[net-next PATCH 16/17] fib_trie: Remove checks for index >= tnode_child_length from tnode_get_child
From: Alexander Duyck <hidden>
Date: 2014-12-31 18:57:03
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
For some reason the compiler doesn't seem to understand that when we are in a loop that runs from tnode_child_length - 1 to 0 we don't expect the value of tn->bits to change. As such every call to tnode_get_child was rerunning tnode_chile_length which ended up consuming quite a bit of space in the resultant assembly code. I have gone though and verified that in all cases where tnode_get_child is used we are either winding though a fixed loop from tnode_child_length - 1 to 0, or are in a fastpath case where we are verifying the value by either checking for any remaining bits after shifting index by bits and testing for leaf, or by using tnode_child_length. size net/ipv4/fib_trie.o Before: text data bss dec hex filename 15506 376 8 15890 3e12 net/ipv4/fib_trie.o After: text data bss dec hex filename 14827 376 8 15211 3b6b net/ipv4/fib_trie.o Signed-off-by: Alexander Duyck <redacted> --- net/ipv4/fib_trie.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-)
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 0c88df0..87fc9a4 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c@@ -186,8 +186,6 @@ static inline unsigned long tnode_child_length(const struct tnode *tn) static inline struct tnode *tnode_get_child(const struct tnode *tn, unsigned long i) { - BUG_ON(i >= tnode_child_length(tn)); - return rtnl_dereference(tn->child[i]); }
@@ -195,8 +193,6 @@ static inline struct tnode *tnode_get_child(const struct tnode *tn, static inline struct tnode *tnode_get_child_rcu(const struct tnode *tn, unsigned long i) { - BUG_ON(i >= tnode_child_length(tn)); - return rcu_dereference_rtnl(tn->child[i]); }
@@ -371,7 +367,7 @@ static inline int tnode_full(const struct tnode *tn, const struct tnode *n) */ static void put_child(struct tnode *tn, unsigned long i, struct tnode *n) { - struct tnode *chi = rtnl_dereference(tn->child[i]); + struct tnode *chi = tnode_get_child(tn, i); int isfull, wasfull; BUG_ON(i >= tnode_child_length(tn));
@@ -867,7 +863,7 @@ static struct tnode *fib_find_node(struct trie *t, u32 key) if (IS_LEAF(n)) break; - n = rcu_dereference_rtnl(n->child[index]); + n = tnode_get_child_rcu(n, index); } return n;
@@ -934,7 +930,7 @@ static struct list_head *fib_insert_node(struct trie *t, u32 key, int plen) } tp = n; - n = rcu_dereference_rtnl(n->child[index]); + n = tnode_get_child_rcu(n, index); } l = leaf_new(key);
@@ -1215,7 +1211,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp, cindex = index; } - n = rcu_dereference(n->child[index]); + n = tnode_get_child_rcu(n, index); if (unlikely(!n)) goto backtrace; }
@@ -1835,7 +1831,7 @@ static void trie_collect_stats(struct trie *t, struct trie_stat *s) if (n->bits < MAX_STAT_DEPTH) s->nodesizes[n->bits]++; - for (i = 0; i < tnode_child_length(n); i++) { + for (i = tnode_child_length(n); i--;) { if (!rcu_access_pointer(n->child[i])) s->nullpointers++; }