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Message-ID: <1285853638.2615.520.camel@edumazet-laptop>
Date: Thu, 30 Sep 2010 15:33:58 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next 2/2] ipv4: rcu conversion in ip_route_output_slow
ip_route_output_slow() is enclosed in an rcu_read_lock() protected
section, so that no references are taken/released on device, thanks to
__ip_dev_find() & dev_get_by_index_rcu()
Tested with ip route cache disabled, and a stress test :
Before patch:
elapsed time :
real 1m38.347s
user 0m11.909s
sys 23m51.501s
Profile:
13788.00 22.7% ip_route_output_slow [kernel]
7875.00 13.0% dst_destroy [kernel]
3925.00 6.5% fib_semantic_match [kernel]
3144.00 5.2% fib_rules_lookup [kernel]
3061.00 5.0% dst_alloc [kernel]
2276.00 3.7% rt_set_nexthop [kernel]
1762.00 2.9% fib_table_lookup [kernel]
1538.00 2.5% _raw_read_lock [kernel]
1358.00 2.2% ip_output [kernel]
After patch:
real 1m28.808s
user 0m13.245s
sys 20m37.293s
10950.00 17.2% ip_route_output_slow [kernel]
10726.00 16.9% dst_destroy [kernel]
5170.00 8.1% fib_semantic_match [kernel]
3937.00 6.2% dst_alloc [kernel]
3635.00 5.7% rt_set_nexthop [kernel]
2900.00 4.6% fib_rules_lookup [kernel]
2240.00 3.5% fib_table_lookup [kernel]
1427.00 2.2% _raw_read_lock [kernel]
1157.00 1.8% kmem_cache_alloc [kernel]
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
net/ipv4/route.c | 38 ++++++++++++--------------------------
1 files changed, 12 insertions(+), 26 deletions(-)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 98beda4..9b60129 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2490,6 +2490,7 @@ static int ip_mkroute_output(struct rtable **rp,
/*
* Major route resolver routine.
+ * called with rcu_read_lock();
*/
static int ip_route_output_slow(struct net *net, struct rtable **rp,
@@ -2508,7 +2509,7 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
.iif = net->loopback_dev->ifindex,
.oif = oldflp->oif };
struct fib_result res;
- unsigned flags = 0;
+ unsigned int flags = 0;
struct net_device *dev_out = NULL;
int free_res = 0;
int err;
@@ -2538,7 +2539,7 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
(ipv4_is_multicast(oldflp->fl4_dst) ||
oldflp->fl4_dst == htonl(0xFFFFFFFF))) {
/* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
- dev_out = ip_dev_find(net, oldflp->fl4_src);
+ dev_out = __ip_dev_find(net, oldflp->fl4_src, false);
if (dev_out == NULL)
goto out;
@@ -2563,26 +2564,21 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
if (!(oldflp->flags & FLOWI_FLAG_ANYSRC)) {
/* It is equivalent to inet_addr_type(saddr) == RTN_LOCAL */
- dev_out = ip_dev_find(net, oldflp->fl4_src);
- if (dev_out == NULL)
+ if (!__ip_dev_find(net, oldflp->fl4_src, false))
goto out;
- dev_put(dev_out);
- dev_out = NULL;
}
}
if (oldflp->oif) {
- dev_out = dev_get_by_index(net, oldflp->oif);
+ dev_out = dev_get_by_index_rcu(net, oldflp->oif);
err = -ENODEV;
if (dev_out == NULL)
goto out;
/* RACE: Check return value of inet_select_addr instead. */
- if (rcu_dereference_raw(dev_out->ip_ptr) == NULL) {
- dev_put(dev_out);
+ if (rcu_dereference(dev_out->ip_ptr) == NULL)
goto out; /* Wrong error code */
- }
if (ipv4_is_local_multicast(oldflp->fl4_dst) ||
oldflp->fl4_dst == htonl(0xFFFFFFFF)) {
@@ -2605,10 +2601,7 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
fl.fl4_dst = fl.fl4_src;
if (!fl.fl4_dst)
fl.fl4_dst = fl.fl4_src = htonl(INADDR_LOOPBACK);
- if (dev_out)
- dev_put(dev_out);
dev_out = net->loopback_dev;
- dev_hold(dev_out);
fl.oif = net->loopback_dev->ifindex;
res.type = RTN_LOCAL;
flags |= RTCF_LOCAL;
@@ -2642,8 +2635,6 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
res.type = RTN_UNICAST;
goto make_route;
}
- if (dev_out)
- dev_put(dev_out);
err = -ENETUNREACH;
goto out;
}
@@ -2652,10 +2643,7 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
if (res.type == RTN_LOCAL) {
if (!fl.fl4_src)
fl.fl4_src = fl.fl4_dst;
- if (dev_out)
- dev_put(dev_out);
dev_out = net->loopback_dev;
- dev_hold(dev_out);
fl.oif = dev_out->ifindex;
if (res.fi)
fib_info_put(res.fi);
@@ -2675,28 +2663,23 @@ static int ip_route_output_slow(struct net *net, struct rtable **rp,
if (!fl.fl4_src)
fl.fl4_src = FIB_RES_PREFSRC(res);
- if (dev_out)
- dev_put(dev_out);
dev_out = FIB_RES_DEV(res);
- dev_hold(dev_out);
fl.oif = dev_out->ifindex;
make_route:
err = ip_mkroute_output(rp, &res, &fl, oldflp, dev_out, flags);
-
if (free_res)
fib_res_put(&res);
- if (dev_out)
- dev_put(dev_out);
out: return err;
}
int __ip_route_output_key(struct net *net, struct rtable **rp,
const struct flowi *flp)
{
- unsigned hash;
+ unsigned int hash;
+ int res;
struct rtable *rth;
if (!rt_caching(net))
@@ -2727,7 +2710,10 @@ int __ip_route_output_key(struct net *net, struct rtable **rp,
rcu_read_unlock_bh();
slow_output:
- return ip_route_output_slow(net, rp, flp);
+ rcu_read_lock();
+ res = ip_route_output_slow(net, rp, flp);
+ rcu_read_unlock();
+ return res;
}
EXPORT_SYMBOL_GPL(__ip_route_output_key);
--
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