From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [RFC PATCH v7 11/19] Use callback to deal with skb_release_data() specially. Date: Sat, 05 Jun 2010 16:56:13 +0200 Message-ID: <1275749773.5238.244.camel@edumazet-laptop> References: <1275732899-5423-1-git-send-email-xiaohui.xin@intel.com> <1275732899-5423-2-git-send-email-xiaohui.xin@intel.com> <1275732899-5423-3-git-send-email-xiaohui.xin@intel.com> <1275732899-5423-4-git-send-email-xiaohui.xin@intel.com> <1275732899-5423-5-git-send-email-xiaohui.xin@intel.com> <1275732899-5423-6-git-send-email-xiaohui.xin@intel.com> <1275732899-5423-7-git-send-email-xiaohui.xin@intel.com> <1275732899-5423-8-git-send-email-xiaohui.xin@intel.com> <1275732899-5423-9-git-send-email-xiaohui.xin@intel.com> <1275732899-5423-10-git-send-email-xiaohui.xin@intel.com> <1275732899-5423-11-git-send-email-xiaohui.xin@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mst@redhat.com, mingo@elte.hu, davem@davemloft.net, herbert@gondor.apana.org.au, jdike@linux.intel.com To: xiaohui.xin@intel.com Return-path: Received: from mail-ww0-f46.google.com ([74.125.82.46]:33185 "EHLO mail-ww0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933305Ab0FEO4T (ORCPT ); Sat, 5 Jun 2010 10:56:19 -0400 In-Reply-To: <1275732899-5423-11-git-send-email-xiaohui.xin@intel.com> Sender: netdev-owner@vger.kernel.org List-ID: Le samedi 05 juin 2010 =C3=A0 18:14 +0800, xiaohui.xin@intel.com a =C3=A9= crit : > From: Xin Xiaohui >=20 > If buffer is external, then use the callback to destruct > buffers. >=20 > Signed-off-by: Xin Xiaohui > Signed-off-by: Zhao Yu > Reviewed-by: Jeff Dike > --- > net/core/skbuff.c | 11 +++++++++++ > 1 files changed, 11 insertions(+), 0 deletions(-) >=20 > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 37587f0..418457c 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -385,6 +385,11 @@ static void skb_clone_fraglist(struct sk_buff *s= kb) > =20 > static void skb_release_data(struct sk_buff *skb) > { > + /* check if the skb has external buffers, we have use destructor_ar= g > + * here to indicate > + */ > + struct skb_external_page *ext_page =3D skb_shinfo(skb)->destructor_= arg; > + Oh well. This is v7 of your series, and nobody complained yet ? This is a new cache miss on a _critical_ path. > if (!skb->cloned || > !atomic_sub_return(skb->nohdr ? (1 << SKB_DATAREF_SHIFT) + 1 : = 1, > &skb_shinfo(skb)->dataref)) { > @@ -397,6 +402,12 @@ static void skb_release_data(struct sk_buff *skb= ) > if (skb_has_frags(skb)) > skb_drop_fraglist(skb); > =20 > + /* if the skb has external buffers, use destructor here, > + * since after that skb->head will be kfree, in case skb->head > + * from external buffer cannot use kfree to destroy. > + */ Why not deferring here the access to skb_shinfo(skb)->destructor_arg ? > + if (dev_is_mpassthru(skb->dev) && ext_page && ext_page->dtor) > + ext_page->dtor(ext_page); > kfree(skb->head); > } > } if (dev_is_mpassthru(skb->dev)) { struct skb_external_page *ext_page =3D skb_shinfo(skb)->destructor_arg; if (ext_page && ext_page->dtor) ext_page->dtor(ext_page); } destructor_arg should me moved before frags[] if you really want to use= it. diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index bf243fc..b136d90 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -202,10 +202,11 @@ struct skb_shared_info { */ atomic_t dataref; =20 - skb_frag_t frags[MAX_SKB_FRAGS]; /* Intermediate layers must ensure that destructor_arg * remains valid until skb destructor */ void * destructor_arg; + + skb_frag_t frags[MAX_SKB_FRAGS]; }; =20 /* We divide dataref into two halves. The higher 16 bits hold referen= ces