[PATCH RFC ipsec-next 2/2] xfrm: Add a device independent napi instance

[Steffen Klassert]

This patch adds a napi instance for IPsec GRO.
With this, we handle IPsec GRO with no impact
on the generic networking code.

Signed-off-by: Steffen Klassert <steffen.klass...@secunet.com>
---
 net/xfrm/xfrm_input.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 86 insertions(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 6e3f025..c5fc12d 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -21,6 +21,90 @@
 static DEFINE_SPINLOCK(xfrm_input_afinfo_lock);
 static struct xfrm_input_afinfo __rcu *xfrm_input_afinfo[NPROTO];
 
+struct xfrm_napi {
+       struct sk_buff_head     napi_skbs;
+       struct napi_struct      napi;
+};
+
+static struct xfrm_napi __percpu *napis;
+
+static void xfrm_gro_receive(struct sk_buff *skb)
+{
+       struct xfrm_napi *xnapi;
+       struct net_device *dev = skb->dev;
+
+       if (!napis || skb_cloned(skb) || !(dev->features & NETIF_F_GRO)) {
+               netif_rx(skb);
+               return;
+       }
+
+       xnapi = this_cpu_ptr(napis);
+
+       if (skb_queue_len(&xnapi->napi_skbs) > netdev_max_backlog) {
+               atomic_long_inc(&dev->rx_dropped);
+               kfree_skb(skb);
+               return;
+       }
+
+       __skb_queue_tail(&xnapi->napi_skbs, skb);
+       if (skb_queue_len(&xnapi->napi_skbs) == 1)
+               napi_schedule(&xnapi->napi);
+}
+
+static int xfrm_gro_poll(struct napi_struct *napi, int budget)
+{
+       unsigned long flags;
+       struct sk_buff *skb;
+       int work_done = 0;
+       struct xfrm_napi *xnapi = container_of(napi, struct xfrm_napi, napi);
+
+       while (work_done < budget) {
+               skb = __skb_dequeue(&xnapi->napi_skbs);
+               if (!skb)
+                       break;
+               napi_gro_receive(napi, skb);
+               work_done++;
+       }
+
+       if (work_done < budget) {
+               napi_gro_flush(napi, false);
+
+               if (likely(list_empty(&napi->poll_list))) {
+                       WARN_ON_ONCE(!test_and_clear_bit(NAPI_STATE_SCHED, 
&napi->state));
+               } else {
+                       /* If n->poll_list is not empty, we need to mask irqs */
+                       local_irq_save(flags);
+                       __napi_complete(napi);
+                       local_irq_restore(flags);
+               }
+       }
+
+       return work_done;
+}
+
+static void xfrm_gro_init(void)
+{
+       int i;
+
+       /* Napi remains disabled if we can't alloc memory. */
+       napis = alloc_percpu(struct xfrm_napi);
+
+       for_each_possible_cpu(i) {
+               struct xfrm_napi *xnapi = per_cpu_ptr(napis, i);
+
+               __skb_queue_head_init(&xnapi->napi_skbs);
+
+               set_bit(NAPI_STATE_NO_BUSY_POLL, &xnapi->napi.state);
+
+               INIT_LIST_HEAD(&xnapi->napi.poll_list);
+               xnapi->napi.poll = xfrm_gro_poll;
+               xnapi->napi.weight = 64;
+               xnapi->napi.gro_list = NULL;
+               xnapi->napi.gro_count = 0;
+               xnapi->napi.skb = NULL;
+       }
+}
+
 int xfrm_input_register_afinfo(struct xfrm_input_afinfo *afinfo)
 {
        int err = 0;
@@ -371,7 +455,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 
spi, int encap_type)
 
        if (decaps) {
                skb_dst_drop(skb);
-               netif_rx(skb);
+               xfrm_gro_receive(skb);
                return 0;
        } else {
                return x->inner_mode->afinfo->transport_finish(skb, async);
@@ -394,6 +478,7 @@ int xfrm_input_resume(struct sk_buff *skb, int nexthdr)
 
 void __init xfrm_input_init(void)
 {
+       xfrm_gro_init();
        secpath_cachep = kmem_cache_create("secpath_cache",
                                           sizeof(struct sec_path),
                                           0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
-- 
1.9.1