From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH net-next V2 1/2] net: introduce skb_coalesce_rx_frag() Date: Fri, 01 Nov 2013 13:25:59 +0800 Message-ID: <52733B67.4030102@redhat.com> References: <1383220027-12278-1-git-send-email-jasowang@redhat.com> <1383229563.4857.71.camel@edumazet-glaptop.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: mwdalton@google.com, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kmindg@gmail.com, edumazet@google.com, davem@davemloft.net To: Eric Dumazet Return-path: In-Reply-To: <1383229563.4857.71.camel@edumazet-glaptop.roam.corp.google.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On 10/31/2013 10:26 PM, Eric Dumazet wrote: > On Thu, 2013-10-31 at 19:47 +0800, Jason Wang wrote: >> Sometimes we need to coalesce the rx frags to avoid frag list. One example is >> virtio-net driver which tries to use small frags for both MTU sized packet and >> GSO packet. So this patch introduce skb_coalesce_rx_frag() to do this. >> >> Cc: Rusty Russell >> Cc: Michael S. Tsirkin >> Cc: Michael Dalton >> Cc: Eric Dumazet >> Acked-by: Michael S. Tsirkin >> Signed-off-by: Jason Wang >> --- >> Changes from V1: >> - remove the useless off parameter. >> --- >> include/linux/skbuff.h | 3 +++ >> net/core/skbuff.c | 13 +++++++++++++ >> 2 files changed, 16 insertions(+) >> >> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h >> index 2c15497..fffaeaf 100644 >> --- a/include/linux/skbuff.h >> +++ b/include/linux/skbuff.h >> @@ -1372,6 +1372,9 @@ static inline void skb_fill_page_desc(struct sk_buff *skb, int i, >> void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off, >> int size, unsigned int truesize); >> >> +void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size, >> + unsigned int truesize); >> + >> #define SKB_PAGE_ASSERT(skb) BUG_ON(skb_shinfo(skb)->nr_frags) >> #define SKB_FRAG_ASSERT(skb) BUG_ON(skb_has_frag_list(skb)) >> #define SKB_LINEAR_ASSERT(skb) BUG_ON(skb_is_nonlinear(skb)) >> diff --git a/net/core/skbuff.c b/net/core/skbuff.c >> index 0ab32fa..87670e1 100644 >> --- a/net/core/skbuff.c >> +++ b/net/core/skbuff.c >> @@ -476,6 +476,19 @@ void skb_add_rx_frag(struct sk_buff *skb, int i, struct page *page, int off, >> } >> EXPORT_SYMBOL(skb_add_rx_frag); >> >> +void skb_coalesce_rx_frag(struct sk_buff *skb, int i, int size, >> + unsigned int truesize) >> +{ >> + skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; >> + >> + skb_frag_size_add(frag, size); >> + skb->len += size; >> + skb->data_len += size; >> + skb->truesize += truesize; > >> + skb_frag_unref(skb, i); > This unref is not logical, or should at least be > > __skb_frag_unref(frag); > > But I do think this is best done in the caller. > > In virtio_net this would be a : > > put_page(page); > > In tcp stack we do almost the same, but we take the reference on the > page if we could not coalesce with prio frag, instead of doing a get and > put in the other case. > > if (can_coalesce) { > skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); > } else { > get_page(page); > skb_fill_page_desc(skb, i, page, offset, copy); > } > Ok, get it. Will do a put_page() in V3. Thanks >> +} >> +EXPORT_SYMBOL(skb_coalesce_rx_frag); >> + >> static void skb_drop_list(struct sk_buff **listp) >> { >> kfree_skb_list(*listp); > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html