17afb853ee
also refresh generic patches for 3.14, 3.18, 3.19 and 4.0 targets might need a minor refresh as well, however, it looks like everything still applies cleanly with occasional small offsets. Signed-off-by: Daniel Golle <daniel@makrotopia.org> SVN-Revision: 44876
267 lines
8.1 KiB
Diff
267 lines
8.1 KiB
Diff
From: Alexander Duyck <alexander.h.duyck@redhat.com>
|
|
Date: Thu, 22 Jan 2015 15:51:14 -0800
|
|
Subject: [PATCH] fib_trie: Fix RCU bug and merge similar bits of inflate/halve
|
|
|
|
This patch addresses two issues.
|
|
|
|
The first issue is the fact that I believe I had the RCU freeing sequence
|
|
slightly out of order. As a result we could get into an issue if a caller
|
|
went into a child of a child of the new node, then backtraced into the to be
|
|
freed parent, and then attempted to access a child of a child that may have
|
|
been consumed in a resize of one of the new nodes children. To resolve this I
|
|
have moved the resize after we have freed the oldtnode. The only side effect
|
|
of this is that we will now be calling resize on more nodes in the case of
|
|
inflate due to the fact that we don't have a good way to test to see if a
|
|
full_tnode on the new node was there before or after the allocation. This
|
|
should have minimal impact however since the node should already be
|
|
correctly size so it is just the cost of calling should_inflate that we
|
|
will be taking on the node which is only a couple of cycles.
|
|
|
|
The second issue is the fact that inflate and halve were essentially doing
|
|
the same thing after the new node was added to the trie replacing the old
|
|
one. As such it wasn't really necessary to keep the code in both functions
|
|
so I have split it out into two other functions, called replace and
|
|
update_children.
|
|
|
|
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
|
|
@@ -396,8 +396,30 @@ static void put_child(struct tnode *tn,
|
|
rcu_assign_pointer(tn->child[i], n);
|
|
}
|
|
|
|
-static void put_child_root(struct tnode *tp, struct trie *t,
|
|
- t_key key, struct tnode *n)
|
|
+static void update_children(struct tnode *tn)
|
|
+{
|
|
+ unsigned long i;
|
|
+
|
|
+ /* update all of the child parent pointers */
|
|
+ for (i = tnode_child_length(tn); i;) {
|
|
+ struct tnode *inode = tnode_get_child(tn, --i);
|
|
+
|
|
+ if (!inode)
|
|
+ continue;
|
|
+
|
|
+ /* Either update the children of a tnode that
|
|
+ * already belongs to us or update the child
|
|
+ * to point to ourselves.
|
|
+ */
|
|
+ if (node_parent(inode) == tn)
|
|
+ update_children(inode);
|
|
+ else
|
|
+ node_set_parent(inode, tn);
|
|
+ }
|
|
+}
|
|
+
|
|
+static inline void put_child_root(struct tnode *tp, struct trie *t,
|
|
+ t_key key, struct tnode *n)
|
|
{
|
|
if (tp)
|
|
put_child(tp, get_index(key, tp), n);
|
|
@@ -434,10 +456,35 @@ static void tnode_free(struct tnode *tn)
|
|
}
|
|
}
|
|
|
|
+static void replace(struct trie *t, struct tnode *oldtnode, struct tnode *tn)
|
|
+{
|
|
+ struct tnode *tp = node_parent(oldtnode);
|
|
+ unsigned long i;
