[Devel] Re: [PATCH 6/8] Make the sk_clone() lighter

[Pavel Emelyanov]

David Miller wrote:
> From: Pavel Emelyanov <xemul at openvz.org>
> Date: Wed, 31 Oct 2007 16:54:34 +0300
> 
>> The sk_prot_alloc() already performs all the stuff needed by the
>> sk_clone(). Besides, the sk_prot_alloc() requires almost twice
>> less arguments than the sk_alloc() does, so call the sk_prot_alloc()
>> saving the stack a bit.
>>
>> Signed-off-by: Pavel Emelyanov <xemul at openvz.org>
>>
>> ---
>>
>> diff --git a/net/core/sock.c b/net/core/sock.c
>> index e7537e4..c032f48 100644
>> --- a/net/core/sock.c
>> +++ b/net/core/sock.c
>> @@ -976,8 +976,9 @@ void sk_free(struct sock *sk)
>>  
>>  struct sock *sk_clone(const struct sock *sk, const gfp_t priority)
>>  {
>> -	struct sock *newsk = sk_alloc(sk->sk_net, sk->sk_family, priority, sk->sk_prot, 0);
>> -
>> +	struct sock *newsk;
>> +
>> +	newsk = sk_prot_alloc(sk->sk_prot, priority, sk->sk_family);
>>  	if (newsk != NULL) {
>>  		struct sk_filter *filter;
>>  
> 
> After we make this change, what will set up newsk->sk_net?

This will be done automatically in the sock_copy().

> That's part of what sk_alloc() was doing for us, and that's
> why we need to pass the extra argument.
> 

No it wasn't doing it for us, because the sk_net assignment was
done inside the if (zero_it) branch, but zero_it is 0 in this case.

Thanks,
Pavel