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-rw-r--r--target/linux/generic/patches-3.18/080-14-fib_trie-Push-assignment-of-child-to-parent-down-int.patch336
1 files changed, 336 insertions, 0 deletions
diff --git a/target/linux/generic/patches-3.18/080-14-fib_trie-Push-assignment-of-child-to-parent-down-int.patch b/target/linux/generic/patches-3.18/080-14-fib_trie-Push-assignment-of-child-to-parent-down-int.patch
new file mode 100644
index 0000000000..0e87a7d08e
--- /dev/null
+++ b/target/linux/generic/patches-3.18/080-14-fib_trie-Push-assignment-of-child-to-parent-down-int.patch
@@ -0,0 +1,336 @@
+From: Alexander Duyck <alexander.h.duyck@redhat.com>
+Date: Wed, 31 Dec 2014 10:56:43 -0800
+Subject: [PATCH] fib_trie: Push assignment of child to parent down into
+ inflate/halve
+
+This change makes it so that the assignment of the tnode to the parent is
+handled directly within whatever function is currently handling the node be
+it inflate, halve, or resize. By doing this we can avoid some of the need
+to set NULL pointers in the tree while we are resizing the subnodes.
+
+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
+@@ -146,9 +146,7 @@ struct trie {
+ #endif
+ };
+
+-static void tnode_put_child_reorg(struct tnode *tn, unsigned long i,
+- struct tnode *n, int wasfull);
+-static struct tnode *resize(struct trie *t, struct tnode *tn);
++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;
+@@ -396,22 +394,13 @@ static inline int tnode_full(const struc
+ return n && ((n->pos + n->bits) == tn->pos) && IS_TNODE(n);
+ }
+
+-static inline void put_child(struct tnode *tn, unsigned long i,
+- struct tnode *n)
+-{
+- tnode_put_child_reorg(tn, i, n, -1);
+-}
+-
+- /*
+- * Add a child at position i overwriting the old value.
+- * Update the value of full_children and empty_children.
+- */
+-
+-static void tnode_put_child_reorg(struct tnode *tn, unsigned long i,
+- struct tnode *n, int wasfull)
++/* Add a child at position i overwriting the old value.
++ * Update the value of full_children and empty_children.
++ */
++static void put_child(struct tnode *tn, unsigned long i, struct tnode *n)
+ {
+ struct tnode *chi = rtnl_dereference(tn->child[i]);
+- int isfull;
++ int isfull, wasfull;
+
+ BUG_ON(i >= tnode_child_length(tn));
+
+@@ -422,10 +411,9 @@ static void tnode_put_child_reorg(struct
+ tn->empty_children--;
+
+ /* update fullChildren */
+- if (wasfull == -1)
+- wasfull = tnode_full(tn, chi);
+-
++ wasfull = tnode_full(tn, chi);
+ isfull = tnode_full(tn, n);
++
+ if (wasfull && !isfull)
+ tn->full_children--;
+ else if (!wasfull && isfull)
+@@ -458,9 +446,10 @@ static void tnode_clean_free(struct tnod
+ node_free(tn);
+ }
+
+-static struct tnode *inflate(struct trie *t, struct tnode *oldtnode)
++static int inflate(struct trie *t, struct tnode *oldtnode)
+ {
+ unsigned long olen = tnode_child_length(oldtnode);
++ struct tnode *tp = node_parent(oldtnode);
+ struct tnode *tn;
+ unsigned long i;
+ t_key m;
+@@ -468,9 +457,8 @@ static struct tnode *inflate(struct trie
+ pr_debug("In inflate\n");
+
+ tn = tnode_new(oldtnode->key, oldtnode->pos - 1, oldtnode->bits + 1);
+-
+ if (!tn)
+- return ERR_PTR(-ENOMEM);
++ return -ENOMEM;
+
+ /*
+ * Preallocate and store tnodes before the actual work so we
+@@ -564,30 +552,36 @@ static struct tnode *inflate(struct trie
+ put_child(left, j, rtnl_dereference(inode->child[j]));
+ put_child(right, j, rtnl_dereference(inode->child[j + size]));
+ }
+- put_child(tn, 2*i, resize(t, left));
+- put_child(tn, 2*i+1, resize(t, right));
++
++ put_child(tn, 2 * i, left);
