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

[Greg KH]

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

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

From: Eric Dumazet <dada1@xxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxx>
Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 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)) {


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