Re: [PATCH] netlink: Make groups check less stupid in netlink_bind()

[David Miller]

From: Dmitry Safonov <dima@xxxxxxxxxx>
Date: Mon,  3 Sep 2018 22:40:51 +0100

> As Linus noted, the test for 0 is needless, groups type can follow the
> usual kernel style and 8*sizeof(unsigned long) is BITS_PER_LONG:
> 
>> The code [..] isn't technically incorrect...
>> But it is stupid.
>> Why stupid? Because the test for 0 is pointless.
>>
>> Just doing
>>        if (nlk->ngroups < 8*sizeof(groups))
>>                groups &= (1UL << nlk->ngroups) - 1;
>>
>> would have been fine and more understandable, since the "mask by shift
>> count" already does the right thing for a ngroups value of 0. Now that
>> test for zero makes me go "what's special about zero?". It turns out
>> that the answer to that is "nothing".
> [..]
>> The type of "groups" is kind of silly too.
>>
>> Yeah, "long unsigned int" isn't _technically_ wrong. But we normally
>> call that type "unsigned long".
> 
> Cleanup my piece of pointlessness.
> 
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx
> Fairly-blamed-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>

Applied to net-next, thanks.