[PATCH ipsec-next 2/2] xfrm interface: store xfrmi contexts in a hash by if_id

[Eyal Birger]

xfrmi_lookup() is called on every packet. Using a single list for
looking up if_id becomes a bottleneck when having many xfrm interfaces.

Signed-off-by: Eyal Birger <eyal.bir...@gmail.com>
---
 net/xfrm/xfrm_interface.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/net/xfrm/xfrm_interface.c b/net/xfrm/xfrm_interface.c
index 069dafeba873..f4ec117e9110 100644
--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -49,20 +49,28 @@ static struct rtnl_link_ops xfrmi_link_ops __read_mostly;
 static unsigned int xfrmi_net_id __read_mostly;
 static const struct net_device_ops xfrmi_netdev_ops;
 
+#define XFRMI_HASH_BITS        8
+#define XFRMI_HASH_SIZE        BIT(XFRMI_HASH_BITS)
+
 struct xfrmi_net {
        /* lists for storing interfaces in use */
-       struct xfrm_if __rcu *xfrmi[1];
+       struct xfrm_if __rcu *xfrmi[XFRMI_HASH_SIZE];
 };
 
 #define for_each_xfrmi_rcu(start, xi) \
        for (xi = rcu_dereference(start); xi; xi = rcu_dereference(xi->next))
 
+static u32 xfrmi_hash(u32 if_id)
+{
+       return hash_32(if_id, XFRMI_HASH_BITS);
+}
+
 static struct xfrm_if *xfrmi_lookup(struct net *net, struct xfrm_state *x)
 {
        struct xfrmi_net *xfrmn = net_generic(net, xfrmi_net_id);
        struct xfrm_if *xi;
 
-       for_each_xfrmi_rcu(xfrmn->xfrmi[0], xi) {
+       for_each_xfrmi_rcu(xfrmn->xfrmi[xfrmi_hash(x->if_id)], xi) {
                if (x->if_id == xi->p.if_id &&
                    (xi->dev->flags & IFF_UP))
                        return xi;
@@ -107,7 +115,7 @@ static struct xfrm_if *xfrmi_decode_session(struct sk_buff 
*skb,
 
 static void xfrmi_link(struct xfrmi_net *xfrmn, struct xfrm_if *xi)
 {
-       struct xfrm_if __rcu **xip = &xfrmn->xfrmi[0];
+       struct xfrm_if __rcu **xip = &xfrmn->xfrmi[xfrmi_hash(xi->p.if_id)];
 
        rcu_assign_pointer(xi->next , rtnl_dereference(*xip));
        rcu_assign_pointer(*xip, xi);
@@ -118,7 +126,7 @@ static void xfrmi_unlink(struct xfrmi_net *xfrmn, struct 
xfrm_if *xi)
        struct xfrm_if __rcu **xip;
        struct xfrm_if *iter;
 
-       for (xip = &xfrmn->xfrmi[0];
+       for (xip = &xfrmn->xfrmi[xfrmi_hash(xi->p.if_id)];
             (iter = rtnl_dereference(*xip)) != NULL;
             xip = &iter->next) {
                if (xi == iter) {
@@ -162,7 +170,7 @@ static struct xfrm_if *xfrmi_locate(struct net *net, struct 
xfrm_if_parms *p)
        struct xfrm_if *xi;
        struct xfrmi_net *xfrmn = net_generic(net, xfrmi_net_id);
 
-       for (xip = &xfrmn->xfrmi[0];
+       for (xip = &xfrmn->xfrmi[xfrmi_hash(p->if_id)];
             (xi = rtnl_dereference(*xip)) != NULL;
             xip = &xi->next)
                if (xi->p.if_id == p->if_id)
@@ -761,11 +769,14 @@ static void __net_exit xfrmi_exit_batch_net(struct 
list_head *net_exit_list)
                struct xfrmi_net *xfrmn = net_generic(net, xfrmi_net_id);
                struct xfrm_if __rcu **xip;
                struct xfrm_if *xi;
+               int i;
 
-               for (xip = &xfrmn->xfrmi[0];
-                    (xi = rtnl_dereference(*xip)) != NULL;
-                    xip = &xi->next)
-                       unregister_netdevice_queue(xi->dev, &list);
+               for (i = 0; i < XFRMI_HASH_SIZE; i++) {
+                       for (xip = &xfrmn->xfrmi[i];
+                            (xi = rtnl_dereference(*xip)) != NULL;
+                            xip = &xi->next)
+                               unregister_netdevice_queue(xi->dev, &list);
+               }
        }
        unregister_netdevice_many(&list);
        rtnl_unlock();
-- 
2.25.1