From: Alexander Duyck 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 Signed-off-by: David S. Miller --- --- 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); @@ -971,9 +976,7 @@ 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);