Commit Graph

24 Commits

Author SHA1 Message Date
Eric Dumazet
271b72c7fa udp: RCU handling for Unicast packets.
Goals are :

1) Optimizing handling of incoming Unicast UDP frames, so that no memory
 writes should happen in the fast path.

 Note: Multicasts and broadcasts still will need to take a lock,
 because doing a full lockless lookup in this case is difficult.

2) No expensive operations in the socket bind/unhash phases :
  - No expensive synchronize_rcu() calls.

  - No added rcu_head in socket structure, increasing memory needs,
  but more important, forcing us to use call_rcu() calls,
  that have the bad property of making sockets structure cold.
  (rcu grace period between socket freeing and its potential reuse
   make this socket being cold in CPU cache).
  David did a previous patch using call_rcu() and noticed a 20%
  impact on TCP connection rates.
  Quoting Cristopher Lameter :
   "Right. That results in cacheline cooldown. You'd want to recycle
    the object as they are cache hot on a per cpu basis. That is screwed
    up by the delayed regular rcu processing. We have seen multiple
    regressions due to cacheline cooldown.
    The only choice in cacheline hot sensitive areas is to deal with the
    complexity that comes with SLAB_DESTROY_BY_RCU or give up on RCU."

  - Because udp sockets are allocated from dedicated kmem_cache,
  use of SLAB_DESTROY_BY_RCU can help here.

Theory of operation :
---------------------

As the lookup is lockfree (using rcu_read_lock()/rcu_read_unlock()),
special attention must be taken by readers and writers.

Use of SLAB_DESTROY_BY_RCU is tricky too, because a socket can be freed,
reused, inserted in a different chain or in worst case in the same chain
while readers could do lookups in the same time.

In order to avoid loops, a reader must check each socket found in a chain
really belongs to the chain the reader was traversing. If it finds a
mismatch, lookup must start again at the begining. This *restart* loop
is the reason we had to use rdlock for the multicast case, because
we dont want to send same message several times to the same socket.

We use RCU only for fast path.
Thus, /proc/net/udp still takes spinlocks.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-29 02:11:14 -07:00
Eric Dumazet
645ca708f9 udp: introduce struct udp_table and multiple spinlocks
UDP sockets are hashed in a 128 slots hash table.

This hash table is protected by *one* rwlock.

This rwlock is readlocked each time an incoming UDP message is handled.

This rwlock is writelocked each time a socket must be inserted in
hash table (bind time), or deleted from this table (close time)

This is not scalable on SMP machines :

1) Even in read mode, lock() and unlock() are atomic operations and
 must dirty a contended cache line, shared by all cpus.

2) A writer might be starved if many readers are 'in flight'. This can
 happen on a machine with some NIC receiving many UDP messages. User
 process can be delayed a long time at socket creation/dismantle time.

This patch prepares RCU migration, by introducing 'struct udp_table
and struct udp_hslot', and using one spinlock per chain, to reduce
contention on central rwlock.

Introducing one spinlock per chain reduces latencies, for port
randomization on heavily loaded UDP servers. This also speedup
bindings to specific ports.

udp_lib_unhash() was uninlined, becoming to big.

Some cleanups were done to ease review of following patch
(RCUification of UDP Unicast lookups)

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-29 01:41:45 -07:00
Denis V. Lunev
be713a443e netns: make uplitev6 mib per/namespace
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-07 14:50:06 -07:00
Adrian Bunk
0b04082995 net: remove CVS keywords
This patch removes CVS keywords that weren't updated for a long time
from comments.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-06-11 21:00:38 -07:00
Denis V. Lunev
4ad96d39a2 [UDP]: Remove owner from udp_seq_afinfo.
Move it to udp_seq_afinfo->seq_fops as should be.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-28 18:25:53 -07:00
Denis V. Lunev
3ba9441bdf [UDP]: Place file operations directly into udp_seq_afinfo.
No need to have separate never-used variable.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-28 18:25:32 -07:00
Denis V. Lunev
dda61925f8 [UDP]: Move seq_ops from udp_iter_state to udp_seq_afinfo.
No need to create seq_operations for each instance of 'netstat'.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-28 18:24:26 -07:00
Pavel Emelyanov
bdcde3d71a [SOCK]: Drop inuse pcounter from struct proto (v2).
An uppercut - do not use the pcounter on struct proto.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-28 16:39:33 -07:00
Pavel Emelyanov
84c375af0f [NETNS][UDP-Lite]: Register /proc/net/udplite(6) in a namespace.
UDP-Lite sockets are displayed in another files, rather than
UDP ones, so make the present in namespaces as well.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-24 14:56:57 -07:00
Pavel Emelyanov
6ba5a3c52d [UDP]: Make full use of proto.h.udp_hash innovation.
After this we have only udp_lib_get_port to get the port and two 
stubs for ipv4 and ipv6. No difference in udp and udplite except
for initialized h.udp_hash member.

