From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Duyck Subject: Re: [PATCH net-next v2 1/6] skbuff: Add skb_list_linearize() Date: Thu, 29 Jan 2015 19:28:50 -0800 Message-ID: <54CAFA72.60207@gmail.com> References: <1422574164-1860-1-git-send-email-pshelar@nicira.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Pravin B Shelar , davem@davemloft.net Return-path: Received: from mail-pa0-f51.google.com ([209.85.220.51]:45000 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752517AbbA3D2w (ORCPT ); Thu, 29 Jan 2015 22:28:52 -0500 Received: by mail-pa0-f51.google.com with SMTP id fb1so46923313pad.10 for ; Thu, 29 Jan 2015 19:28:51 -0800 (PST) In-Reply-To: <1422574164-1860-1-git-send-email-pshelar@nicira.com> Sender: netdev-owner@vger.kernel.org List-ID: On 01/29/2015 03:29 PM, Pravin B Shelar wrote: > similar to skb_linearize(), this API takes skb list as arg and > linearize it into one big skb. STT driver patch will use this. > > Signed-off-by: Pravin B Shelar > --- > Fixed according to comments from Eric. > --- > include/linux/skbuff.h | 2 ++ > net/core/skbuff.c | 34 ++++++++++++++++++++++++++++++++++ > 2 files changed, 36 insertions(+) > > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > index 85ab7d7..c9194c1 100644 > --- a/include/linux/skbuff.h > +++ b/include/linux/skbuff.h > @@ -2532,6 +2532,8 @@ static inline int skb_linearize(struct sk_buff *skb) > return skb_is_nonlinear(skb) ? __skb_linearize(skb) : 0; > } > > +int skb_list_linearize(struct sk_buff *head, gfp_t gfp_mask); > + > /** > * skb_has_shared_frag - can any frag be overwritten > * @skb: buffer to test > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 56db472..d6358a7 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -2329,6 +2329,40 @@ void skb_copy_and_csum_dev(const struct sk_buff *skb, u8 *to) > } > EXPORT_SYMBOL(skb_copy_and_csum_dev); > > +int skb_list_linearize(struct sk_buff *head, gfp_t gfp_mask) > +{ > + struct sk_buff *skb; > + int tlen = 0; > + int err; > + > + err = skb_linearize(head); > + if (err) > + return err; What is the point in linearizing the head if you are just going to reallocated it pskb_expand_head anyway? It seems like you should probably just be calling __pskb_pull_tail after your call pskb_expand_head below. > + skb = head->next; > + while (skb) { > + tlen += skb->len; > + skb = skb->next; > + } > + err = pskb_expand_head(head, 0, tlen, gfp_mask); > + if (err) > + return err; > + > + skb = head->next; > + while (skb) { > + err = skb_copy_bits(skb, 0, skb_tail_pointer(head), skb->len); > + if (err) > + return err; > + head->tail += skb->len; > + skb = skb->next; > + } > + kfree_skb_list(head->next); > + head->next = NULL; > + head->len += tlen; > + return 0; > +} > +EXPORT_SYMBOL(skb_list_linearize); > + > /** > * skb_dequeue - remove from the head of the queue > * @list: list to dequeue from I'm not completely convinced this is even necessary. Seems like you are wasting cycles copying the frames around when you could probably just pull the header of the first frame and then use page frages to fill in the rest. - Alex