Re: [Cocci] changing of_get_mac_address() to pass a buffer

[Michael Walle <michael@walle.cc>]

Hi Mansour,

Am 2021-04-04 19:48, schrieb Mansour Moufid:
> On Thu, Apr 1, 2021 at 4:13 AM Michael Walle <michael@walle.cc> wrote:
>> 
>> Hi,
>> 
>> so first I need to say I've never used coccinelle before,
>> so please bear with me ;)
>> 
>> To make of_get_mac_address() work with DSA ports (and a nvmem
>> provider) I'd need to change the semantics of of_get_mac_address().
>> Right now it returns a pointer to "const char *", I'd need to change
>> that so a buffer will be passed as a parameter in which the MAC
>> address gets stored.
>> 
>> (1) Usually the call is something like:
>> 
>>    const char *mac;
>>    mac = of_get_mac_address(np);
>>    if (!IS_ERR(mac))
>>      ether_addr_copy(ndev->dev_addr, mac);
>> 
>> This would need to be changed to:
>> 
>>    of_get_mac_address(np, ndev->dev_addr);
> 
> Here is one possible approach, doing the API change first then
> handling the conditionals. It seems to work.
> 
> @a@
> identifier x;
> expression y, z;
> @@
> -   x = of_get_mac_address(y);
> +   x = of_get_mac_address(y, z);
>     <...
> -   ether_addr_copy(z, x);
>     ...>
> 
> @@
> identifier a.x;
> @@
> -   if (<+... x ...+>) {}
> 
> @@
> identifier a.x;
> @@
>     if (<+... x ...+>) {
>         ...
>     }
> -   else {}
> 
> @@
> identifier a.x;
> expression e;
> @@
> -   if (<+... x ...+>@e)
> -       {}
> -   else
> +   if (!(e))
>         {...}
> 
> @@
> expression x, y, z;
> @@
> -   x = of_get_mac_address(y, z);
> +   of_get_mac_address(y, z);
>     ... when != x

Thanks a lot!

See also 
https://lore.kernel.org/netdev/20210405164643.21130-1-michael@walle.cc/

There were some "if (!(!IS_ERR(x))", which I needed to simplify
manually. Didn't noticed that in my previous script. I'm just
curious, is that also something coccinelle can simplify on its
own?

-michael
_______________________________________________
Cocci mailing list
Cocci@systeme.lip6.fr
https://systeme.lip6.fr/mailman/listinfo/cocci