Hi,
In the 2.6.11 code, I found this:
static int tcp_v6_get_port(struct sock *sk, unsigned short snum)
also in:
static int tcp_v4_get_port(struct sock *sk, unsigned short snum)
{
...
if (snum == 0) {
int low = sysctl_local_port_range[0];
int high = sysctl_local_port_range[1];
spin_lock(&tcp_portalloc_lock);
rover = tcp_port_rover;
do { rover++;
if ((rover < low) || (rover > high))
rover = low;
That 'rover < low' check is redundant?
ints are bigger then the maximum portnumber (65535) so when
rover++ gets too high, the check for 'rover > high' will truncate
it to low (in the next line) waaay before the int itself wraps.
It is needed because tcp_port_rover might be < low before the
function starts, in that case the check for <low can be taken out
of the loop.
Patch:
diff -uNr net/ipv4/tcp_ipv4.c.org net/ipv4/tcp_ipv4.c
--- net/ipv4/tcp_ipv4.c.org 2005-03-04 22:39:37.340950747 +0100
+++ net/ipv4/tcp_ipv4.c 2005-03-04 22:40:35.570059217 +0100
@@ -222,10 +222,13 @@
int rover;
spin_lock(&tcp_portalloc_lock);
- rover = tcp_port_rover;
+ if (tcp_port_rover < low)
+ rover = low;
+ else
+ rover = tcp_port_rover;
do {
rover++;
- if (rover < low || rover > high)
+ if (rover > high)
rover = low;
head = &tcp_bhash[tcp_bhashfn(rover)];
spin_lock(&head->lock);
diff -uNr net/ipv6/tcp_ipv6.c.org net/ipv6/tcp_ipv6.c
--- net/ipv6/tcp_ipv6.c.org 2005-03-04 22:41:44.043007791 +0100
+++ net/ipv6/tcp_ipv6.c 2005-03-04 22:42:17.604728073 +0100
@@ -139,9 +139,12 @@
int rover;
spin_lock(&tcp_portalloc_lock);
- rover = tcp_port_rover;
+ if (tcp_port_rover < low)
+ rover = low;
+ else
+ rover = tcp_port_rover;
do { rover++;
- if ((rover < low) || (rover > high))
+ if (rover > high)
rover = low;
head = &tcp_bhash[tcp_bhashfn(rover)];
spin_lock(&head->lock);
Signed-off-by: Folkert van Heusden <[email protected]>
Folkert van Heusden
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