net: fix length computation in rt_check_expire()

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>

1 files changed, 3 insertions, 2 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index c4c60e9f068a..869cf1c44b78 100644
--- 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)) {