|
|
+
|
|
+ /* setup the parent pointer out of and back into this node */
|
|
+ NODE_INIT_PARENT(tn, tp);
|
|
+ put_child_root(tp, t, tn->key, tn);
|
|
+
|
|
+ /* update all of the child parent pointers */
|
|
+ update_children(tn);
|
|
+
|
|
+ /* all pointers should be clean so we are done */
|
|
+ tnode_free(oldtnode);
|
|
+
|
|
+ /* resize children now that oldtnode is freed */
|
|
+ for (i = tnode_child_length(tn); i;) {
|
|
+ struct tnode *inode = tnode_get_child(tn, --i);
|
|
+
|
|
+ /* resize child node */
|
|
+ if (tnode_full(tn, inode))
|
|
+ resize(t, inode);
|
|
+ }
|
|
+}
|
|
+
|
|
static int inflate(struct trie *t, struct tnode *oldtnode)
|
|
{
|
|
- struct tnode *inode, *node0, *node1, *tn, *tp;
|
|
- unsigned long i, j, k;
|
|
+ struct tnode *tn;
|
|
+ unsigned long i;
|
|
t_key m;
|
|
|
|
pr_debug("In inflate\n");
|
|
@@ -446,13 +493,18 @@ static int inflate(struct trie *t, struc
|
|
if (!tn)
|
|
return -ENOMEM;
|
|
|
|
+ /* prepare oldtnode to be freed */
|
|
+ tnode_free_init(oldtnode);
|
|
+
|
|
/* Assemble all of the pointers in our cluster, in this case that
|
|
* represents all of the pointers out of our allocated nodes that
|
|
* point to existing tnodes and the links between our allocated
|
|
* nodes.
|
|
*/
|
|
for (i = tnode_child_length(oldtnode), m = 1u << tn->pos; i;) {
|
|
- inode = tnode_get_child(oldtnode, --i);
|
|
+ struct tnode *inode = tnode_get_child(oldtnode, --i);
|
|
+ struct tnode *node0, *node1;
|
|
+ unsigned long j, k;
|
|
|
|
/* An empty child */
|
|
if (inode == NULL)
|
|
@@ -464,6 +516,9 @@ static int inflate(struct trie *t, struc
|
|
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 + 1, tnode_get_child(inode, 1));
|
|
@@ -488,9 +543,9 @@ static int inflate(struct trie *t, struc
|
|
node1 = tnode_new(inode->key | m, inode->pos, inode->bits - 1);
|
|
if (!node1)
|
|
goto nomem;
|
|
- tnode_free_append(tn, node1);
|
|
+ node0 = tnode_new(inode->key, inode->pos, inode->bits - 1);
|
|
|
|
- node0 = tnode_new(inode->key & ~m, inode->pos, inode->bits - 1);
|
|
+ tnode_free_append(tn, node1);
|
|
if (!node0)
|
|
goto nomem;
|
|
tnode_free_append(tn, node0);
|
|
@@ -512,53 +567,9 @@ static int inflate(struct trie *t, struc
|
|
put_child(tn, 2 * i, node0);
|
|
}
|
|
|
|
- /* setup the parent pointer into and out of this node */
|
|
- tp = node_parent(oldtnode);
|
|
- NODE_INIT_PARENT(tn, tp);
|
|
- put_child_root(tp, t, tn->key, tn);
|
|
+ /* setup the parent pointers into and out of this node */
|
|
+ replace(t, oldtnode, tn);
|
|
|
|
- /* prepare oldtnode to be freed */
|
|
- tnode_free_init(oldtnode);
|
|
-
|
|
- /* update all child nodes parent pointers to route to us */
|
|
- for (i = tnode_child_length(oldtnode); i;) {
|
|
- inode = tnode_get_child(oldtnode, --i);
|
|
-
|
|
- /* A leaf or an internal node with skipped bits */
|
|
- if (!tnode_full(oldtnode, inode)) {
|
|
- node_set_parent(inode, tn);
|
|
- continue;
|
|
- }
|
|
-
|
|
- /* drop the node in the old tnode free list */
|
|
- tnode_free_append(oldtnode, inode);
|
|
-
|
|
