fib: RCU conversion of fib_lookup()
fib_lookup() converted to be called in RCU protected context, no
reference taken and released on a contended cache line (fib_clntref)
fib_table_lookup() and fib_semantic_match() get an additional parameter.
struct fib_info gets an rcu_head field, and is freed after an rcu grace
period.
Stress test :
(Sending 160.000.000 UDP frames on same neighbour,
IP route cache disabled, dual E5540 @2.53GHz,
32bit kernel, FIB_HASH) (about same results for FIB_TRIE)
Before patch :
real 1m31.199s
user 0m13.761s
sys 23m24.780s
After patch:
real 1m5.375s
user 0m14.997s
sys 15m50.115s
Before patch Profile :
13044.00 15.4% __ip_route_output_key vmlinux
8438.00 10.0% dst_destroy vmlinux
5983.00 7.1% fib_semantic_match vmlinux
5410.00 6.4% fib_rules_lookup vmlinux
4803.00 5.7% neigh_lookup vmlinux
4420.00 5.2% _raw_spin_lock vmlinux
3883.00 4.6% rt_set_nexthop vmlinux
3261.00 3.9% _raw_read_lock vmlinux
2794.00 3.3% fib_table_lookup vmlinux
2374.00 2.8% neigh_resolve_output vmlinux
2153.00 2.5% dst_alloc vmlinux
1502.00 1.8% _raw_read_lock_bh vmlinux
1484.00 1.8% kmem_cache_alloc vmlinux
1407.00 1.7% eth_header vmlinux
1406.00 1.7% ipv4_dst_destroy vmlinux
1298.00 1.5% __copy_from_user_ll vmlinux
1174.00 1.4% dev_queue_xmit vmlinux
1000.00 1.2% ip_output vmlinux
After patch Profile :
13712.00 15.8% dst_destroy vmlinux
8548.00 9.9% __ip_route_output_key vmlinux
7017.00 8.1% neigh_lookup vmlinux
4554.00 5.3% fib_semantic_match vmlinux
4067.00 4.7% _raw_read_lock vmlinux
3491.00 4.0% dst_alloc vmlinux
3186.00 3.7% neigh_resolve_output vmlinux
3103.00 3.6% fib_table_lookup vmlinux
2098.00 2.4% _raw_read_lock_bh vmlinux
2081.00 2.4% kmem_cache_alloc vmlinux
2013.00 2.3% _raw_spin_lock vmlinux
1763.00 2.0% __copy_from_user_ll vmlinux
1763.00 2.0% ip_output vmlinux
1761.00 2.0% ipv4_dst_destroy vmlinux
1631.00 1.9% eth_header vmlinux
1440.00 1.7% _raw_read_unlock_bh vmlinux
Reference results, if IP route cache is enabled :
real 0m29.718s
user 0m10.845s
sys 7m37.341s
25213.00 29.5% __ip_route_output_key vmlinux
9011.00 10.5% dst_release vmlinux
4817.00 5.6% ip_push_pending_frames vmlinux
4232.00 5.0% ip_finish_output vmlinux
3940.00 4.6% udp_sendmsg vmlinux
3730.00 4.4% __copy_from_user_ll vmlinux
3716.00 4.4% ip_route_output_flow vmlinux
2451.00 2.9% __xfrm_lookup vmlinux
2221.00 2.6% ip_append_data vmlinux
1718.00 2.0% _raw_spin_lock_bh vmlinux
1655.00 1.9% __alloc_skb vmlinux
1572.00 1.8% sock_wfree vmlinux
1345.00 1.6% kfree vmlinux
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 04e0df8..7864d0c 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1773,12 +1773,15 @@
if (rt->fl.iif == 0)
src = rt->rt_src;
- else if (fib_lookup(dev_net(rt->dst.dev), &rt->fl, &res) == 0) {
- src = FIB_RES_PREFSRC(res);
- fib_res_put(&res);
- } else
- src = inet_select_addr(rt->dst.dev, rt->rt_gateway,
+ else {
+ rcu_read_lock();
+ if (fib_lookup(dev_net(rt->dst.dev), &rt->fl, &res) == 0)
+ src = FIB_RES_PREFSRC(res);
+ else
+ src = inet_select_addr(rt->dst.dev, rt->rt_gateway,
RT_SCOPE_UNIVERSE);
+ rcu_read_unlock();
+ }
memcpy(addr, &src, 4);
}
@@ -2081,6 +2084,7 @@
* Such approach solves two big problems:
* 1. Not simplex devices are handled properly.
* 2. IP spoofing attempts are filtered with 100% of guarantee.
