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Message-ID: <20141222174220.1119.91062.stgit@ahduyck-vm-fedora20>
Date: Mon, 22 Dec 2014 09:42:20 -0800
From: Alexander Duyck <alexander.h.duyck@...hat.com>
To: netdev@...r.kernel.org
Subject: [RFC PATCH 14/17] fib_trie: Push tnode flushing down to
inflate/halve
This change pushes the tnode freeing down into the inflate and halve
functions. It makes more sense here as we have a better grasp of what is
going on and when a given cluster of nodes is ready to be freed.
I believe this may address a bug in the freeing logic as well. For some
reason if the freelist got to a certain size we would call
synchronize_rcu(). I'm assuming that what they meant to do is call
synchronize_rcu() after they had handed off that much memory via
call_rcu(). As such that is what I have updated the behavior to be.
Signed-off-by: Alexander Duyck <alexander.h.duyck@...hat.com>
---
net/ipv4/fib_trie.c | 103 +++++++++++++++++++++++++--------------------------
1 file changed, 50 insertions(+), 53 deletions(-)
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 352ecf4..a41abf8 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -147,8 +147,6 @@ struct trie {
};
static void resize(struct trie *t, struct tnode *tn);
-/* tnodes to free after resize(); protected by RTNL */
-static struct callback_head *tnode_free_head;
static size_t tnode_free_size;
/*
@@ -307,32 +305,6 @@ static struct tnode *tnode_alloc(size_t size)
return vzalloc(size);
}
-static void tnode_free_safe(struct tnode *tn)
-{
- BUG_ON(IS_LEAF(tn));
- tn->rcu.next = tnode_free_head;
- tnode_free_head = &tn->rcu;
-}
-
-static void tnode_free_flush(void)
-{
- struct callback_head *head;
-
- while ((head = tnode_free_head)) {
- struct tnode *tn = container_of(head, struct tnode, rcu);
-
- tnode_free_head = head->next;
- tnode_free_size += offsetof(struct tnode, child[1 << tn->bits]);
-
- node_free(tn);
- }
-
- if (tnode_free_size >= PAGE_SIZE * sync_pages) {
- tnode_free_size = 0;
- synchronize_rcu();
- }
-}
-
static struct tnode *leaf_new(t_key key)
{
struct tnode *l = kmem_cache_alloc(trie_leaf_kmem, GFP_KERNEL);
@@ -433,17 +405,33 @@ static void put_child_root(struct tnode *tp, struct trie *t,
rcu_assign_pointer(t->trie, n);
}
-static void tnode_clean_free(struct tnode *tn)
+static inline void tnode_free_init(struct tnode *tn)
{
- struct tnode *tofree;
- unsigned long i;
+ tn->rcu.next = NULL;
+}
+
+static inline void tnode_free_append(struct tnode *tn, struct tnode *n)
+{
+ n->rcu.next = tn->rcu.next;
+ tn->rcu.next = &n->rcu;
+}
- for (i = 0; i < tnode_child_length(tn); i++) {
- tofree = tnode_get_child(tn, i);
- if (tofree)
- node_free(tofree);
+static void tnode_free(struct tnode *tn)
+{
+ struct callback_head *head = &tn->rcu;
+
+ while (head) {
+ head = head->next;
+ tnode_free_size += offsetof(struct tnode, child[1 << tn->bits]);
+ node_free(tn);
+
+ tn = container_of(head, struct tnode, rcu);
+ }
+
+ if (tnode_free_size >= PAGE_SIZE * sync_pages) {
+ tnode_free_size = 0;
+ synchronize_rcu();
}
- node_free(tn);
}
static int inflate(struct trie *t, struct tnode *oldtnode)
@@ -476,20 +464,23 @@ static int inflate(struct trie *t, struct tnode *oldtnode)
inode->bits - 1);
if (!left)
goto nomem;
+ tnode_free_append(tn, left);
right = tnode_new(inode->key | m, inode->pos,
inode->bits - 1);
- if (!right) {
- node_free(left);
+ if (!right)
goto nomem;
- }
+ tnode_free_append(tn, right);
put_child(tn, 2*i, left);
put_child(tn, 2*i+1, right);
}
}
+ /* prepare oldtnode to be freed */
+ tnode_free_init(oldtnode);
+
for (i = 0; i < olen; i++) {
struct tnode *inode = tnode_get_child(oldtnode, i);
struct tnode *left, *right;
@@ -505,12 +496,13 @@ static int inflate(struct trie *t, struct tnode *oldtnode)
continue;
}
+ /* drop the node in the old tnode free list */
+ tnode_free_append(oldtnode, inode);
+
/* An internal node with two children */
if (inode->bits == 1) {
put_child(tn, 2*i, rtnl_dereference(inode->child[0]));
put_child(tn, 2*i+1, rtnl_dereference(inode->child[1]));
-
- tnode_free_safe(inode);
continue;
}
@@ -556,17 +548,19 @@ static int inflate(struct trie *t, struct tnode *oldtnode)
put_child(tn, 2 * i, left);
put_child(tn, 2 * i + 1, right);
- tnode_free_safe(inode);
-
+ /* resize child nodes */
resize(t, left);
resize(t, right);
}
put_child_root(tp, t, tn->key, tn);
- tnode_free_safe(oldtnode);
+
+ /* we completed without error, prepare to free old node */
+ tnode_free(oldtnode);
return 0;
nomem:
- tnode_clean_free(tn);
+ /* all pointers should be clean so we are done */
+ tnode_free(tn);
return -ENOMEM;
}
@@ -599,17 +593,20 @@ static int halve(struct trie *t, struct tnode *oldtnode)
struct tnode *newn;
newn = tnode_new(left->key, oldtnode->pos, 1);
-
if (!newn) {
- tnode_clean_free(tn);
+ tnode_free(tn);
return -ENOMEM;
}
+ tnode_free_append(tn, newn);
put_child(tn, i/2, newn);
}
}
+ /* prepare oldtnode to be freed */
+ tnode_free_init(oldtnode);
+
for (i = 0; i < olen; i += 2) {
struct tnode *newBinNode;
@@ -636,11 +633,14 @@ static int halve(struct trie *t, struct tnode *oldtnode)
put_child(tn, i / 2, newBinNode);
+ /* resize child node */
resize(t, newBinNode);
}
put_child_root(tp, t, tn->key, tn);
- tnode_free_safe(oldtnode);
+
+ /* all pointers should be clean so we are done */
+ tnode_free(oldtnode);
return 0;
}
@@ -798,7 +798,8 @@ no_children:
node_set_parent(n, tp);
/* drop dead node */
- tnode_free_safe(tn);
+ tnode_free_init(tn);
+ tnode_free(tn);
}
}
@@ -884,16 +885,12 @@ static void trie_rebalance(struct trie *t, struct tnode *tn)
while ((tp = node_parent(tn)) != NULL) {
resize(t, tn);
-
- tnode_free_flush();
tn = tp;
}
/* Handle last (top) tnode */
if (IS_TNODE(tn))
resize(t, tn);
-
- tnode_free_flush();
}
/* only used from updater-side */
--
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