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openwrt/target/linux/generic/pending-3.18/080-11-fib_trie-Push-rcu_re...

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From: Alexander Duyck <alexander.h.duyck@redhat.com>
Date: Wed, 31 Dec 2014 10:56:24 -0800
Subject: [PATCH] fib_trie: Push rcu_read_lock/unlock to callers
This change is to start cleaning up some of the rcu_read_lock/unlock
handling. I realized while reviewing the code there are several spots that
I don't believe are being handled correctly or are masking warnings by
locally calling rcu_read_lock/unlock instead of calling them at the correct
level.
A common example is a call to fib_get_table followed by fib_table_lookup.
The rcu_read_lock/unlock ought to wrap both but there are several spots where
they were not wrapped.
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -222,16 +222,19 @@ static inline struct fib_table *fib_new_
static inline int fib_lookup(struct net *net, const struct flowi4 *flp,
struct fib_result *res)
{
- struct fib_table *table;
+ int err = -ENETUNREACH;
- table = fib_get_table(net, RT_TABLE_LOCAL);
- if (!fib_table_lookup(table, flp, res, FIB_LOOKUP_NOREF))
- return 0;
-
- table = fib_get_table(net, RT_TABLE_MAIN);
- if (!fib_table_lookup(table, flp, res, FIB_LOOKUP_NOREF))
- return 0;
- return -ENETUNREACH;
+ rcu_read_lock();
+
+ if (!fib_table_lookup(fib_get_table(net, RT_TABLE_LOCAL), flp, res,
+ FIB_LOOKUP_NOREF) ||
+ !fib_table_lookup(fib_get_table(net, RT_TABLE_MAIN), flp, res,
+ FIB_LOOKUP_NOREF))
+ err = 0;
+
+ rcu_read_unlock();
+
+ return err;
}
#else /* CONFIG_IP_MULTIPLE_TABLES */
@@ -247,20 +250,25 @@ static inline int fib_lookup(struct net
struct fib_result *res)
{
if (!net->ipv4.fib_has_custom_rules) {
+ int err = -ENETUNREACH;
+
+ rcu_read_lock();
+
res->tclassid = 0;
- if (net->ipv4.fib_local &&
- !fib_table_lookup(net->ipv4.fib_local, flp, res,
- FIB_LOOKUP_NOREF))
- return 0;
- if (net->ipv4.fib_main &&
- !fib_table_lookup(net->ipv4.fib_main, flp, res,
- FIB_LOOKUP_NOREF))
- return 0;
- if (net->ipv4.fib_default &&
- !fib_table_lookup(net->ipv4.fib_default, flp, res,
- FIB_LOOKUP_NOREF))
- return 0;
- return -ENETUNREACH;
+ if ((net->ipv4.fib_local &&
+ !fib_table_lookup(net->ipv4.fib_local, flp, res,
+ FIB_LOOKUP_NOREF)) ||
+ (net->ipv4.fib_main &&
+ !fib_table_lookup(net->ipv4.fib_main, flp, res,
+ FIB_LOOKUP_NOREF)) ||
+ (net->ipv4.fib_default &&
+ !fib_table_lookup(net->ipv4.fib_default, flp, res,
+ FIB_LOOKUP_NOREF)))
+ err = 0;
+
+ rcu_read_unlock();
+
+ return err;
}
return __fib_lookup(net, flp, res);
}
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -109,6 +109,7 @@ struct fib_table *fib_new_table(struct n
return tb;
}
+/* caller must hold either rtnl or rcu read lock */
struct fib_table *fib_get_table(struct net *net, u32 id)
{
struct fib_table *tb;
@@ -119,15 +120,11 @@ struct fib_table *fib_get_table(struct n
id = RT_TABLE_MAIN;
h = id & (FIB_TABLE_HASHSZ - 1);
- rcu_read_lock();
head = &net->ipv4.fib_table_hash[h];
hlist_for_each_entry_rcu(tb, head, tb_hlist) {
- if (tb->tb_id == id) {
- rcu_read_unlock();
+ if (tb->tb_id == id)
return tb;
- }
}
- rcu_read_unlock();
return NULL;
}
#endif /* CONFIG_IP_MULTIPLE_TABLES */
