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git://git.openwrt.org/openwrt/openwrt.git
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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
346 lines
10 KiB
Diff
346 lines
10 KiB
Diff
From: Alexander Duyck <alexander.h.duyck@redhat.com>
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Date: Wed, 31 Dec 2014 10:56:55 -0800
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Subject: [PATCH] fib_trie: inflate/halve nodes in a more RCU friendly
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way
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This change pulls the node_set_parent functionality out of put_child_reorg
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and instead leaves that to the function to take care of as well. By doing
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this we can fully construct the new cluster of tnodes and all of the
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pointers out of it before we start routing pointers into it.
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I am suspecting this will likely fix some concurency issues though I don't
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have a good test to show as such.
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Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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--- a/net/ipv4/fib_trie.c
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+++ b/net/ipv4/fib_trie.c
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@@ -391,8 +391,6 @@ static void put_child(struct tnode *tn,
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else if (!wasfull && isfull)
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tn->full_children++;
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- node_set_parent(n, tn);
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-
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rcu_assign_pointer(tn->child[i], n);
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}
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@@ -436,10 +434,8 @@ static void tnode_free(struct tnode *tn)
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static int inflate(struct trie *t, struct tnode *oldtnode)
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{
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- unsigned long olen = tnode_child_length(oldtnode);
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- struct tnode *tp = node_parent(oldtnode);
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- struct tnode *tn;
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- unsigned long i;
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+ struct tnode *inode, *node0, *node1, *tn, *tp;
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+ unsigned long i, j, k;
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t_key m;
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pr_debug("In inflate\n");
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@@ -448,43 +444,13 @@ static int inflate(struct trie *t, struc
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if (!tn)
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return -ENOMEM;
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- /*
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- * Preallocate and store tnodes before the actual work so we
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- * don't get into an inconsistent state if memory allocation
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- * fails. In case of failure we return the oldnode and inflate
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- * of tnode is ignored.
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+ /* Assemble all of the pointers in our cluster, in this case that
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+ * represents all of the pointers out of our allocated nodes that
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+ * point to existing tnodes and the links between our allocated
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+ * nodes.
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*/
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- for (i = 0, m = 1u << tn->pos; i < olen; i++) {
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- struct tnode *inode = tnode_get_child(oldtnode, i);
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-
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- if (tnode_full(oldtnode, inode) && (inode->bits > 1)) {
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- struct tnode *left, *right;
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-
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- left = tnode_new(inode->key & ~m, inode->pos,
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- inode->bits - 1);
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- if (!left)
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- goto nomem;
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- tnode_free_append(tn, left);
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-
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- right = tnode_new(inode->key | m, inode->pos,
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- inode->bits - 1);
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-
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- if (!right)
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- goto nomem;
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- tnode_free_append(tn, right);
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-
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- put_child(tn, 2*i, left);
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- put_child(tn, 2*i+1, right);
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- }
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- }
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-
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- /* prepare oldtnode to be freed */
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- tnode_free_init(oldtnode);
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-
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- for (i = 0; i < olen; i++) {
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- struct tnode *inode = tnode_get_child(oldtnode, i);
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- struct tnode *left, *right;
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- unsigned long size, j;
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+ for (i = tnode_child_length(oldtnode), m = 1u << tn->pos; i;) {
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+ inode = tnode_get_child(oldtnode, --i);
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/* An empty child */
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if (inode == NULL)
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@@ -496,65 +462,99 @@ static int inflate(struct trie *t, struc
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continue;
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}
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- /* drop the node in the old tnode free list */
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- tnode_free_append(oldtnode, inode);
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-
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/* An internal node with two children */
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if (inode->bits == 1) {
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- put_child(tn, 2*i, rtnl_dereference(inode->child[0]));
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- put_child(tn, 2*i+1, rtnl_dereference(inode->child[1]));
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+ put_child(tn, 2 * i + 1, tnode_get_child(inode, 1));
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+ put_child(tn, 2 * i, tnode_get_child(inode, 0));
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continue;
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}
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- /* An internal node with more than two children */
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-
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/* We will replace this node 'inode' with two new
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- * ones, 'left' and 'right', each with half of the
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+ * ones, 'node0' and 'node1', each with half of the
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* original children. The two new nodes will have
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* a position one bit further down the key and this
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* means that the "significant" part of their keys
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* (see the discussion near the top of this file)
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* will differ by one bit, which will be "0" in
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- * left's key and "1" in right's key. Since we are
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+ * node0's key and "1" in node1's key. Since we are
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* moving the key position by one step, the bit that
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* we are moving away from - the bit at position
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- * (inode->pos) - is the one that will differ between
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- * left and right. So... we synthesize that bit in the
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- * two new keys.
