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Date: Tue, 19 Jun 2012 19:02:02 -0700 (PDT)
From: David Miller <davem@...emloft.net>
To: bhutchings@...arflare.com
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH v2] ipv4: Early TCP socket demux.
From: David Miller <davem@...emloft.net>
Date: Tue, 19 Jun 2012 18:05:27 -0700 (PDT)
> From: Ben Hutchings <bhutchings@...arflare.com>
> Date: Wed, 20 Jun 2012 02:03:26 +0100
>
>> On Tue, 2012-06-19 at 17:54 -0700, David Miller wrote:
>>> The hash is perfect, what's the big deal?
>>
>> It obscures what we're really doing and relying on.
>
> If it matters to you, patches are always welcome :-)
Nevermind, I just committed the following to net-next:
--------------------
inet: Sanitize inet{,6} protocol demux.
Don't pretend that inet_protos[] and inet6_protos[] are hashes, thay
are just a straight arrays. Remove all unnecessary hash masking.
Document MAX_INET_PROTOS.
Use RAW_HTABLE_SIZE when appropriate.
Reported-by: Ben Hutchings <bhutchings@...arflare.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
---
include/net/protocol.h | 7 +++++--
net/ipv4/af_inet.c | 26 ++++++++++++--------------
net/ipv4/icmp.c | 9 ++++-----
net/ipv4/ip_input.c | 5 ++---
net/ipv4/protocol.c | 8 +++-----
net/ipv6/icmp.c | 7 ++-----
net/ipv6/ip6_input.c | 9 +++------
net/ipv6/protocol.c | 8 +++-----
net/ipv6/raw.c | 4 ++--
9 files changed, 36 insertions(+), 47 deletions(-)
diff --git a/include/net/protocol.h b/include/net/protocol.h
index 875f489..a1b1b53 100644
--- a/include/net/protocol.h
+++ b/include/net/protocol.h
@@ -29,8 +29,11 @@
#include <linux/ipv6.h>
#endif
-#define MAX_INET_PROTOS 256 /* Must be a power of 2 */
-
+/* This is one larger than the largest protocol value that can be
+ * found in an ipv4 or ipv6 header. Since in both cases the protocol
+ * value is presented in a __u8, this is defined to be 256.
+ */
+#define MAX_INET_PROTOS 256
/* This is used to register protocols. */
struct net_protocol {
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index e4e8e00..85a3b17 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -242,20 +242,18 @@ void build_ehash_secret(void)
}
EXPORT_SYMBOL(build_ehash_secret);
-static inline int inet_netns_ok(struct net *net, int protocol)
+static inline int inet_netns_ok(struct net *net, __u8 protocol)
{
- int hash;
const struct net_protocol *ipprot;
if (net_eq(net, &init_net))
return 1;
- hash = protocol & (MAX_INET_PROTOS - 1);
- ipprot = rcu_dereference(inet_protos[hash]);
-
- if (ipprot == NULL)
+ ipprot = rcu_dereference(inet_protos[protocol]);
+ if (ipprot == NULL) {
/* raw IP is OK */
return 1;
+ }
return ipprot->netns_ok;
}
@@ -1216,8 +1214,8 @@ EXPORT_SYMBOL(inet_sk_rebuild_header);
static int inet_gso_send_check(struct sk_buff *skb)
{
- const struct iphdr *iph;
const struct net_protocol *ops;
+ const struct iphdr *iph;
int proto;
int ihl;
int err = -EINVAL;
@@ -1236,7 +1234,7 @@ static int inet_gso_send_check(struct sk_buff *skb)
__skb_pull(skb, ihl);
skb_reset_transport_header(skb);
iph = ip_hdr(skb);
- proto = iph->protocol & (MAX_INET_PROTOS - 1);
+ proto = iph->protocol;
err = -EPROTONOSUPPORT;
rcu_read_lock();
@@ -1253,8 +1251,8 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
struct sk_buff *segs = ERR_PTR(-EINVAL);
- struct iphdr *iph;
const struct net_protocol *ops;