@@ -167,16 +164,18 @@ static inline unsigned int __inet_dev_ad
if (ipv4_is_multicast(addr))
return RTN_MULTICAST;
+ rcu_read_lock();
+
local_table = fib_get_table(net, RT_TABLE_LOCAL);
if (local_table) {
ret = RTN_UNICAST;
- rcu_read_lock();
if (!fib_table_lookup(local_table, &fl4, &res, FIB_LOOKUP_NOREF)) {
if (!dev || dev == res.fi->fib_dev)
ret = res.type;
}
- rcu_read_unlock();
}
+
+ rcu_read_unlock();
return ret;
}
@@ -923,7 +922,7 @@ no_promotions:
#undef BRD1_OK
}
-static void nl_fib_lookup(struct fib_result_nl *frn, struct fib_table *tb)
+static void nl_fib_lookup(struct net *net, struct fib_result_nl *frn)
{
struct fib_result res;
@@ -933,6 +932,11 @@ static void nl_fib_lookup(struct fib_res
.flowi4_tos = frn->fl_tos,
.flowi4_scope = frn->fl_scope,
};
+ struct fib_table *tb;
+
+ rcu_read_lock();
+
+ tb = fib_get_table(net, frn->tb_id_in);
frn->err = -ENOENT;
if (tb) {
@@ -949,6 +953,8 @@ static void nl_fib_lookup(struct fib_res
}
local_bh_enable();
}
+
+ rcu_read_unlock();
}
static void nl_fib_input(struct sk_buff *skb)
@@ -956,7 +962,6 @@ static void nl_fib_input(struct sk_buff
struct net *net;
struct fib_result_nl *frn;
struct nlmsghdr *nlh;
- struct fib_table *tb;
u32 portid;
net = sock_net(skb->sk);
@@ -972,9 +977,7 @@ static void nl_fib_input(struct sk_buff
nlh = nlmsg_hdr(skb);
frn = (struct fib_result_nl *) nlmsg_data(nlh);
- tb = fib_get_table(net, frn->tb_id_in);
-
- nl_fib_lookup(frn, tb);
+ nl_fib_lookup(net, frn);
portid = NETLINK_CB(skb).portid; /* netlink portid */
NETLINK_CB(skb).portid = 0; /* from kernel */
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -81,27 +81,25 @@ static int fib4_rule_action(struct fib_r
break;
case FR_ACT_UNREACHABLE:
- err = -ENETUNREACH;
- goto errout;
+ return -ENETUNREACH;
case FR_ACT_PROHIBIT:
- err = -EACCES;
- goto errout;
+ return -EACCES;
case FR_ACT_BLACKHOLE:
default:
- err = -EINVAL;
- goto errout;
+ return -EINVAL;
}
+ rcu_read_lock();
+
tbl = fib_get_table(rule->fr_net, rule->table);
- if (!tbl)
- goto errout;
+ if (tbl)
+ err = fib_table_lookup(tbl, &flp->u.ip4,
+ (struct fib_result *)arg->result,
+ arg->flags);
- err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
- if (err > 0)
- err = -EAGAIN;
-errout:
+ rcu_read_unlock();
return err;
}
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1181,72 +1181,6 @@ err:
return err;
}
-/* should be called with rcu_read_lock */
-static int check_leaf(struct fib_table *tb, struct trie *t, struct tnode *l,
- t_key key, const struct flowi4 *flp,
- struct fib_result *res, int fib_flags)
-{
- struct leaf_info *li;
- struct hlist_head *hhead = &l->list;
-
- hlist_for_each_entry_rcu(li, hhead, hlist) {
- struct fib_alias *fa;
-
- if (l->key != (key & li->mask_plen))
- continue;
-
- list_for_each_entry_rcu(fa, &li->falh, fa_list) {
- struct fib_info *fi = fa->fa_info;
- int nhsel, err;
-
- if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
- continue;
- if (fi->fib_dead)
- continue;
- if (fa->fa_info->fib_scope < flp->flowi4_scope)
- continue;
- fib_alias_accessed(fa);
- err = fib_props[fa->fa_type].error;
- if (unlikely(err < 0)) {
-#ifdef CONFIG_IP_FIB_TRIE_STATS
- this_cpu_inc(t->stats->semantic_match_passed);
-#endif
- return err;
- }
- if (fi->fib_flags & RTNH_F_DEAD)