I tried to find a graceful way to drop the only difference between
udp_v4_get_port and udp_v6_get_port (i.e. the rcv_saddr comparison 
routine), but adding one more callback on the struct proto didn't 
appear such :( Maybe later.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-22 16:51:21 -07:00
Daniel Lezcano
0c96d8c50b [NETNS][IPV6] udp6 - make proc per namespace
The proc init/exit functions take a new network namespace parameter in
order to register/unregister /proc/net/udp6 for a namespace.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-21 04:14:17 -07:00
David S. Miller
db8dac20d5 [UDP]: Revert udplite and code split.
This reverts commit db1ed684f6 ("[IPV6]
UDP: Rename IPv6 UDP files."), commit
8be8af8fa4 ("[IPV4] UDP: Move
IPv4-specific bits to other file.") and commit
e898d4db27 ("[UDP]: Allow users to
configure UDP-Lite.").

First, udplite is of such small cost, and it is a core protocol just
like TCP and normal UDP are.

We spent enormous amounts of effort to make udplite share as much code
with core UDP as possible.  All of that work is less valuable if we're
just going to slap a config option on udplite support.

It is also causing build failures, as reported on linux-next, showing
that the changeset was not tested very well.  In fact, this is the
second build failure resulting from the udplite change.

Finally, the config options provided was a bool, instead of a modular
option.  Meaning the udplite code does not even get build tested
by allmodconfig builds, and furthermore the user is not presented
with a reasonable modular build option which is particularly needed
by distribution vendors.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-03-06 16:22:02 -08:00
YOSHIFUJI Hideaki
db1ed684f6 [IPV6] UDP: Rename IPv6 UDP files.
Rename net/ipv6/udp.c to net/ipv6/udp_ipv6.c
Rename net/ipv6/udplite.c to net/ipv6/udplite_ipv6.c.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2008-03-04 15:18:22 +09:00
YOSHIFUJI Hideaki
77d0d350e9 [IPV6] UDP,UDPLITE: Sparse: {__udp6_lib,udp,udplite}_err() are of void.
Fix following sparse warnings:
| net/ipv6/udp.c:262:2: warning: returning void-valued expression
| net/ipv6/udplite.c:29:2: warning: returning void-valued expression

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2008-01-28 15:10:25 -08:00
Daniel Lezcano
09f7709f49 [IPV6]: fix section mismatch warnings
Removed useless and buggy __exit section in the different
ipv6 subsystems. Otherwise they will be called inside an
init section during rollbacking in case of an error in the
protocol initialization.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:57:46 -08:00
Daniel Lezcano
7f4e4868f3 [IPV6]: make the protocol initialization to return an error code
This patchset makes the different protocols to return an error code, so
the af_inet6 module can check the initialization was correct or not.

The raw6 was taken into account to be consistent with the rest of the
protocols, but the registration is at the same place.
Because the raw6 has its own init function, the proto and the ops structure
can be moved inside the raw6.c file.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:57:13 -08:00
Eric Dumazet
c5a432f1a1 [IPV6]: Use the {DEFINE|REF}_PROTO_INUSE infrastructure
Trivial patch to make "tcpv6,udpv6,udplitev6,rawv6" protocols uses the
fast "inuse sockets" infrastructure

Each protocol use then a static percpu var, instead of a dynamic one.
This saves some ram and some cpu cycles

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-11-07 04:08:59 -08:00
Herbert Xu
e5bbef20e0 [IPV6]: Replace sk_buff ** with sk_buff * in input handlers
With all the users of the double pointers removed from the IPv6 input path,
this patch converts all occurances of sk_buff ** to sk_buff * in IPv6 input
handlers.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-15 12:50:28 -07:00
David S. Miller
df2bc459a3 [UDP]: Revert 2-pass hashing changes.
This reverts changesets:

6aaf47fa48
b7b5f487ab
de34ed91c4
fc038410b4

There are still some correctness issues recently
discovered which do not have a known fix that doesn't
involve doing a full hash table scan on port bind.

