Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933446Ab0FEO4V (ORCPT ); Sat, 5 Jun 2010 10:56:21 -0400 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 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=GggHTZfzAaTlRehWQx+TPFTxNoXB/ZXAGKJFJ9CLyEhFlMH+pjCf10QKlWqHspCmFk XO9Ra/XUlSYlhmYLK16IrLLZcFNn2MohNR8Sn6R7TP+5D2nPlJEUdkB9aKGpD4bHEPsK Lcp1rtkTzozOaraoKMtBmPsAbBosho1mElyxU= Subject: Re: [RFC PATCH v7 11/19] Use callback to deal with skb_release_data() specially. From: Eric Dumazet To: xiaohui.xin@intel.com 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.hengli.com.au, jdike@linux.intel.com In-Reply-To: <1275732899-5423-11-git-send-email-xiaohui.xin@intel.com> 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> Content-Type: text/plain; charset="UTF-8" Date: Sat, 05 Jun 2010 16:56:13 +0200 Message-ID: <1275749773.5238.244.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2765 Lines: 86 Le samedi 05 juin 2010 à 18:14 +0800, xiaohui.xin@intel.com a écrit : > From: Xin Xiaohui > > If buffer is external, then use the callback to destruct > buffers. > > 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(-) > > 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 *skb) > > static void skb_release_data(struct sk_buff *skb) > { > + /* check if the skb has external buffers, we have use destructor_arg > + * here to indicate > + */ > + struct skb_external_page *ext_page = 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); > > + /* 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 = 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; - 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]; }; /* We divide dataref into two halves. The higher 16 bits hold references -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/