+ * called with rcu_read_lock()
*/
static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
@@ -2102,7 +2106,6 @@
unsigned hash;
__be32 spec_dst;
int err = -EINVAL;
- int free_res = 0;
struct net * net = dev_net(dev);
/* IP on this device is disabled. */
@@ -2134,12 +2137,12 @@
/*
* Now we are ready to route packet.
*/
- if ((err = fib_lookup(net, &fl, &res)) != 0) {
+ err = fib_lookup(net, &fl, &res);
+ if (err != 0) {
if (!IN_DEV_FORWARD(in_dev))
goto e_hostunreach;
goto no_route;
}
- free_res = 1;
RT_CACHE_STAT_INC(in_slow_tot);
@@ -2148,8 +2151,8 @@
if (res.type == RTN_LOCAL) {
err = fib_validate_source(saddr, daddr, tos,
- net->loopback_dev->ifindex,
- dev, &spec_dst, &itag, skb->mark);
+ net->loopback_dev->ifindex,
+ dev, &spec_dst, &itag, skb->mark);
if (err < 0)
goto martian_source_keep_err;
if (err)
@@ -2164,9 +2167,6 @@
goto martian_destination;
err = ip_mkroute_input(skb, &res, &fl, in_dev, daddr, saddr, tos);
-done:
- if (free_res)
- fib_res_put(&res);
out: return err;
brd_input:
@@ -2226,7 +2226,7 @@
rth->rt_type = res.type;
hash = rt_hash(daddr, saddr, fl.iif, rt_genid(net));
err = rt_intern_hash(hash, rth, NULL, skb, fl.iif);
- goto done;
+ goto out;
no_route:
RT_CACHE_STAT_INC(in_no_route);
@@ -2249,21 +2249,21 @@
e_hostunreach:
err = -EHOSTUNREACH;
- goto done;
+ goto out;
e_inval:
err = -EINVAL;
- goto done;
+ goto out;
e_nobufs:
err = -ENOBUFS;
- goto done;
+ goto out;
martian_source:
err = -EINVAL;
martian_source_keep_err:
ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
- goto done;
+ goto out;
}
int ip_route_input_common(struct sk_buff *skb, __be32 daddr, __be32 saddr,
@@ -2349,6 +2349,7 @@
}
EXPORT_SYMBOL(ip_route_input_common);
+/* called with rcu_read_lock() */
static int __mkroute_output(struct rtable **result,
struct fib_result *res,
const struct flowi *fl,
@@ -2373,18 +2374,13 @@
if (dev_out->flags & IFF_LOOPBACK)
flags |= RTCF_LOCAL;
- rcu_read_lock();
in_dev = __in_dev_get_rcu(dev_out);
- if (!in_dev) {
- rcu_read_unlock();
+ if (!in_dev)
return -EINVAL;
- }
+
if (res->type == RTN_BROADCAST) {
flags |= RTCF_BROADCAST | RTCF_LOCAL;
- if (res->fi) {
- fib_info_put(res->fi);
- res->fi = NULL;
- }
+ res->fi = NULL;
} else if (res->type == RTN_MULTICAST) {
flags |= RTCF_MULTICAST | RTCF_LOCAL;
if (!ip_check_mc(in_dev, oldflp->fl4_dst, oldflp->fl4_src,
@@ -2394,10 +2390,8 @@
* default one, but do not gateway in this case.
* Yes, it is hack.
*/
- if (res->fi && res->prefixlen < 4) {
- fib_info_put(res->fi);
+ if (res->fi && res->prefixlen < 4)
res->fi = NULL;
- }
}
@@ -2467,6 +2461,7 @@
return 0;
}
+/* called with rcu_read_lock() */
static int ip_mkroute_output(struct rtable **rp,
struct fib_result *res,
const struct flowi *fl,
@@ -2509,7 +2504,6 @@
struct fib_result res;
unsigned int flags = 0;
struct net_device *dev_out = NULL;
- int free_res = 0;
int err;
@@ -2636,15 +2630,12 @@
err = -ENETUNREACH;
goto out;
}
- free_res = 1;
if (res.type == RTN_LOCAL) {
if (!fl.fl4_src)
fl.fl4_src = fl.fl4_dst;
dev_out = net->loopback_dev;
fl.oif = dev_out->ifindex;
- if (res.fi)
- fib_info_put(res.fi);
res.fi = NULL;
flags |= RTCF_LOCAL;
goto make_route;
@@ -2668,8 +2659,6 @@
make_route:
err = ip_mkroute_output(rp, &res, &fl, oldflp, dev_out, flags);
- if (free_res)
- fib_res_put(&res);
out: return err;
}