Date: Wed, 20 Feb 2008 14:57:32 +0100
From: Eric Dumazet <dada1@cosmosbay.com>
To: =?ISO-8859-1?B?IklscG8gSuRydmluZW4i?= <ilpo.jarvinen@helsinki.fi>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
       David Miller <davem@davemloft.net>,
       Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [RFC PATCH 1/8] [NET]: uninline skb_put, de-bloats a lot
Message-Id: <20080220145732.d716355e.dada1@cosmosbay.com>
In-Reply-To: <1203515238-22848-2-git-send-email-ilpo.jarvinen@helsinki.fi>
References: <1203515238-22848-1-git-send-email-ilpo.jarvinen@helsinki.fi>
	<1203515238-22848-2-git-send-email-ilpo.jarvinen@helsinki.fi>
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On Wed, 20 Feb 2008 15:47:11 +0200
"Ilpo J?rvinen" <ilpo.jarvinen@helsinki.fi> wrote:

> ~500 files changed
> ...
> kernel/uninlined.c:
>   skb_put                       | +104
>  1 function changed, 104 bytes added, diff: +104
> 
> vmlinux.o:
>  869 functions changed, 198 bytes added, 111003 bytes removed, diff: -110805
> 
> This change is INCOMPLETE, I think that the call to current_text_addr()
> should be rethought but I don't have a clue how to do that.

You want to use __builtin_return_address(0)

> 
> Signed-off-by: Ilpo J?rvinen <ilpo.jarvinen@helsinki.fi>
> ---
>  include/linux/skbuff.h |   20 +-------------------
>  net/core/skbuff.c      |   21 +++++++++++++++++++++
>  2 files changed, 22 insertions(+), 19 deletions(-)
> 
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 412672a..5925435 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -896,25 +896,7 @@ static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
>  	return tmp;
>  }
>  
> -/**
> - *	skb_put - add data to a buffer
> - *	@skb: buffer to use
> - *	@len: amount of data to add
> - *
> - *	This function extends the used data area of the buffer. If this would
> - *	exceed the total buffer size the kernel will panic. A pointer to the
> - *	first byte of the extra data is returned.
> - */
> -static inline unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
> -{
> -	unsigned char *tmp = skb_tail_pointer(skb);
> -	SKB_LINEAR_ASSERT(skb);
> -	skb->tail += len;
> -	skb->len  += len;
> -	if (unlikely(skb->tail > skb->end))
> -		skb_over_panic(skb, len, current_text_addr());
> -	return tmp;
> -}
> +extern unsigned char *skb_put(struct sk_buff *skb, unsigned int len);
>  
>  static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
>  {
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 4e35422..661d439 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -857,6 +857,27 @@ free_skb:
>  	return err;
>  }
>  
> +/**
> + *	skb_put - add data to a buffer
> + *	@skb: buffer to use
> + *	@len: amount of data to add
> + *
> + *	This function extends the used data area of the buffer. If this would
> + *	exceed the total buffer size the kernel will panic. A pointer to the
> + *	first byte of the extra data is returned.
> + */
> +unsigned char *skb_put(struct sk_buff *skb, unsigned int len)
> +{
> +	unsigned char *tmp = skb_tail_pointer(skb);
> +	SKB_LINEAR_ASSERT(skb);
> +	skb->tail += len;
> +	skb->len  += len;
> +	if (unlikely(skb->tail > skb->end))
> +		skb_over_panic(skb, len, current_text_addr());
> +	return tmp;
> +}
> +EXPORT_SYMBOL(skb_put);
> +
>  /* Trims skb to length len. It can change skb pointers.
>   */
>  
> -- 
> 1.5.2.2
> 
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