Re: [PATCH v14 06/17] Use callback to deal with skb_release_data() specially.

Eric Dumazet
2010-11-04T09:04:30Z

Le jeudi 04 novembre 2010 à 17:05 +0800, xiaohui.xin@intel.com a écrit :
> From: Xin Xiaohui <xiaohui.xin@intel.com>
>
> If buffer is external, then use the callback to destruct
> buffers.
>
> Signed-off-by: Xin Xiaohui <xiaohui.xin@intel.com>
> Signed-off-by: Zhao Yu <yzhao81new@gmail.com>
> Reviewed-by: Jeff Dike <jdike@linux.intel.com>
> ---
> net/core/skbuff.c | 8 ++++++++
> 1 files changed, 8 insertions(+), 0 deletions(-)
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index c83b421..5e6d69c 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -210,6 +210,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
>
> /* make sure we initialize shinfo sequentially */
> shinfo = skb_shinfo(skb);
> + shinfo->destructor_arg = NULL;

Hmm, I suggest you read the comment two lines above.

If destructor_arg is now cleared each time we allocate a new skb, then,
please move it before dataref in shinfo structure, so that the following
memset() does the job efficiently...

> memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
> atomic_set(&shinfo->dataref, 1);
>
> @@ -343,6 +344,13 @@ static void skb_release_data(struct sk_buff *skb)
> if (skb_has_frags(skb))
> skb_drop_fraglist(skb);
>
> + if (skb->dev && dev_is_mpassthru(skb->dev)) {
> + struct skb_ext_page *ext_page =
> + skb_shinfo(skb)->destructor_arg;
> + if (ext_page && ext_page->dtor)
> + ext_page->dtor(ext_page);
> + }
> +
> kfree(skb->head);
> }
> }