Commit 0197aa38 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 82efee14
......@@ -2487,6 +2487,7 @@ 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,
......@@ -2505,7 +2506,7 @@ 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;
......@@ -2535,7 +2536,7 @@ 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;
......@@ -2560,26 +2561,21 @@ 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)) {
......@@ -2602,10 +2598,7 @@ 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;
......@@ -2639,8 +2632,6 @@ 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;
}
......@@ -2649,10 +2640,7 @@ 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);
......@@ -2672,28 +2660,23 @@ 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))
......@@ -2724,7 +2707,10 @@ 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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