From mboxrd@z Thu Jan 1 00:00:00 1970 From: xiaohui.xin@intel.com Subject: Re: [PATCH v15 00/17] Provide a zero-copy method on KVM virtio-net. Date: Wed, 10 Nov 2010 17:23:28 +0800 Message-ID: <1289381008-5484-1-git-send-email-xiaohui.xin@intel.com> References: <20101109.091516.112581012.davem@davemloft.net> Cc: Xin Xiaohui To: netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mst@redhat.com, mingo@elte.hu, herbert@gondor.apana.org.au, jdike@linux.intel.com, davem@davemloft.net Return-path: In-Reply-To: <20101109.091516.112581012.davem@davemloft.net> Sender: kvm-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Xin Xiaohui >2) The idea to key off of skb->dev in skb_release_data() is > fundamentally flawed since many actions can change skb->dev on you, > which will end up causing a leak of your external data areas. How about this one? If the destructor_arg is not a good candidate, then I have to add an apparent field in shinfo. Thanks Xiaohui diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 10ba67d..ad4636e 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -199,14 +199,15 @@ struct skb_shared_info { struct sk_buff *frag_list; struct skb_shared_hwtstamps hwtstamps; + /* Intermediate layers must ensure that destructor_arg + * remains valid until skb destructor */ + void * destructor_arg; + /* * Warning : all fields before dataref are cleared in __alloc_skb() */ atomic_t dataref; - /* Intermediate layers must ensure that destructor_arg - * remains valid until skb destructor */ - void * destructor_arg; /* must be last field, see pskb_expand_head() */ skb_frag_t frags[MAX_SKB_FRAGS]; }; diff --git a/net/core/skbuff.c b/net/core/skbuff.c index c83b421..eb040f4 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -343,6 +343,13 @@ static void skb_release_data(struct sk_buff *skb) if (skb_has_frags(skb)) skb_drop_fraglist(skb); + if (skb_shinfo(skb)->destructor_arg) { + struct skb_ext_page *ext_page = + skb_shinfo(skb)->destructor_arg; + if (ext_page->dtor) + ext_page->dtor(ext_page); + } + kfree(skb->head); } } -- 1.7.3