Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932975Ab2HWO2Q (ORCPT ); Thu, 23 Aug 2012 10:28:16 -0400 Received: from rcsinet15.oracle.com ([148.87.113.117]:42029 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751444Ab2HWO2O (ORCPT ); Thu, 23 Aug 2012 10:28:14 -0400 Date: Thu, 23 Aug 2012 10:17:40 -0400 From: Konrad Rzeszutek Wilk To: Ian Campbell Cc: David Miller , "mgorman@suse.de" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , "xen-devel@lists.xensource.com" , "konrad@darnok.org" , "akpm@linux-foundation.org" Subject: Re: [PATCH] netvm: check for page == NULL when propogating the skb->pfmemalloc flag Message-ID: <20120823141740.GA30305@phenom.dumpdata.com> References: <20120807085554.GF29814@suse.de> <20120808.155046.820543563969484712.davem@davemloft.net> <1345631207.6821.140.camel@zakaz.uk.xensource.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1345631207.6821.140.camel@zakaz.uk.xensource.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: ucsinet22.oracle.com [156.151.31.94] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4893 Lines: 140 On Wed, Aug 22, 2012 at 11:26:47AM +0100, Ian Campbell wrote: > On Wed, 2012-08-08 at 23:50 +0100, David Miller wrote: > > Just use something like a call to __pskb_pull_tail(skb, len) and all > > that other crap around that area can simply be deleted. > > I think you mean something like this, which works for me, although I've > only lightly tested it. > I've tested it heavily and works great. Tested-by: Konrad Rzeszutek Wilk and I took a look at it too and: Acked-by: Konrad Rzeszutek Wilk > Ian. > > 8<---------------------------------------- > > >From 9e47e3e87a33b45974448649a97859a479183041 Mon Sep 17 00:00:00 2001 > From: Ian Campbell > Date: Wed, 22 Aug 2012 10:15:29 +0100 > Subject: [PATCH] xen-netfront: use __pskb_pull_tail to ensure linear area is big enough on RX > > I'm slightly concerned by the "only in exceptional circumstances" > comment on __pskb_pull_tail but the structure of an skb just created > by netfront shouldn't hit any of the especially slow cases. > > This approach still does slightly more work than the old way, since if > we pull up the entire first frag we now have to shuffle everything > down where before we just received into the right place in the first > place. > > Signed-off-by: Ian Campbell > Cc: Konrad Rzeszutek Wilk > Cc: Jeremy Fitzhardinge > Cc: Mel Gorman > Cc: xen-devel@lists.xensource.com > Cc: netdev@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > --- > drivers/net/xen-netfront.c | 39 ++++++++++----------------------------- > 1 files changed, 10 insertions(+), 29 deletions(-) > > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > index 3089990..650f79a 100644 > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c > @@ -57,8 +57,7 @@ > static const struct ethtool_ops xennet_ethtool_ops; > > struct netfront_cb { > - struct page *page; > - unsigned offset; > + int pull_to; > }; > > #define NETFRONT_SKB_CB(skb) ((struct netfront_cb *)((skb)->cb)) > @@ -867,15 +866,9 @@ static int handle_incoming_queue(struct net_device *dev, > struct sk_buff *skb; > > while ((skb = __skb_dequeue(rxq)) != NULL) { > - struct page *page = NETFRONT_SKB_CB(skb)->page; > - void *vaddr = page_address(page); > - unsigned offset = NETFRONT_SKB_CB(skb)->offset; > - > - memcpy(skb->data, vaddr + offset, > - skb_headlen(skb)); > + int pull_to = NETFRONT_SKB_CB(skb)->pull_to; > > - if (page != skb_frag_page(&skb_shinfo(skb)->frags[0])) > - __free_page(page); > + __pskb_pull_tail(skb, pull_to - skb_headlen(skb)); > > /* Ethernet work: Delayed to here as it peeks the header. */ > skb->protocol = eth_type_trans(skb, dev); > @@ -913,7 +906,6 @@ static int xennet_poll(struct napi_struct *napi, int budget) > struct sk_buff_head errq; > struct sk_buff_head tmpq; > unsigned long flags; > - unsigned int len; > int err; > > spin_lock(&np->rx_lock); > @@ -955,24 +947,13 @@ err: > } > } > > - NETFRONT_SKB_CB(skb)->page = > - skb_frag_page(&skb_shinfo(skb)->frags[0]); > - NETFRONT_SKB_CB(skb)->offset = rx->offset; > - > - len = rx->status; > - if (len > RX_COPY_THRESHOLD) > - len = RX_COPY_THRESHOLD; > - skb_put(skb, len); > + NETFRONT_SKB_CB(skb)->pull_to = rx->status; > + if (NETFRONT_SKB_CB(skb)->pull_to > RX_COPY_THRESHOLD) > + NETFRONT_SKB_CB(skb)->pull_to = RX_COPY_THRESHOLD; > > - if (rx->status > len) { > - skb_shinfo(skb)->frags[0].page_offset = > - rx->offset + len; > - skb_frag_size_set(&skb_shinfo(skb)->frags[0], rx->status - len); > - skb->data_len = rx->status - len; > - } else { > - __skb_fill_page_desc(skb, 0, NULL, 0, 0); > - skb_shinfo(skb)->nr_frags = 0; > - } > + skb_shinfo(skb)->frags[0].page_offset = rx->offset; > + skb_frag_size_set(&skb_shinfo(skb)->frags[0], rx->status); > + skb->data_len = rx->status; > > i = xennet_fill_frags(np, skb, &tmpq); > > @@ -999,7 +980,7 @@ err: > * receive throughout using the standard receive > * buffer size was cut by 25%(!!!). > */ > - skb->truesize += skb->data_len - (RX_COPY_THRESHOLD - len); > + skb->truesize += skb->data_len - RX_COPY_THRESHOLD; > skb->len += skb->data_len; > > if (rx->flags & XEN_NETRXF_csum_blank) > -- > 1.7.2.5 > > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org > -- 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/