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authorEric Dumazet <edumazet@google.com>2012-09-27 19:29:05 +0000
committerDavid S. Miller <davem@davemloft.net>2012-10-01 17:01:46 -0400
commitc9e6bc644e557338221e75c242ab12c275a67d1b (patch)
treedea44a1edd85dccafc2d0973280d3a608d69eb02 /include/net/gro_cells.h
parent861b650101eb0c627d171eb18de81dddb93d395e (diff)
downloadlinux-c9e6bc644e557338221e75c242ab12c275a67d1b.tar.gz
net: add gro_cells infrastructure
This adds a new include file (include/net/gro_cells.h), to bring GRO (Generic Receive Offload) capability to tunnels, in a modular way. Because tunnels receive path is lockless, and GRO adds a serialization using a napi_struct, I chose to add an array of up to DEFAULT_MAX_NUM_RSS_QUEUES cells, so that multi queue devices wont be slowed down because of GRO layer. skb_get_rx_queue() is used as selector. In the future, we might add optional fanout capabilities, using rxhash for example. With help from Ben Hutchings who reminded me netif_get_num_default_rss_queues() function. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/gro_cells.h')
-rw-r--r--include/net/gro_cells.h103
1 files changed, 103 insertions, 0 deletions
diff --git a/include/net/gro_cells.h b/include/net/gro_cells.h
new file mode 100644
index 00000000000..4fd8a4b4b7e
--- /dev/null
+++ b/include/net/gro_cells.h
@@ -0,0 +1,103 @@
+#ifndef _NET_GRO_CELLS_H
+#define _NET_GRO_CELLS_H
+
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/netdevice.h>
+
+struct gro_cell {
+ struct sk_buff_head napi_skbs;
+ struct napi_struct napi;
+} ____cacheline_aligned_in_smp;
+
+struct gro_cells {
+ unsigned int gro_cells_mask;
+ struct gro_cell *cells;
+};
+
+static inline void gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
+{
+ unsigned long flags;
+ struct gro_cell *cell = gcells->cells;
+ struct net_device *dev = skb->dev;
+
+ if (!cell || skb_cloned(skb) || !(dev->features & NETIF_F_GRO)) {
+ netif_rx(skb);
+ return;
+ }
+
+ if (skb_rx_queue_recorded(skb))
+ cell += skb_get_rx_queue(skb) & gcells->gro_cells_mask;
+
+ if (skb_queue_len(&cell->napi_skbs) > netdev_max_backlog) {
+ atomic_long_inc(&dev->rx_dropped);
+ kfree_skb(skb);
+ return;
+ }
+
+ spin_lock_irqsave(&cell->napi_skbs.lock, flags);
+
+ __skb_queue_tail(&cell->napi_skbs, skb);
+ if (skb_queue_len(&cell->napi_skbs) == 1)
+ napi_schedule(&cell->napi);
+
+ spin_unlock_irqrestore(&cell->napi_skbs.lock, flags);
+}
+
+static inline int gro_cell_poll(struct napi_struct *napi, int budget)
+{
+ struct gro_cell *cell = container_of(napi, struct gro_cell, napi);
+ struct sk_buff *skb;
+ int work_done = 0;
+
+ while (work_done < budget) {
+ skb = skb_dequeue(&cell->napi_skbs);
+ if (!skb)
+ break;
+
+ napi_gro_receive(napi, skb);
+ work_done++;
+ }
+
+ if (work_done < budget)
+ napi_complete(napi);
+ return work_done;
+}
+
+static inline int gro_cells_init(struct gro_cells *gcells, struct net_device *dev)
+{
+ int i;
+
+ gcells->gro_cells_mask = roundup_pow_of_two(netif_get_num_default_rss_queues()) - 1;
+ gcells->cells = kcalloc(sizeof(struct gro_cell),
+ gcells->gro_cells_mask + 1,
+ GFP_KERNEL);
+ if (!gcells->cells)
+ return -ENOMEM;
+
+ for (i = 0; i <= gcells->gro_cells_mask; i++) {
+ struct gro_cell *cell = gcells->cells + i;
+
+ skb_queue_head_init(&cell->napi_skbs);
+ netif_napi_add(dev, &cell->napi, gro_cell_poll, 64);
+ napi_enable(&cell->napi);
+ }
+ return 0;
+}
+
+static inline void gro_cells_destroy(struct gro_cells *gcells)
+{
+ struct gro_cell *cell = gcells->cells;
+ int i;
+
+ if (!cell)
+ return;
+ for (i = 0; i <= gcells->gro_cells_mask; i++,cell++) {
+ netif_napi_del(&cell->napi);
+ skb_queue_purge(&cell->napi_skbs);
+ }
+ kfree(gcells->cells);
+ gcells->cells = NULL;
+}
+
+#endif