++ put_child(tn, 2 * i + 1, right);
+
+ tnode_free_safe(inode);
++
++ resize(t, left);
++ resize(t, right);
+ }
++
++ put_child_root(tp, t, tn->key, tn);
+ tnode_free_safe(oldtnode);
+- return tn;
++ return 0;
+ nomem:
+ tnode_clean_free(tn);
+- return ERR_PTR(-ENOMEM);
++ return -ENOMEM;
+ }
+
+-static struct tnode *halve(struct trie *t, struct tnode *oldtnode)
++static int halve(struct trie *t, struct tnode *oldtnode)
+ {
+ unsigned long olen = tnode_child_length(oldtnode);
++ struct tnode *tp = node_parent(oldtnode);
+ struct tnode *tn, *left, *right;
+ int i;
+
+ pr_debug("In halve\n");
+
+ tn = tnode_new(oldtnode->key, oldtnode->pos + 1, oldtnode->bits - 1);
+-
+ if (!tn)
+- return ERR_PTR(-ENOMEM);
++ return -ENOMEM;
+
+ /*
+ * Preallocate and store tnodes before the actual work so we
+@@ -606,8 +600,10 @@ static struct tnode *halve(struct trie *
+
+ newn = tnode_new(left->key, oldtnode->pos, 1);
+
+- if (!newn)
+- goto nomem;
++ if (!newn) {
++ tnode_clean_free(tn);
++ return -ENOMEM;
++ }
+
+ put_child(tn, i/2, newn);
+ }
+@@ -635,16 +631,18 @@ static struct tnode *halve(struct trie *
+
+ /* Two nonempty children */
+ newBinNode = tnode_get_child(tn, i/2);
+- put_child(tn, i/2, NULL);
+ put_child(newBinNode, 0, left);
+ put_child(newBinNode, 1, right);
+- put_child(tn, i/2, resize(t, newBinNode));
++
++ put_child(tn, i / 2, newBinNode);
++
++ resize(t, newBinNode);
+ }
++
++ put_child_root(tp, t, tn->key, tn);
+ tnode_free_safe(oldtnode);
+- return tn;
+-nomem:
+- tnode_clean_free(tn);
+- return ERR_PTR(-ENOMEM);
++
++ return 0;
+ }
+
+ /* From "Implementing a dynamic compressed trie" by Stefan Nilsson of
+@@ -704,45 +702,48 @@ nomem:
+ * tnode_child_length(tn)
+ *
+ */
+-static bool should_inflate(const struct tnode *tn)
++static bool should_inflate(const struct tnode *tp, const struct tnode *tn)
+ {
+ unsigned long used = tnode_child_length(tn);
+ unsigned long threshold = used;
+
+ /* Keep root node larger */
+- threshold *= node_parent(tn) ? inflate_threshold :
+- inflate_threshold_root;
++ threshold *= tp ? inflate_threshold : inflate_threshold_root;
+ used += tn->full_children;
+ used -= tn->empty_children;
+
+ return tn->pos && ((50 * used) >= threshold);
+ }
+
+-static bool should_halve(const struct tnode *tn)
++static bool should_halve(const struct tnode *tp, const struct tnode *tn)
+ {
+ unsigned long used = tnode_child_length(tn);
+ unsigned long threshold = used;
+
+ /* Keep root node larger */
+- threshold *= node_parent(tn) ? halve_threshold :
+- halve_threshold_root;
++ threshold *= tp ? halve_threshold : halve_threshold_root;
+ used -= tn->empty_children;
+
+ return (tn->bits > 1) && ((100 * used) < threshold);
+ }
+
+ #define MAX_WORK 10
+-static struct tnode *resize(struct trie *t, struct tnode *tn)
++static void resize(struct trie *t, struct tnode *tn)
+ {
+- struct tnode *old_tn, *n = NULL;
++ struct tnode *tp = node_parent(tn), *n = NULL;
++ struct tnode __rcu **cptr;
+ int max_work;
+
+- if (!tn)
+- return NULL;
+-
+ pr_debug("In tnode_resize %p inflate_threshold=%d threshold=%d\n",
+ tn, inflate_threshold, halve_threshold);
+
++ /* track the tnode via the pointer from the parent instead of
++ * doing it ourselves. This way we can let RCU fully do its
++ * thing without us interfering
++ */
++ cptr = tp ? &tp->child[get_index(tn->key, tp)] : &t->trie;
++ BUG_ON(tn != rtnl_dereference(*cptr));
++
+ /* No children */
+ if (tn->empty_children > (tnode_child_length(tn) - 1))
+ goto no_children;
+@@ -755,39 +756,35 @@ static struct tnode *resize(struct trie
+ * nonempty nodes that are above the threshold.
