diff options
| author | Eric Dumazet <edumazet@google.com> | 2015-05-20 20:59:02 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-05-22 01:55:32 +0300 |
| commit | 946f9eb226c296da0d6c630bdad282ca11d77f60 (patch) | |
| tree | e57418581cf0adc129548c9427730f70b84045da | |
| parent | f5af1f57a2914e290de40e2c93716da8885c4965 (diff) | |
| download | linux-946f9eb226c296da0d6c630bdad282ca11d77f60.tar.xz | |
tcp: improve REUSEADDR/NOREUSEADDR cohabitation
inet_csk_get_port() randomization effort tends to spread
sockets on all the available range (ip_local_port_range)
This is unfortunate because SO_REUSEADDR sockets have
less requirements than non SO_REUSEADDR ones.
If an application uses SO_REUSEADDR hint, it is to try to
allow source ports being shared.
So instead of picking a random port number in ip_local_port_range,
lets try first in first half of the range.
This gives more chances to use upper half of the range for the
sockets with strong requirements (not using SO_REUSEADDR)
Note this patch does not add a new sysctl, and only changes
the way we try to pick port number.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Marcelo Ricardo Leitner <mleitner@redhat.com>
Cc: Flavio Leitner <fbl@redhat.com>
Acked-by: Flavio Leitner <fbl@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/inet_connection_sock.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index b95fb263a13f..60021d0d9326 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -99,6 +99,7 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum) struct net *net = sock_net(sk); int smallest_size = -1, smallest_rover; kuid_t uid = sock_i_uid(sk); + int attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0; local_bh_disable(); if (!snum) { @@ -106,6 +107,14 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum) again: inet_get_local_port_range(net, &low, &high); + if (attempt_half) { + int half = low + ((high - low) >> 1); + + if (attempt_half == 1) + high = half; + else + low = half; + } remaining = (high - low) + 1; smallest_rover = rover = prandom_u32() % remaining + low; @@ -154,6 +163,11 @@ again: snum = smallest_rover; goto have_snum; } + if (attempt_half == 1) { + /* OK we now try the upper half of the range */ + attempt_half = 2; + goto again; + } goto fail; } /* OK, here is the one we will use. HEAD is |