- /* fetch new nodes */
|
|
- node1 = tnode_get_child(tn, 2 * i + 1);
|
|
- node0 = tnode_get_child(tn, 2 * i);
|
|
-
|
|
- /* bits == 1 then node0 and node1 represent inode's children */
|
|
- if (inode->bits == 1) {
|
|
- node_set_parent(node1, tn);
|
|
- node_set_parent(node0, tn);
|
|
- continue;
|
|
- }
|
|
-
|
|
- /* update parent pointers in child node's children */
|
|
- for (k = tnode_child_length(inode), j = k / 2; j;) {
|
|
- node_set_parent(tnode_get_child(inode, --k), node1);
|
|
- node_set_parent(tnode_get_child(inode, --j), node0);
|
|
- node_set_parent(tnode_get_child(inode, --k), node1);
|
|
- node_set_parent(tnode_get_child(inode, --j), node0);
|
|
- }
|
|
-
|
|
- /* resize child nodes */
|
|
- resize(t, node1);
|
|
- resize(t, node0);
|
|
- }
|
|
-
|
|
- /* we completed without error, prepare to free old node */
|
|
- tnode_free(oldtnode);
|
|
return 0;
|
|
nomem:
|
|
/* all pointers should be clean so we are done */
|
|
@@ -568,7 +579,7 @@ nomem:
|
|
|
|
static int halve(struct trie *t, struct tnode *oldtnode)
|
|
{
|
|
- struct tnode *tn, *tp, *inode, *node0, *node1;
|
|
+ struct tnode *tn;
|
|
unsigned long i;
|
|
|
|
pr_debug("In halve\n");
|
|
@@ -577,14 +588,18 @@ static int halve(struct trie *t, struct
|
|
if (!tn)
|
|
return -ENOMEM;
|
|
|
|
+ /* prepare oldtnode to be freed */
|
|
+ tnode_free_init(oldtnode);
|
|
+
|
|
/* Assemble all of the pointers in our cluster, in this case that
|
|
* represents all of the pointers out of our allocated nodes that
|
|
* point to existing tnodes and the links between our allocated
|
|
* nodes.
|
|
*/
|
|
for (i = tnode_child_length(oldtnode); i;) {
|
|
- node1 = tnode_get_child(oldtnode, --i);
|
|
- node0 = tnode_get_child(oldtnode, --i);
|
|
+ struct tnode *node1 = tnode_get_child(oldtnode, --i);
|
|
+ struct tnode *node0 = tnode_get_child(oldtnode, --i);
|
|
+ struct tnode *inode;
|
|
|
|
/* At least one of the children is empty */
|
|
if (!node1 || !node0) {
|
|
@@ -609,34 +624,8 @@ static int halve(struct trie *t, struct
|
|
put_child(tn, i / 2, inode);
|
|
}
|
|
|
|
- /* setup the parent pointer out of and back into this node */
|
|
- tp = node_parent(oldtnode);
|
|
- NODE_INIT_PARENT(tn, tp);
|
|
- put_child_root(tp, t, tn->key, tn);
|
|
-
|
|
- /* prepare oldtnode to be freed */
|
|
- tnode_free_init(oldtnode);
|
|
-
|
|
- /* update all of the child parent pointers */
|
|
- for (i = tnode_child_length(tn); i;) {
|
|
- inode = tnode_get_child(tn, --i);
|
|
-
|
|
- /* only new tnodes will be considered "full" nodes */
|
|
- if (!tnode_full(tn, inode)) {
|
|
- node_set_parent(inode, tn);
|
|
- continue;
|
|
- }
|
|
-
|
|
- /* Two nonempty children */
|
|
- node_set_parent(tnode_get_child(inode, 1), inode);
|
|
- node_set_parent(tnode_get_child(inode, 0), inode);
|
|
-
|
|
- /* resize child node */
|
|
- resize(t, inode);
|
|
- }
|
|
-
|
|
- /* all pointers should be clean so we are done */
|
|
- tnode_free(oldtnode);
|
|
+ /* setup the parent pointers into and out of this node */
|
|
+ replace(t, oldtnode, tn);
|
|
|
|
return 0;
|
|
}
|