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- * The mask 'm' below will be a single "one" bit at
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- * the position (inode->pos)
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+ * (tn->pos) - is the one that will differ between
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+ * node0 and node1. So... we synthesize that bit in the
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+ * two new keys.
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*/
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+ node1 = tnode_new(inode->key | m, inode->pos, inode->bits - 1);
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+ if (!node1)
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+ goto nomem;
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+ tnode_free_append(tn, node1);
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+
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+ node0 = tnode_new(inode->key & ~m, inode->pos, inode->bits - 1);
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+ if (!node0)
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+ goto nomem;
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+ tnode_free_append(tn, node0);
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+
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+ /* populate child pointers in new nodes */
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+ for (k = tnode_child_length(inode), j = k / 2; j;) {
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+ put_child(node1, --j, tnode_get_child(inode, --k));
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+ put_child(node0, j, tnode_get_child(inode, j));
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+ put_child(node1, --j, tnode_get_child(inode, --k));
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+ put_child(node0, j, tnode_get_child(inode, j));
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+ }
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+
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+ /* link new nodes to parent */
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+ NODE_INIT_PARENT(node1, tn);
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+ NODE_INIT_PARENT(node0, tn);
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+
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+ /* link parent to nodes */
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+ put_child(tn, 2 * i + 1, node1);
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+ put_child(tn, 2 * i, node0);
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+ }
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+
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+ /* setup the parent pointer into and out of this node */
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+ tp = node_parent(oldtnode);
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+ NODE_INIT_PARENT(tn, tp);
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+ put_child_root(tp, t, tn->key, tn);
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- /* Use the old key, but set the new significant
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- * bit to zero.
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- */
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+ /* prepare oldtnode to be freed */
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+ tnode_free_init(oldtnode);
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- left = tnode_get_child(tn, 2*i);
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- put_child(tn, 2*i, NULL);
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+ /* update all child nodes parent pointers to route to us */
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+ for (i = tnode_child_length(oldtnode); i;) {
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+ inode = tnode_get_child(oldtnode, --i);
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- BUG_ON(!left);
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+ /* A leaf or an internal node with skipped bits */
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+ if (!tnode_full(oldtnode, inode)) {
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+ node_set_parent(inode, tn);
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+ continue;
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+ }
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- right = tnode_get_child(tn, 2*i+1);
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- put_child(tn, 2*i+1, NULL);
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+ /* drop the node in the old tnode free list */
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+ tnode_free_append(oldtnode, inode);
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- BUG_ON(!right);
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+ /* fetch new nodes */
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+ node1 = tnode_get_child(tn, 2 * i + 1);
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+ node0 = tnode_get_child(tn, 2 * i);
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- size = tnode_child_length(left);
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- for (j = 0; j < size; j++) {
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- put_child(left, j, rtnl_dereference(inode->child[j]));
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- put_child(right, j, rtnl_dereference(inode->child[j + size]));
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+ /* bits == 1 then node0 and node1 represent inode's children */
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+ if (inode->bits == 1) {
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+ node_set_parent(node1, tn);
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+ node_set_parent(node0, tn);
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+ continue;
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}
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- put_child(tn, 2 * i, left);
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- put_child(tn, 2 * i + 1, right);
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+ /* update parent pointers in child node's children */
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+ for (k = tnode_child_length(inode), j = k / 2; j;) {
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+ node_set_parent(tnode_get_child(inode, --k), node1);
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+ node_set_parent(tnode_get_child(inode, --j), node0);
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+ node_set_parent(tnode_get_child(inode, --k), node1);
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+ node_set_parent(tnode_get_child(inode, --j), node0);
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+ }
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/* resize child nodes */
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- resize(t, left);
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- resize(t, right);
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+ resize(t, node1);
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+ resize(t, node0);
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}
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- put_child_root(tp, t, tn->key, tn);
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-
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/* we completed without error, prepare to free old node */
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tnode_free(oldtnode);
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return 0;
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@@ -566,10 +566,8 @@ nomem:
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static int halve(struct trie *t, struct tnode *oldtnode)
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{
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- unsigned long olen = tnode_child_length(oldtnode);
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- struct tnode *tp = node_parent(oldtnode);
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- struct tnode *tn, *left, *right;
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- int i;
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+ struct tnode *tn, *tp, *inode, *node0, *node1;
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+ unsigned long i;
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pr_debug("In halve\n");
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@@ -577,68 +575,64 @@ static int halve(struct trie *t, struct
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if (!tn)
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return -ENOMEM;
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- /*
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- * Preallocate and store tnodes before the actual work so we
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- * don't get into an inconsistent state if memory allocation
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- * fails. In case of failure we return the oldnode and halve
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- * of tnode is ignored.
