kernel: backport fib_trie improvements/fixes from 4.0-rc

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 44695

1 files changed, 200 insertions, 0 deletions

diff --git a/target/linux/generic/patches-3.18/080-02-fib_trie-Update-usage-stats-to-be-percpu-instead-of-.patch b/target/linux/generic/patches-3.18/080-02-fib_trie-Update-usage-stats-to-be-percpu-instead-of-.patch
new file mode 100644
index 0000000..8384009
--- /dev/null
+++ b/target/linux/generic/patches-3.18/080-02-fib_trie-Update-usage-stats-to-be-percpu-instead-of-.patch
@@ -0,0 +1,200 @@
+From: Alexander Duyck <alexander.h.duyck@redhat.com>
+Date: Wed, 31 Dec 2014 10:55:29 -0800
+Subject: [PATCH] fib_trie: Update usage stats to be percpu instead of
+ global variables
+
+The trie usage stats were currently being shared by all threads that were
+calling fib_table_lookup.  As a result when multiple threads were
+performing lookups simultaneously the trie would begin to cache bounce
+between those threads.
+
+In order to prevent this I have updated the usage stats to use a set of
+percpu variables.  By doing this we should be able to avoid the cache
+bouncing and still make use of these stats.
+
+Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+
+--- a/net/ipv4/fib_frontend.c
++++ b/net/ipv4/fib_frontend.c
+@@ -67,7 +67,7 @@ static int __net_init fib4_rules_init(st
+ 	return 0;
+ 
+ fail:
+-	kfree(local_table);
++	fib_free_table(local_table);
+ 	return -ENOMEM;
+ }
+ #else
+--- a/net/ipv4/fib_trie.c
++++ b/net/ipv4/fib_trie.c
+@@ -153,7 +153,7 @@ struct trie_stat {
+ struct trie {
+ 	struct rt_trie_node __rcu *trie;
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+-	struct trie_use_stats stats;
++	struct trie_use_stats __percpu *stats;
+ #endif
+ };
+ 
+@@ -631,7 +631,7 @@ static struct rt_trie_node *resize(struc
+ 		if (IS_ERR(tn)) {
+ 			tn = old_tn;
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+-			t->stats.resize_node_skipped++;
++			this_cpu_inc(t->stats->resize_node_skipped);
+ #endif
+ 			break;
+ 		}
+@@ -658,7 +658,7 @@ static struct rt_trie_node *resize(struc
+ 		if (IS_ERR(tn)) {
+ 			tn = old_tn;
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+-			t->stats.resize_node_skipped++;
++			this_cpu_inc(t->stats->resize_node_skipped);
+ #endif
+ 			break;
+ 		}
+@@ -1357,7 +1357,7 @@ static int check_leaf(struct fib_table *
+ 			err = fib_props[fa->fa_type].error;
+ 			if (err) {
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+-				t->stats.semantic_match_passed++;
++				this_cpu_inc(t->stats->semantic_match_passed);
+ #endif
+ 				return err;
+ 			}
+@@ -1372,7 +1372,7 @@ static int check_leaf(struct fib_table *
+ 					continue;
+ 
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+-				t->stats.semantic_match_passed++;
++				this_cpu_inc(t->stats->semantic_match_passed);
+ #endif
+ 				res->prefixlen = li->plen;
+ 				res->nh_sel = nhsel;
+@@ -1388,7 +1388,7 @@ static int check_leaf(struct fib_table *
+ 		}
+ 
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+-		t->stats.semantic_match_miss++;
++		this_cpu_inc(t->stats->semantic_match_miss);
+ #endif
+ 	}
+ 
+@@ -1399,6 +1399,9 @@ int fib_table_lookup(struct fib_table *t
+ 		     struct fib_result *res, int fib_flags)
+ {
+ 	struct trie *t = (struct trie *) tb->tb_data;
++#ifdef CONFIG_IP_FIB_TRIE_STATS
