Re: [PATCH] ipv6 route: Use flag instead of calling fib6_get_table() twice

[David Miller]

From: Masashi Honma 
Date: Sun, 25 Oct 2015 11:44:27 +0900

> The fib6_get_table() is called twice to show the warning.
> This patch reduces calling the function.
> 
> Signed-off-by: Masashi Honma 

I think the added cost of passing a reference to an on-stack variable
exceeds the value of whatever you think you are improving here.

The code as-is is fine as far as I'm concerned.
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[PATCH] ipv6 route: Use flag instead of calling fib6_get_table() twice

[Masashi Honma]

The fib6_get_table() is called twice to show the warning.
This patch reduces calling the function.

Signed-off-by: Masashi Honma 
---
 include/net/ip6_fib.h |  2 +-
 net/ipv6/fib6_rules.c |  3 ++-
 net/ipv6/ip6_fib.c| 10 +++---
 net/ipv6/route.c  | 13 -
 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index aaf9700..d6c5dff 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -256,7 +256,7 @@ typedef struct rt6_info *(*pol_lookup_t)(struct net *,
  */
 
 struct fib6_table *fib6_get_table(struct net *net, u32 id);
-struct fib6_table *fib6_new_table(struct net *net, u32 id);
+struct fib6_table *fib6_new_table(struct net *net, u32 id, int *exist);
 struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
   int flags, pol_lookup_t lookup);
 
diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index 9f777ec..7512941 100644
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -187,12 +187,13 @@ static int fib6_rule_configure(struct fib_rule *rule, 
struct sk_buff *skb,
int err = -EINVAL;
struct net *net = sock_net(skb->sk);
struct fib6_rule *rule6 = (struct fib6_rule *) rule;
+   int exist;
 
if (rule->action == FR_ACT_TO_TBL) {
if (rule->table == RT6_TABLE_UNSPEC)
goto errout;
 
-   if (fib6_new_table(net, rule->table) == NULL) {
+   if (fib6_new_table(net, rule->table, ) == NULL) {
err = -ENOBUFS;
goto errout;
}
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 7d2e002..abf65ef 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -226,16 +226,19 @@ static struct fib6_table *fib6_alloc_table(struct net 
*net, u32 id)
return table;
 }
 
-struct fib6_table *fib6_new_table(struct net *net, u32 id)
+struct fib6_table *fib6_new_table(struct net *net, u32 id, int *exist)
 {
struct fib6_table *tb;
 
if (id == 0)
id = RT6_TABLE_MAIN;
tb = fib6_get_table(net, id);
-   if (tb)
+   if (tb) {
+   *exist = 1;
return tb;
+   }
 
+   *exist = 0;
tb = fib6_alloc_table(net, id);
if (tb)
fib6_link_table(net, tb);
@@ -272,8 +275,9 @@ static void __net_init fib6_tables_init(struct net *net)
 }
 #else
 
-struct fib6_table *fib6_new_table(struct net *net, u32 id)
+struct fib6_table *fib6_new_table(struct net *net, u32 id, int *exist)
 {
+   *exist = 1;
return fib6_get_table(net, id);
 }
 
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index cb32ce2..7c4e0c2 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1757,6 +1757,7 @@ int ip6_route_info_create(struct fib6_config *cfg, struct 
rt6_info **rt_ret)
struct inet6_dev *idev = NULL;
struct fib6_table *table;
int addr_type;
+   int exist;
 
if (cfg->fc_dst_len > 128 || cfg->fc_src_len > 128)
return -EINVAL;
@@ -1778,16 +1779,10 @@ int ip6_route_info_create(struct fib6_config *cfg, 
struct rt6_info **rt_ret)
cfg->fc_metric = IP6_RT_PRIO_USER;
 
err = -ENOBUFS;
+   table = fib6_new_table(net, cfg->fc_table, );
if (cfg->fc_nlinfo.nlh &&
-   !(cfg->fc_nlinfo.nlh->nlmsg_flags & NLM_F_CREATE)) {
-   table = fib6_get_table(net, cfg->fc_table);
-   if (!table) {
-   pr_warn("NLM_F_CREATE should be specified when creating 
new route\n");
-   table = fib6_new_table(net, cfg->fc_table);
-   }
-   } else {
-   table = fib6_new_table(net, cfg->fc_table);
-   }
+   !(cfg->fc_nlinfo.nlh->nlmsg_flags & NLM_F_CREATE) && !exist)
+   pr_warn("NLM_F_CREATE should be specified when creating new 
route\n");
 
if (!table)
goto out;
-- 
1.9.1

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