- continue;
- for (nhsel = 0; nhsel < fi->fib_nhs; nhsel++) {
- const struct fib_nh *nh = &fi->fib_nh[nhsel];
-
- if (nh->nh_flags & RTNH_F_DEAD)
- continue;
- if (flp->flowi4_oif && flp->flowi4_oif != nh->nh_oif)
- continue;
-
-#ifdef CONFIG_IP_FIB_TRIE_STATS
- this_cpu_inc(t->stats->semantic_match_passed);
-#endif
- res->prefixlen = li->plen;
- res->nh_sel = nhsel;
- res->type = fa->fa_type;
- res->scope = fi->fib_scope;
- res->fi = fi;
- res->table = tb;
- res->fa_head = &li->falh;
- if (!(fib_flags & FIB_LOOKUP_NOREF))
- atomic_inc(&fi->fib_clntref);
- return 0;
- }
- }
-
-#ifdef CONFIG_IP_FIB_TRIE_STATS
- this_cpu_inc(t->stats->semantic_match_miss);
-#endif
- }
-
- return 1;
-}
-
static inline t_key prefix_mismatch(t_key key, struct tnode *n)
{
t_key prefix = n->key;
@@ -1254,6 +1188,7 @@ static inline t_key prefix_mismatch(t_ke
return (key ^ prefix) & (prefix | -prefix);
}
+/* should be called with rcu_read_lock */
int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
struct fib_result *res, int fib_flags)
{
@@ -1263,14 +1198,12 @@ int fib_table_lookup(struct fib_table *t
#endif
const t_key key = ntohl(flp->daddr);
struct tnode *n, *pn;
+ struct leaf_info *li;
t_key cindex;
- int ret = 1;
-
- rcu_read_lock();
n = rcu_dereference(t->trie);
if (!n)
- goto failed;
+ return -EAGAIN;
#ifdef CONFIG_IP_FIB_TRIE_STATS
this_cpu_inc(stats->gets);
@@ -1350,7 +1283,7 @@ backtrace:
pn = node_parent_rcu(pn);
if (unlikely(!pn))
- goto failed;
+ return -EAGAIN;
#ifdef CONFIG_IP_FIB_TRIE_STATS
this_cpu_inc(stats->backtrack);
#endif
@@ -1368,12 +1301,62 @@ backtrace:
found:
/* Step 3: Process the leaf, if that fails fall back to backtracing */
- ret = check_leaf(tb, t, n, key, flp, res, fib_flags);
- if (unlikely(ret > 0))
- goto backtrace;
-failed:
- rcu_read_unlock();
- return ret;
+ hlist_for_each_entry_rcu(li, &n->list, hlist) {
+ struct fib_alias *fa;
+
+ if ((key ^ n->key) & li->mask_plen)
+ continue;
+
+ list_for_each_entry_rcu(fa, &li->falh, fa_list) {
+ struct fib_info *fi = fa->fa_info;
+ int nhsel, err;
+
+ if (fa->fa_tos && fa->fa_tos != flp->flowi4_tos)
+ continue;
+ if (fi->fib_dead)
+ continue;
+ if (fa->fa_info->fib_scope < flp->flowi4_scope)
+ continue;
+ fib_alias_accessed(fa);
+ err = fib_props[fa->fa_type].error;
+ if (unlikely(err < 0)) {
+#ifdef CONFIG_IP_FIB_TRIE_STATS
+ this_cpu_inc(stats->semantic_match_passed);
+#endif
+ return err;
+ }
+ if (fi->fib_flags & RTNH_F_DEAD)
+ continue;
+ for (nhsel = 0; nhsel < fi->fib_nhs; nhsel++) {
+ const struct fib_nh *nh = &fi->fib_nh[nhsel];
+
+ if (nh->nh_flags & RTNH_F_DEAD)
+ continue;
+ if (flp->flowi4_oif && flp->flowi4_oif != nh->nh_oif)
+ continue;
+
+ if (!(fib_flags & FIB_LOOKUP_NOREF))
+ atomic_inc(&fi->fib_clntref);
+
+ res->prefixlen = li->plen;
+ res->nh_sel = nhsel;
+ res->type = fa->fa_type;
+ res->scope = fi->fib_scope;
+ res->fi = fi;
+ res->table = tb;
+ res->fa_head = &li->falh;
+#ifdef CONFIG_IP_FIB_TRIE_STATS
+ this_cpu_inc(stats->semantic_match_passed);
+#endif
+ return err;
+ }
+ }
+
+#ifdef CONFIG_IP_FIB_TRIE_STATS
+ this_cpu_inc(stats->semantic_match_miss);
+#endif
+ }
+ goto backtrace;
}
EXPORT_SYMBOL_GPL(fib_table_lookup);
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