[patch 06/87] net: fix length computation in rt_check_expire()

Greg KH
2009-06-09T10:16:43Z

[-- Attachment #1: net-fix-length-computation-in-rt_check_expire.patch --]
[-- Type: text/plain, Size: 1568 bytes --]

2.6.29-stable review patch. If anyone has any objections, please let us know.

------------------

From: Eric Dumazet <dada1@cosmosbay.com>

[ Upstream commit cf8da764fc6959b7efb482f375dfef9830e98205 ]

rt_check_expire() computes average and standard deviation of chain lengths,
but not correclty reset length to 0 at beginning of each chain.
This probably gives overflows for sum2 (and sum) on loaded machines instead
of meaningful results.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/ipv4/route.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -785,7 +785,7 @@ static void rt_check_expire(void)
static unsigned int rover;
unsigned int i = rover, goal;
struct rtable *rth, **rthp;
- unsigned long length = 0, samples = 0;
+ unsigned long samples = 0;
unsigned long sum = 0, sum2 = 0;
u64 mult;

@@ -795,9 +795,9 @@ static void rt_check_expire(void)
goal = (unsigned int)mult;
if (goal > rt_hash_mask)
goal = rt_hash_mask + 1;
- length = 0;
for (; goal > 0; goal--) {
unsigned long tmo = ip_rt_gc_timeout;
+ unsigned long length;

i = (i + 1) & rt_hash_mask;
rthp = &rt_hash_table[i].chain;
@@ -809,6 +809,7 @@ static void rt_check_expire(void)

if (*rthp == NULL)
continue;
+ length = 0;
spin_lock_bh(rt_hash_lock_addr(i));
while ((rth = *rthp) != NULL) {
if (rt_is_expired(rth)) {