Re: [PATCH] staging: r8188eu: simplify complex pointer casting

Greg Kroah-Hartman
2022-11-06T16:43:41Z

On Sun, Nov 06, 2022 at 01:56:01PM +0530, Deepak R Varma wrote:
> Pointers to structures udphdr and dhcpMessage are derived by casting
> adjacent pointers with size_t. Such typecast of pointer using size_t
> is not preferred. The code looks complex and delicate. Simplify such
> casting by utilizing generic "void *" casting.
> While at this change, remove the unnecessary __be32 casting for member
> variable "cookie".

Wait, why is that unecessary?

And why is that part of this change, that should be a separate one, so
that it can be reverted when it's found to be buggy :)

>
> Suggested-by: Joe Perches <joe@perches.com>
> Signed-off-by: Deepak R Varma <drv@mailo.com>
> ---
> drivers/staging/r8188eu/core/rtw_br_ext.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/staging/r8188eu/core/rtw_br_ext.c b/drivers/staging/r8188eu/core/rtw_br_ext.c
> index a23f7df373ed..e9b0906d0d74 100644
> --- a/drivers/staging/r8188eu/core/rtw_br_ext.c
> +++ b/drivers/staging/r8188eu/core/rtw_br_ext.c
> @@ -610,13 +610,15 @@ void dhcp_flag_bcast(struct adapter *priv, struct sk_buff *skb)
> struct iphdr *iph = (struct iphdr *)(skb->data + ETH_HLEN);
>
> if (iph->protocol == IPPROTO_UDP) { /* UDP */
> - struct udphdr *udph = (struct udphdr *)((size_t)iph + (iph->ihl << 2));
> + struct udphdr *udph = (void *)iph + (iph->ihl << 2);
>
> if ((udph->source == htons(CLIENT_PORT)) &&
> (udph->dest == htons(SERVER_PORT))) { /* DHCP request */
> - struct dhcpMessage *dhcph =
> - (struct dhcpMessage *)((size_t)udph + sizeof(struct udphdr));
> - u32 cookie = be32_to_cpu((__be32)dhcph->cookie);
> + u32 cookie;
> + struct dhcpMessage *dhcph;

Why reorder these variables?

> +
> + dhcph = (void *)udph + sizeof(struct udphdr);
> + cookie = be32_to_cpu(dhcph->cookie);

The cookie change should be separate please.

thanks,

greg k-h