Re: kfree_skb: unnecessary check ?

[Patrick McHardy <kaber@xxxxxxxxx>]

kuznet@xxxxxxxxxxxxx wrote:

> Hello!
>
> > Is atomic_dec_and_test really necessary ? atomic_dec_and_test only 
> > returns true if its argument has hit zero, so it was 1 before.
> > If atomic_dec is only a bit cheaper than atomic_dec_and_test (which i 
> > guess it is), wouldn't it make more sense to use something like this:
> Does the prefix "atomic" not scare you? :-)
>
>
> > static inline void kfree_skb(struct sk_buff *skb)
> > {
> >    if (atomic_read(&skb->users) == 1)
> >        __kfree(skb);
> >    else
> >        atomic_dec(&skb->users);
> > }
>      else if (atomic_dec_and_test(&skb->users))
>            __kfree_skb(skb);
>
> If you still do not understand think why it does not look like:
>
> static inline void kfree_skb(struct sk_buff *skb)
> {
>    int users = skb->users;
>    if (users == 1)
>        __kfree(skb);
>    else
>        skb->users = users - 1;
> }
>
> Alexey
Hehe got it :)
Thanks
Patrick