+ struct iphdr *iph;
int proto;
int ihl;
int id;
@@ -1286,7 +1284,7 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
skb_reset_transport_header(skb);
iph = ip_hdr(skb);
id = ntohs(iph->id);
- proto = iph->protocol & (MAX_INET_PROTOS - 1);
+ proto = iph->protocol;
segs = ERR_PTR(-EPROTONOSUPPORT);
rcu_read_lock();
@@ -1340,7 +1338,7 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head,
goto out;
}
- proto = iph->protocol & (MAX_INET_PROTOS - 1);
+ proto = iph->protocol;
rcu_read_lock();
ops = rcu_dereference(inet_protos[proto]);
@@ -1398,11 +1396,11 @@ out:
static int inet_gro_complete(struct sk_buff *skb)
{
- const struct net_protocol *ops;
+ __be16 newlen = htons(skb->len - skb_network_offset(skb));
struct iphdr *iph = ip_hdr(skb);
- int proto = iph->protocol & (MAX_INET_PROTOS - 1);
+ const struct net_protocol *ops;
+ int proto = iph->protocol;
int err = -ENOSYS;
- __be16 newlen = htons(skb->len - skb_network_offset(skb));
csum_replace2(&iph->check, iph->tot_len, newlen);
iph->tot_len = newlen;
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index e1caa1a..49a74cc 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -637,12 +637,12 @@ EXPORT_SYMBOL(icmp_send);
static void icmp_unreach(struct sk_buff *skb)
{
+ const struct net_protocol *ipprot;
const struct iphdr *iph;
struct icmphdr *icmph;
- int hash, protocol;
- const struct net_protocol *ipprot;
- u32 info = 0;
struct net *net;
+ u32 info = 0;
+ int protocol;
net = dev_net(skb_dst(skb)->dev);
@@ -731,9 +731,8 @@ static void icmp_unreach(struct sk_buff *skb)
*/
raw_icmp_error(skb, protocol, info);
- hash = protocol & (MAX_INET_PROTOS - 1);
rcu_read_lock();
- ipprot = rcu_dereference(inet_protos[hash]);
+ ipprot = rcu_dereference(inet_protos[protocol]);
if (ipprot && ipprot->err_handler)
ipprot->err_handler(skb, info);
rcu_read_unlock();
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 8590144..c4fe1d2 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -198,14 +198,13 @@ static int ip_local_deliver_finish(struct sk_buff *skb)
rcu_read_lock();
{
int protocol = ip_hdr(skb)->protocol;
- int hash, raw;
const struct net_protocol *ipprot;
+ int raw;
resubmit:
raw = raw_local_deliver(skb, protocol);
- hash = protocol & (MAX_INET_PROTOS - 1);
- ipprot = rcu_dereference(inet_protos[hash]);
+ ipprot = rcu_dereference(inet_protos[protocol]);
if (ipprot != NULL) {
int ret;
diff --git a/net/ipv4/protocol.c b/net/ipv4/protocol.c
index 9ae5c01..8918eff 100644
--- a/net/ipv4/protocol.c
+++ b/net/ipv4/protocol.c
@@ -36,9 +36,7 @@ const struct net_protocol __rcu *inet_protos[MAX_INET_PROTOS] __read_mostly;
int inet_add_protocol(const struct net_protocol *prot, unsigned char protocol)
{
- int hash = protocol & (MAX_INET_PROTOS - 1);
-
- return !cmpxchg((const struct net_protocol **)&inet_protos[hash],
+ return !cmpxchg((const struct net_protocol **)&inet_protos[protocol],
NULL, prot) ? 0 : -1;
}
EXPORT_SYMBOL(inet_add_protocol);
@@ -49,9 +47,9 @@ EXPORT_SYMBOL(inet_add_protocol);
int inet_del_protocol(const struct net_protocol *prot, unsigned char protocol)
{
- int ret, hash = protocol & (MAX_INET_PROTOS - 1);
+ int ret;
- ret = (cmpxchg((const struct net_protocol **)&inet_protos[hash],
+ ret = (cmpxchg((const struct net_protocol **)&inet_protos[protocol],
prot, NULL) == prot) ? 0 : -1;
synchronize_net();
