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>
Change struct proto destroy function pointer to return void. Noticed
by Al Viro.
Signed-off-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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>
This patch causes UDP port allocation to be randomized like TCP.
The earlier code would always choose same port (ie first empty list).
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This reverts changesets:
6aaf47fa48b7b5f487abde34ed91c4fc038410b4
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>
__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>
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>