So revert for now.

Signed-off-by: David S. Miller <davem@davemloft.net>
2007-06-07 13:40:50 -07:00
David S. Miller
fc038410b4 [UDP]: Fix AF-specific references in AF-agnostic code.
__udp_lib_port_inuse() cannot make direct references to
inet_sk(sk)->rcv_saddr as that is ipv4 specific state and
this code is used by ipv6 too.

Use an operations vector to solve this, and this also paves
the way for ipv6 support for non-wild saddr hashing in UDP.

Signed-off-by: David S. Miller <davem@davemloft.net>
2007-05-10 23:47:22 -07:00
Herbert Xu
759e5d0064 [UDP]: Clean up UDP-Lite receive checksum
This patch eliminates some duplicate code for the verification of
receive checksums between UDP-Lite and UDP.  It does this by
introducing __skb_checksum_complete_head which is identical to
__skb_checksum_complete_head apart from the fact that it takes
a length parameter rather than computing the first skb->len bytes.

As a result UDP-Lite will be able to use hardware checksum offload
for packets which do not use partial coverage checksums.  It also
means that UDP-Lite loopback no longer does unnecessary checksum
verification.

If any NICs start support UDP-Lite this would also start working
automatically.

This patch removes the assumption that msg_flags has MSG_TRUNC clear
upon entry in recvmsg.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25 22:23:51 -07:00
Adrian Bunk
f5b99bcddd [NET]: Possible cleanups.
This patch contains the following possible cleanups:
- make the following needlessly global functions statis:
  - ipv4/tcp.c: __tcp_alloc_md5sig_pool()
  - ipv4/tcp_ipv4.c: tcp_v4_reqsk_md5_lookup()
  - ipv4/udplite.c: udplite_rcv()
  - ipv4/udplite.c: udplite_err()
- make the following needlessly global structs static:
  - ipv4/tcp_ipv4.c: tcp_request_sock_ipv4_ops
  - ipv4/tcp_ipv4.c: tcp_sock_ipv4_specific
  - ipv6/tcp_ipv6.c: tcp_request_sock_ipv6_ops
- net/ipv{4,6}/udplite.c: remove inline's from static functions
                          (gcc should know best when to inline them)

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 21:31:51 -08:00
Al Viro
8e5200f540 [NET]: Fix assorted misannotations (from md5 and udplite merges).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 21:27:16 -08:00
Gerrit Renker
ba4e58eca8 [NET]: Supporting UDP-Lite (RFC 3828) in Linux
This is a revision of the previously submitted patch, which alters
the way files are organized and compiled in the following manner:

	* UDP and UDP-Lite now use separate object files
	* source file dependencies resolved via header files
	  net/ipv{4,6}/udp_impl.h
	* order of inclusion files in udp.c/udplite.c adapted
	  accordingly

[NET/IPv4]: Support for the UDP-Lite protocol (RFC 3828)

This patch adds support for UDP-Lite to the IPv4 stack, provided as an
extension to the existing UDPv4 code:
        * generic routines are all located in net/ipv4/udp.c
        * UDP-Lite specific routines are in net/ipv4/udplite.c
        * MIB/statistics support in /proc/net/snmp and /proc/net/udplite
        * shared API with extensions for partial checksum coverage

[NET/IPv6]: Extension for UDP-Lite over IPv6

It extends the existing UDPv6 code base with support for UDP-Lite
in the same manner as per UDPv4. In particular,
        * UDPv6 generic and shared code is in net/ipv6/udp.c
        * UDP-Litev6 specific extensions are in net/ipv6/udplite.c
        * MIB/statistics support in /proc/net/snmp6 and /proc/net/udplite6
        * support for IPV6_ADDRFORM
        * aligned the coding style of protocol initialisation with af_inet6.c
        * made the error handling in udpv6_queue_rcv_skb consistent;
          to return `-1' on error on all error cases
        * consolidation of shared code

[NET]: UDP-Lite Documentation and basic XFRM/Netfilter support

The UDP-Lite patch further provides
        * API documentation for UDP-Lite
        * basic xfrm support
        * basic netfilter support for IPv4 and IPv6 (LOG target)

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 21:22:46 -08:00