++	struct trie_use_stats __percpu *stats = t->stats;
++#endif
+ 	int ret;
+ 	struct rt_trie_node *n;
+ 	struct tnode *pn;
+@@ -1417,7 +1420,7 @@ int fib_table_lookup(struct fib_table *t
+ 		goto failed;
+ 
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+-	t->stats.gets++;
++	this_cpu_inc(stats->gets);
+ #endif
+ 
+ 	/* Just a leaf? */
+@@ -1441,7 +1444,7 @@ int fib_table_lookup(struct fib_table *t
+ 
+ 		if (n == NULL) {
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+-			t->stats.null_node_hit++;
++			this_cpu_inc(stats->null_node_hit);
+ #endif
+ 			goto backtrace;
+ 		}
+@@ -1576,7 +1579,7 @@ backtrace:
+ 			chopped_off = 0;
+ 
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+-			t->stats.backtrack++;
++			this_cpu_inc(stats->backtrack);
+ #endif
+ 			goto backtrace;
+ 		}
+@@ -1830,6 +1833,11 @@ int fib_table_flush(struct fib_table *tb
+ 
+ void fib_free_table(struct fib_table *tb)
+ {
++#ifdef CONFIG_IP_FIB_TRIE_STATS
++	struct trie *t = (struct trie *)tb->tb_data;
++
++	free_percpu(t->stats);
++#endif /* CONFIG_IP_FIB_TRIE_STATS */
+ 	kfree(tb);
+ }
+ 
+@@ -1973,7 +1981,14 @@ struct fib_table *fib_trie_table(u32 id)
+ 	tb->tb_num_default = 0;
+ 
+ 	t = (struct trie *) tb->tb_data;
+-	memset(t, 0, sizeof(*t));
++	RCU_INIT_POINTER(t->trie, NULL);
++#ifdef CONFIG_IP_FIB_TRIE_STATS
++	t->stats = alloc_percpu(struct trie_use_stats);
++	if (!t->stats) {
++		kfree(tb);
++		tb = NULL;
++	}
++#endif
+ 
+ 	return tb;
+ }
+@@ -2139,18 +2154,31 @@ static void trie_show_stats(struct seq_f
+ 
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+ static void trie_show_usage(struct seq_file *seq,
+-			    const struct trie_use_stats *stats)
++			    const struct trie_use_stats __percpu *stats)
+ {
++	struct trie_use_stats s = { 0 };
++	int cpu;
++
++	/* loop through all of the CPUs and gather up the stats */
++	for_each_possible_cpu(cpu) {
++		const struct trie_use_stats *pcpu = per_cpu_ptr(stats, cpu);
++
++		s.gets += pcpu->gets;
++		s.backtrack += pcpu->backtrack;
++		s.semantic_match_passed += pcpu->semantic_match_passed;
++		s.semantic_match_miss += pcpu->semantic_match_miss;
++		s.null_node_hit += pcpu->null_node_hit;
++		s.resize_node_skipped += pcpu->resize_node_skipped;
++	}
++
+ 	seq_printf(seq, "\nCounters:\n---------\n");
+-	seq_printf(seq, "gets = %u\n", stats->gets);
+-	seq_printf(seq, "backtracks = %u\n", stats->backtrack);
++	seq_printf(seq, "gets = %u\n", s.gets);
++	seq_printf(seq, "backtracks = %u\n", s.backtrack);
+ 	seq_printf(seq, "semantic match passed = %u\n",
+-		   stats->semantic_match_passed);
+-	seq_printf(seq, "semantic match miss = %u\n",
+-		   stats->semantic_match_miss);
+-	seq_printf(seq, "null node hit= %u\n", stats->null_node_hit);
+-	seq_printf(seq, "skipped node resize = %u\n\n",
+-		   stats->resize_node_skipped);
++		   s.semantic_match_passed);
++	seq_printf(seq, "semantic match miss = %u\n", s.semantic_match_miss);
++	seq_printf(seq, "null node hit= %u\n", s.null_node_hit);
++	seq_printf(seq, "skipped node resize = %u\n\n", s.resize_node_skipped);
+ }
+ #endif /*  CONFIG_IP_FIB_TRIE_STATS */
+ 
+@@ -2191,7 +2219,7 @@ static int fib_triestat_seq_show(struct 
+ 			trie_collect_stats(t, &stat);
+ 			trie_show_stats(seq, &stat);
+ #ifdef CONFIG_IP_FIB_TRIE_STATS
+-			trie_show_usage(seq, &t->stats);
++			trie_show_usage(seq, t->stats);
+ #endif
+ 		}
+ 	}