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 5247d5c..c7da142 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -600,9 +600,8 @@ static void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
{
const struct inet6_protocol *ipprot;
int inner_offset;
- int hash;
- u8 nexthdr;
__be16 frag_off;
+ u8 nexthdr;
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
return;
@@ -629,10 +628,8 @@ static void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
--ANK (980726)
*/
- hash = nexthdr & (MAX_INET_PROTOS - 1);
-
rcu_read_lock();
- ipprot = rcu_dereference(inet6_protos[hash]);
+ ipprot = rcu_dereference(inet6_protos[nexthdr]);
if (ipprot && ipprot->err_handler)
ipprot->err_handler(skb, NULL, type, code, inner_offset, info);
rcu_read_unlock();
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 21a15df..5ab923e 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -168,13 +168,12 @@ drop:
static int ip6_input_finish(struct sk_buff *skb)
{
+ struct net *net = dev_net(skb_dst(skb)->dev);
const struct inet6_protocol *ipprot;
+ struct inet6_dev *idev;
unsigned int nhoff;
int nexthdr;
bool raw;
- u8 hash;
- struct inet6_dev *idev;
- struct net *net = dev_net(skb_dst(skb)->dev);
/*
* Parse extension headers
@@ -189,9 +188,7 @@ resubmit:
nexthdr = skb_network_header(skb)[nhoff];
raw = raw6_local_deliver(skb, nexthdr);
-
- hash = nexthdr & (MAX_INET_PROTOS - 1);
- if ((ipprot = rcu_dereference(inet6_protos[hash])) != NULL) {
+ if ((ipprot = rcu_dereference(inet6_protos[nexthdr])) != NULL) {
int ret;
if (ipprot->flags & INET6_PROTO_FINAL) {
diff --git a/net/ipv6/protocol.c b/net/ipv6/protocol.c
index 9a7978f..053082d 100644
--- a/net/ipv6/protocol.c
+++ b/net/ipv6/protocol.c
@@ -29,9 +29,7 @@ const struct inet6_protocol __rcu *inet6_protos[MAX_INET_PROTOS] __read_mostly;
int inet6_add_protocol(const struct inet6_protocol *prot, unsigned char protocol)
{
- int hash = protocol & (MAX_INET_PROTOS - 1);
-
- return !cmpxchg((const struct inet6_protocol **)&inet6_protos[hash],
+ return !cmpxchg((const struct inet6_protocol **)&inet6_protos[protocol],
NULL, prot) ? 0 : -1;
}
EXPORT_SYMBOL(inet6_add_protocol);
@@ -42,9 +40,9 @@ EXPORT_SYMBOL(inet6_add_protocol);
int inet6_del_protocol(const struct inet6_protocol *prot, unsigned char protocol)
{
- int ret, hash = protocol & (MAX_INET_PROTOS - 1);
+ int ret;
- ret = (cmpxchg((const struct inet6_protocol **)&inet6_protos[hash],
+ ret = (cmpxchg((const struct inet6_protocol **)&inet6_protos[protocol],
prot, NULL) == prot) ? 0 : -1;
synchronize_net();
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 43b0042..b5c1dcb 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -165,7 +165,7 @@ static bool ipv6_raw_deliver(struct sk_buff *skb, int nexthdr)
saddr = &ipv6_hdr(skb)->saddr;
daddr = saddr + 1;
- hash = nexthdr & (MAX_INET_PROTOS - 1);
+ hash = nexthdr & (RAW_HTABLE_SIZE - 1);
read_lock(&raw_v6_hashinfo.lock);
sk = sk_head(&raw_v6_hashinfo.ht[hash]);
@@ -229,7 +229,7 @@ bool raw6_local_deliver(struct sk_buff *skb, int nexthdr)
{
struct sock *raw_sk;
- raw_sk = sk_head(&raw_v6_hashinfo.ht[nexthdr & (MAX_INET_PROTOS - 1)]);
+ raw_sk = sk_head(&raw_v6_hashinfo.ht[nexthdr & (RAW_HTABLE_SIZE - 1)]);
if (raw_sk && !ipv6_raw_deliver(skb, nexthdr))
raw_sk = NULL;
--
1.7.10
--
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