Re: kfree_skb: unnecessary check ?

[kuznet@xxxxxxxxxxxxx]

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