Re: [Outreachy kernel] [PATCH v3 1/2] Staging: rtl8188eu: Use put_unaligned_le16

[Preeti U Murthy <preeti@linux.vnet.ibm.com>]

Hi Vaishali,

On 02/20/2015 09:00 AM, Vaishali Thakkar wrote:
> Using byte ordering functions and then memcpy() is risky and
> prone to hide errors which are hard to track down. So, this
> patch introduces the use of function put_unaligned_le16 which
> makes the code clear. Here, use of variable tim_bitmap_le
> and variable itself is removed. Also, to be compatible with the
> changes header file is added too.

You don't really need to explain the inclusion of header files since it
would be understood that it is to link the newly introduced functions in
the patch. But you don't need to send out a new version just for
correcting this. The patchset looks good to me.

Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
> 
> Coccinelle is used to do this change and semantic patch used for
> this is as follows:
> 
> @a@
> typedef __le16;
> __le16 e16;
> identifier tmp;
> expression ptr;
> expression y,e;
> type T;
> @@
> 
> - tmp = cpu_to_le16(y);
> 
> <+... when != tmp
> (
> - memcpy(ptr, (T)&tmp, \(2\|sizeof(__le16)\|sizeof(e16)\));
> + 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@gmail.com>
> ---
> Changes since v2:
> 	-Edit commit log
> 	-Merge this patch in a patch-series
> 
> Changes since v1:
> 	-Remove use of variable tim_bitmap_le
> 	-Remove variable tim_bitmap_le
> 	-Add header file to be compatible with the changes
> 	-Edit commit log
> 
>  drivers/staging/rtl8188eu/core/rtw_ap.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/staging/rtl8188eu/core/rtw_ap.c b/drivers/staging/rtl8188eu/core/rtw_ap.c
> index da19145..e65ee6e 100644
> --- a/drivers/staging/rtl8188eu/core/rtw_ap.c
> +++ b/drivers/staging/rtl8188eu/core/rtw_ap.c
> @@ -23,6 +23,7 @@
>  #include <drv_types.h>
>  #include <wifi.h>
>  #include <ieee80211.h>
> +#include <asm/unaligned.h>
> 
>  #ifdef CONFIG_88EU_AP_MODE
> 
> @@ -78,11 +79,8 @@ static void update_BCNTIM(struct adapter *padapter)
>  	if (true) {
>  		u8 *p, *dst_ie, *premainder_ie = NULL;
>  		u8 *pbackup_remainder_ie = NULL;
> -		__le16 tim_bitmap_le;
>  		uint offset, tmp_len, tim_ielen, tim_ie_offset, remainder_ielen;
> 
> -		tim_bitmap_le = cpu_to_le16(pstapriv->tim_bitmap);
> -
>  		p = rtw_get_ie(pie + _FIXED_IE_LENGTH_, _TIM_IE_, &tim_ielen, pnetwork_mlmeext->IELength - _FIXED_IE_LENGTH_);
>  		if (p != NULL && tim_ielen > 0) {
>  			tim_ielen += 2;
> @@ -137,9 +135,9 @@ static void update_BCNTIM(struct adapter *padapter)
>  			*dst_ie++ = 0;
> 
>  		if (tim_ielen == 4) {
> -			*dst_ie++ = *(u8 *)&tim_bitmap_le;
> +			*dst_ie++ = pstapriv->tim_bitmap & 0xff;
>  		} else if (tim_ielen == 5) {
> -			memcpy(dst_ie, &tim_bitmap_le, 2);
> +			put_unaligned_le16(pstapriv->tim_bitmap, dst_ie);
>  			dst_ie += 2;
>  		}
>