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net: ipv4: refactor ip_route_input_noref
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A later patch wants access to the fib result on an input route lookup
with the rcu lock held. Refactor ip_route_input_noref pushing the logic
between rcu_read_lock ... rcu_read_unlock into a new helper that takes
the fib_result as an input arg.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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David Ahern authored and David S. Miller committed May 26, 2017
1 parent 3abd1ad commit 5510cdf
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Showing 2 changed files with 40 additions and 29 deletions.
3 changes: 3 additions & 0 deletions include/net/route.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -178,6 +178,9 @@ static inline struct rtable *ip_route_output_gre(struct net *net, struct flowi4

int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 src,
u8 tos, struct net_device *devin);
int ip_route_input_rcu(struct sk_buff *skb, __be32 dst, __be32 src,
u8 tos, struct net_device *devin,
struct fib_result *res);

static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
u8 tos, struct net_device *devin)
Expand Down
66 changes: 37 additions & 29 deletions net/ipv4/route.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1852,9 +1852,9 @@ static int ip_mkroute_input(struct sk_buff *skb,
*/

static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
u8 tos, struct net_device *dev)
u8 tos, struct net_device *dev,
struct fib_result *res)
{
struct fib_result res;
struct in_device *in_dev = __in_dev_get_rcu(dev);
struct ip_tunnel_info *tun_info;
struct flowi4 fl4;
Expand Down Expand Up @@ -1884,8 +1884,8 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
goto martian_source;

res.fi = NULL;
res.table = NULL;
res->fi = NULL;
res->table = NULL;
if (ipv4_is_lbcast(daddr) || (saddr == 0 && daddr == 0))
goto brd_input;

Expand Down Expand Up @@ -1921,17 +1921,17 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
fl4.daddr = daddr;
fl4.saddr = saddr;
fl4.flowi4_uid = sock_net_uid(net, NULL);
err = fib_lookup(net, &fl4, &res, 0);
err = fib_lookup(net, &fl4, res, 0);
if (err != 0) {
if (!IN_DEV_FORWARD(in_dev))
err = -EHOSTUNREACH;
goto no_route;
}

if (res.type == RTN_BROADCAST)
if (res->type == RTN_BROADCAST)
goto brd_input;

if (res.type == RTN_LOCAL) {
if (res->type == RTN_LOCAL) {
err = fib_validate_source(skb, saddr, daddr, tos,
0, dev, in_dev, &itag);
if (err < 0)
Expand All @@ -1943,10 +1943,10 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
err = -EHOSTUNREACH;
goto no_route;
}
if (res.type != RTN_UNICAST)
if (res->type != RTN_UNICAST)
goto martian_destination;

err = ip_mkroute_input(skb, &res, in_dev, daddr, saddr, tos);
err = ip_mkroute_input(skb, res, in_dev, daddr, saddr, tos);
out: return err;

brd_input:
Expand All @@ -1960,14 +1960,14 @@ out: return err;
goto martian_source;
}
flags |= RTCF_BROADCAST;
res.type = RTN_BROADCAST;
res->type = RTN_BROADCAST;
RT_CACHE_STAT_INC(in_brd);

local_input:
do_cache = false;
if (res.fi) {
if (res->fi) {
if (!itag) {
rth = rcu_dereference(FIB_RES_NH(res).nh_rth_input);
rth = rcu_dereference(FIB_RES_NH(*res).nh_rth_input);
if (rt_cache_valid(rth)) {
skb_dst_set_noref(skb, &rth->dst);
err = 0;
Expand All @@ -1978,7 +1978,7 @@ out: return err;
}

rth = rt_dst_alloc(l3mdev_master_dev_rcu(dev) ? : net->loopback_dev,
flags | RTCF_LOCAL, res.type,
flags | RTCF_LOCAL, res->type,
IN_DEV_CONF_GET(in_dev, NOPOLICY), false, do_cache);
if (!rth)
goto e_nobufs;
Expand All @@ -1988,18 +1988,18 @@ out: return err;
rth->dst.tclassid = itag;
#endif
rth->rt_is_input = 1;
if (res.table)
rth->rt_table_id = res.table->tb_id;
if (res->table)
rth->rt_table_id = res->table->tb_id;

RT_CACHE_STAT_INC(in_slow_tot);
if (res.type == RTN_UNREACHABLE) {
if (res->type == RTN_UNREACHABLE) {
rth->dst.input= ip_error;
rth->dst.error= -err;
rth->rt_flags &= ~RTCF_LOCAL;
}

if (do_cache) {
struct fib_nh *nh = &FIB_RES_NH(res);
struct fib_nh *nh = &FIB_RES_NH(*res);

rth->dst.lwtstate = lwtstate_get(nh->nh_lwtstate);
if (lwtunnel_input_redirect(rth->dst.lwtstate)) {
Expand All @@ -2019,9 +2019,9 @@ out: return err;

no_route:
RT_CACHE_STAT_INC(in_no_route);
res.type = RTN_UNREACHABLE;
res.fi = NULL;
res.table = NULL;
res->type = RTN_UNREACHABLE;
res->fi = NULL;
res->table = NULL;
goto local_input;

/*
Expand Down Expand Up @@ -2051,11 +2051,22 @@ out: return err;
int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
u8 tos, struct net_device *dev)
{
int res;
struct fib_result res;
int err;

tos &= IPTOS_RT_MASK;
rcu_read_lock();
err = ip_route_input_rcu(skb, daddr, saddr, tos, dev, &res);
rcu_read_unlock();

return err;
}
EXPORT_SYMBOL(ip_route_input_noref);

/* called with rcu_read_lock held */
int ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
u8 tos, struct net_device *dev, struct fib_result *res)
{
/* Multicast recognition logic is moved from route cache to here.
The problem was that too many Ethernet cards have broken/missing
hardware multicast filters :-( As result the host on multicasting
Expand All @@ -2070,6 +2081,7 @@ int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
if (ipv4_is_multicast(daddr)) {
struct in_device *in_dev = __in_dev_get_rcu(dev);
int our = 0;
int err = -EINVAL;

if (in_dev)
our = ip_check_mc_rcu(in_dev, daddr, saddr,
Expand All @@ -2085,25 +2097,21 @@ int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
ip_hdr(skb)->protocol);
}

res = -EINVAL;
if (our
#ifdef CONFIG_IP_MROUTE
||
(!ipv4_is_local_multicast(daddr) &&
IN_DEV_MFORWARD(in_dev))
#endif
) {
res = ip_route_input_mc(skb, daddr, saddr,
err = ip_route_input_mc(skb, daddr, saddr,
tos, dev, our);
}
rcu_read_unlock();
return res;
return err;
}
res = ip_route_input_slow(skb, daddr, saddr, tos, dev);
rcu_read_unlock();
return res;

return ip_route_input_slow(skb, daddr, saddr, tos, dev, res);
}
EXPORT_SYMBOL(ip_route_input_noref);

/* called with rcu_read_lock() */
static struct rtable *__mkroute_output(const struct fib_result *res,
Expand Down

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