+ */
+ max_work = MAX_WORK;
+- while (should_inflate(tn) && max_work--) {
+- old_tn = tn;
+- tn = inflate(t, tn);
+-
+- if (IS_ERR(tn)) {
+- tn = old_tn;
++ while (should_inflate(tp, tn) && max_work--) {
++ if (inflate(t, tn)) {
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+ this_cpu_inc(t->stats->resize_node_skipped);
+ #endif
+ break;
+ }
++
++ tn = rtnl_dereference(*cptr);
+ }
+
+ /* Return if at least one inflate is run */
+ if (max_work != MAX_WORK)
+- return tn;
++ return;
+
+ /* Halve as long as the number of empty children in this
+ * node is above threshold.
+ */
+ max_work = MAX_WORK;
+- while (should_halve(tn) && max_work--) {
+- old_tn = tn;
+- tn = halve(t, tn);
+- if (IS_ERR(tn)) {
+- tn = old_tn;
++ while (should_halve(tp, tn) && max_work--) {
++ if (halve(t, tn)) {
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+ this_cpu_inc(t->stats->resize_node_skipped);
+ #endif
+ break;
+ }
+- }
+
++ tn = rtnl_dereference(*cptr);
++ }
+
+ /* Only one child remains */
+ if (tn->empty_children == (tnode_child_length(tn) - 1)) {
+@@ -797,11 +794,12 @@ one_child:
+ n = tnode_get_child(tn, --i);
+ no_children:
+ /* compress one level */
+- node_set_parent(n, NULL);
++ put_child_root(tp, t, tn->key, n);
++ node_set_parent(n, tp);
++
++ /* drop dead node */
+ tnode_free_safe(tn);
+- return n;
+ }
+- return tn;
+ }
+
+ /* readside must use rcu_read_lock currently dump routines
+@@ -882,34 +880,19 @@ static struct tnode *fib_find_node(struc
+
+ static void trie_rebalance(struct trie *t, struct tnode *tn)
+ {
+- int wasfull;
+- t_key cindex, key;
+ struct tnode *tp;
+
+- key = tn->key;
+-
+- while (tn != NULL && (tp = node_parent(tn)) != NULL) {
+- cindex = get_index(key, tp);
+- wasfull = tnode_full(tp, tnode_get_child(tp, cindex));
+- tn = resize(t, tn);
+-
+- tnode_put_child_reorg(tp, cindex, tn, wasfull);
+-
+- tp = node_parent(tn);
+- if (!tp)
+- rcu_assign_pointer(t->trie, tn);
++ while ((tp = node_parent(tn)) != NULL) {
++ resize(t, tn);
+
+ tnode_free_flush();
+- if (!tp)
+- break;
+ tn = tp;
+ }
+
+ /* Handle last (top) tnode */
+ if (IS_TNODE(tn))
+- tn = resize(t, tn);
++ resize(t, tn);
+
+- rcu_assign_pointer(t->trie, tn);
+ tnode_free_flush();
+ }
+