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From: Alexander Duyck <alexander.h.duyck@redhat.com>
Date: Thu, 22 Jan 2015 15:51:45 -0800
Subject: [PATCH] fib_trie: Various clean-ups for handling slen
While doing further work on the fib_trie I noted a few items.
First I was using calls that were far more complicated than they needed to
be for determining when to push/pull the suffix length. I have updated the
code to reflect the simplier logic.
The second issue is that I realised we weren't necessarily handling the
case of a leaf_info struct surviving a flush. I have updated the logic so
that now we will call pull_suffix in the event of having a leaf info value
left in the leaf after flushing it.
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -917,27 +917,20 @@ static void leaf_push_suffix(struct tnod
static void remove_leaf_info(struct tnode *l, struct leaf_info *old)
{
- struct hlist_node *prev;
-
- /* record the location of the pointer to this object */
- prev = rtnl_dereference(hlist_pprev_rcu(&old->hlist));
+ /* record the location of the previous list_info entry */
+ struct hlist_node **pprev = old->hlist.pprev;
+ struct leaf_info *li = hlist_entry(pprev, typeof(*li), hlist.next);
/* remove the leaf info from the list */
hlist_del_rcu(&old->hlist);
- /* if we emptied the list this leaf will be freed and we can sort
- * out parent suffix lengths as a part of trie_rebalance
- */
- if (hlist_empty(&l->list))
+ /* only access li if it is pointing at the last valid hlist_node */
+ if (hlist_empty(&l->list) || (*pprev))
return;
- /* if we removed the tail then we need to update slen */
- if (!rcu_access_pointer(hlist_next_rcu(prev))) {
- struct leaf_info *li = hlist_entry(prev, typeof(*li), hlist);
-
- l->slen = KEYLENGTH - li->plen;
- leaf_pull_suffix(l);
- }
+ /* update the trie with the latest suffix length */
+ l->slen = KEYLENGTH - li->plen;
+ leaf_pull_suffix(l);
}
static void insert_leaf_info(struct tnode *l, struct leaf_info *new)
@@ -961,7 +954,7 @@ static void insert_leaf_info(struct tnod
}
/* if we added to the tail node then we need to update slen */
- if (!rcu_access_pointer(hlist_next_rcu(&new->hlist))) {
+ if (l->slen < (KEYLENGTH - new->plen)) {
l->slen = KEYLENGTH - new->plen;
leaf_push_suffix(l);
}
@@ -1613,6 +1606,7 @@ static int trie_flush_leaf(struct tnode
struct hlist_head *lih = &l->list;
struct hlist_node *tmp;
struct leaf_info *li = NULL;
+ unsigned char plen = KEYLENGTH;
hlist_for_each_entry_safe(li, tmp, lih, hlist) {
found += trie_flush_list(&li->falh);
@@ -1620,8 +1614,14 @@ static int trie_flush_leaf(struct tnode
if (list_empty(&li->falh)) {
hlist_del_rcu(&li->hlist);
free_leaf_info(li);
+ continue;
}
+
+ plen = li->plen;
}
+
+ l->slen = KEYLENGTH - plen;
+
return found;
}
@@ -1700,13 +1700,22 @@ int fib_table_flush(struct fib_table *tb
for (l = trie_firstleaf(t); l; l = trie_nextleaf(l)) {
found += trie_flush_leaf(l);
- if (ll && hlist_empty(&ll->list))
- trie_leaf_remove(t, ll);
+ if (ll) {
+ if (hlist_empty(&ll->list))
+ trie_leaf_remove(t, ll);
+ else
+ leaf_pull_suffix(ll);
+ }
+
ll = l;
}
- if (ll && hlist_empty(&ll->list))
- trie_leaf_remove(t, ll);
+ if (ll) {
+ if (hlist_empty(&ll->list))
+ trie_leaf_remove(t, ll);
+ else
+ leaf_pull_suffix(ll);
+ }
pr_debug("trie_flush found=%d\n", found);
return found;
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