[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH V3] xen/netfront: handle compound page fragments on transmit
On Wed, Nov 21, 2012 at 12:02:16PM +0000, Ian Campbell wrote: > An SKB paged fragment can consist of a compound page with order > 0. > However the netchannel protocol deals only in PAGE_SIZE frames. > > Handle this in xennet_make_frags by iterating over the frames which > make up the page. > > This is the netfront equivalent to 6a8ed462f16b for netback. > > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx> > Cc: netdev@xxxxxxxxxxxxxxx > Cc: xen-devel@xxxxxxxxxxxxx > Cc: Eric Dumazet <edumazet@xxxxxxxxxx> > Cc: Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> David, would you like me to send it to Linus via my tree or are you OK sending him a git pull with this patch (and hopefully some other ones?) Thank you. > Cc: ANNIE LI <annie.li@xxxxxxxxxx> > Cc: Sander Eikelenboom <linux@xxxxxxxxxxxxxx> > Cc: Stefan Bader <stefan.bader@xxxxxxxxxxxxx> > --- > v3: limit to 80-characters. Use net_alert_ratelimited. > v2: check we have enough room in the ring and that the other end can > cope with the number of slots in a single frame > --- > drivers/net/xen-netfront.c | 98 ++++++++++++++++++++++++++++++++++--------- > 1 files changed, 77 insertions(+), 21 deletions(-) > > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > index caa0110..fc24eb9 100644 > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c > @@ -452,29 +452,85 @@ static void xennet_make_frags(struct sk_buff *skb, > struct net_device *dev, > /* Grant backend access to each skb fragment page. */ > for (i = 0; i < frags; i++) { > skb_frag_t *frag = skb_shinfo(skb)->frags + i; > + struct page *page = skb_frag_page(frag); > > - tx->flags |= XEN_NETTXF_more_data; > + len = skb_frag_size(frag); > + offset = frag->page_offset; > > - id = get_id_from_freelist(&np->tx_skb_freelist, np->tx_skbs); > - np->tx_skbs[id].skb = skb_get(skb); > - tx = RING_GET_REQUEST(&np->tx, prod++); > - tx->id = id; > - ref = gnttab_claim_grant_reference(&np->gref_tx_head); > - BUG_ON((signed short)ref < 0); > + /* Data must not cross a page boundary. */ > + BUG_ON(len + offset > PAGE_SIZE<<compound_order(page)); > > - mfn = pfn_to_mfn(page_to_pfn(skb_frag_page(frag))); > - gnttab_grant_foreign_access_ref(ref, np->xbdev->otherend_id, > - mfn, GNTMAP_readonly); > + /* Skip unused frames from start of page */ > + page += offset >> PAGE_SHIFT; > + offset &= ~PAGE_MASK; > > - tx->gref = np->grant_tx_ref[id] = ref; > - tx->offset = frag->page_offset; > - tx->size = skb_frag_size(frag); > - tx->flags = 0; > + while (len > 0) { > + unsigned long bytes; > + > + BUG_ON(offset >= PAGE_SIZE); > + > + bytes = PAGE_SIZE - offset; > + if (bytes > len) > + bytes = len; > + > + tx->flags |= XEN_NETTXF_more_data; > + > + id = get_id_from_freelist(&np->tx_skb_freelist, > + np->tx_skbs); > + np->tx_skbs[id].skb = skb_get(skb); > + tx = RING_GET_REQUEST(&np->tx, prod++); > + tx->id = id; > + ref = gnttab_claim_grant_reference(&np->gref_tx_head); > + BUG_ON((signed short)ref < 0); > + > + mfn = pfn_to_mfn(page_to_pfn(page)); > + gnttab_grant_foreign_access_ref(ref, > + np->xbdev->otherend_id, > + mfn, GNTMAP_readonly); > + > + tx->gref = np->grant_tx_ref[id] = ref; > + tx->offset = offset; > + tx->size = bytes; > + tx->flags = 0; > + > + offset += bytes; > + len -= bytes; > + > + /* Next frame */ > + if (offset == PAGE_SIZE && len) { > + BUG_ON(!PageCompound(page)); > + page++; > + offset = 0; > + } > + } > } > > np->tx.req_prod_pvt = prod; > } > > +/* > + * Count how many ring slots are required to send the frags of this > + * skb. Each frag might be a compound page. > + */ > +static int xennet_count_skb_frag_slots(struct sk_buff *skb) > +{ > + int i, frags = skb_shinfo(skb)->nr_frags; > + int pages = 0; > + > + for (i = 0; i < frags; i++) { > + skb_frag_t *frag = skb_shinfo(skb)->frags + i; > + unsigned long size = skb_frag_size(frag); > + unsigned long offset = frag->page_offset; > + > + /* Skip unused frames from start of page */ > + offset &= ~PAGE_MASK; > + > + pages += PFN_UP(offset + size); > + } > + > + return pages; > +} > + > static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev) > { > unsigned short id; > @@ -487,23 +543,23 @@ static int xennet_start_xmit(struct sk_buff *skb, > struct net_device *dev) > grant_ref_t ref; > unsigned long mfn; > int notify; > - int frags = skb_shinfo(skb)->nr_frags; > + int slots; > unsigned int offset = offset_in_page(data); > unsigned int len = skb_headlen(skb); > unsigned long flags; > > - frags += DIV_ROUND_UP(offset + len, PAGE_SIZE); > - if (unlikely(frags > MAX_SKB_FRAGS + 1)) { > - printk(KERN_ALERT "xennet: skb rides the rocket: %d frags\n", > - frags); > - dump_stack(); > + slots = DIV_ROUND_UP(offset + len, PAGE_SIZE) + > + xennet_count_skb_frag_slots(skb); > + if (unlikely(slots > MAX_SKB_FRAGS + 1)) { > + net_alert_ratelimited( > + "xennet: skb rides the rocket: %d slots\n", slots); > goto drop; > } > > spin_lock_irqsave(&np->tx_lock, flags); > > if (unlikely(!netif_carrier_ok(dev) || > - (frags > 1 && !xennet_can_sg(dev)) || > + (slots > 1 && !xennet_can_sg(dev)) || > netif_needs_gso(skb, netif_skb_features(skb)))) { > spin_unlock_irqrestore(&np->tx_lock, flags); > goto drop; > -- > 1.7.2.5 > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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