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+ /* Assemble all of the pointers in our cluster, in this case that
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+ * represents all of the pointers out of our allocated nodes that
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+ * point to existing tnodes and the links between our allocated
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+ * nodes.
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*/
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+ for (i = tnode_child_length(oldtnode); i;) {
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+ node1 = tnode_get_child(oldtnode, --i);
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+ node0 = tnode_get_child(oldtnode, --i);
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- for (i = 0; i < olen; i += 2) {
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- left = tnode_get_child(oldtnode, i);
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- right = tnode_get_child(oldtnode, i+1);
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+ /* At least one of the children is empty */
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+ if (!node1 || !node0) {
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+ put_child(tn, i / 2, node1 ? : node0);
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+ continue;
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+ }
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/* Two nonempty children */
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- if (left && right) {
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- struct tnode *newn;
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-
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- newn = tnode_new(left->key, oldtnode->pos, 1);
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- if (!newn) {
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- tnode_free(tn);
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- return -ENOMEM;
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- }
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- tnode_free_append(tn, newn);
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-
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- put_child(tn, i/2, newn);
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+ inode = tnode_new(node0->key, oldtnode->pos, 1);
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+ if (!inode) {
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+ tnode_free(tn);
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+ return -ENOMEM;
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}
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+ tnode_free_append(tn, inode);
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+ /* initialize pointers out of node */
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+ put_child(inode, 1, node1);
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+ put_child(inode, 0, node0);
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+ NODE_INIT_PARENT(inode, tn);
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+
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+ /* link parent to node */
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+ put_child(tn, i / 2, inode);
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}
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+ /* setup the parent pointer out of and back into this node */
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+ tp = node_parent(oldtnode);
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+ NODE_INIT_PARENT(tn, tp);
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+ put_child_root(tp, t, tn->key, tn);
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+
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/* prepare oldtnode to be freed */
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tnode_free_init(oldtnode);
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- for (i = 0; i < olen; i += 2) {
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- struct tnode *newBinNode;
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-
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- left = tnode_get_child(oldtnode, i);
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- right = tnode_get_child(oldtnode, i+1);
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-
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- /* At least one of the children is empty */
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- if (left == NULL) {
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- if (right == NULL) /* Both are empty */
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- continue;
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- put_child(tn, i/2, right);
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- continue;
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- }
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-
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- if (right == NULL) {
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- put_child(tn, i/2, left);
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+ /* update all of the child parent pointers */
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+ for (i = tnode_child_length(tn); i;) {
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+ inode = tnode_get_child(tn, --i);
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+
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+ /* only new tnodes will be considered "full" nodes */
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+ if (!tnode_full(tn, inode)) {
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+ node_set_parent(inode, tn);
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continue;
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}
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/* Two nonempty children */
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- newBinNode = tnode_get_child(tn, i/2);
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- put_child(newBinNode, 0, left);
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- put_child(newBinNode, 1, right);
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-
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- put_child(tn, i / 2, newBinNode);
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+ node_set_parent(tnode_get_child(inode, 1), inode);
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+ node_set_parent(tnode_get_child(inode, 0), inode);
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/* resize child node */
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- resize(t, newBinNode);
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+ resize(t, inode);
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}
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- put_child_root(tp, t, tn->key, tn);
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-
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/* all pointers should be clean so we are done */
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tnode_free(oldtnode);
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