@ static int port100_in_send_cmd(struct
>> nfc_digital_dev *ddev,
>>   {
>>         struct port100 *dev = nfc_digital_get_drvdata(ddev);
>>         struct port100_cb_arg *cb_arg;
>> -       __le16 timeout;
>>
>>         cb_arg = kzalloc(sizeof(struct port100_cb_arg), GFP_KERNEL);
>>         if (!cb_arg)
>> @@ -1145,9 +1145,7 @@ static int port100_in_send_cmd(struct
>> nfc_digital_dev *ddev,
>>         cb_arg->complete_cb = cb;
>>         cb_arg->complete_arg = arg;
>>
>> -       timeout = cpu_to_le16(_timeout * 10);
>> -
>> -       memcpy(skb_push(skb, sizeof(__le16)),&timeout, sizeof(__le16));
>> +       put_unaligned_le16(_timeout * 10, skb_push(skb, sizeof(__le16)));
>>
>>         return port100_send_cmd_async(dev, PORT100_CMD_IN_COMM_RF, skb,
>>                                       port100_in_comm_rf_complete,
>> cb_arg);
>
>



-- 
Vaishali
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