[PATCH net v2] openvswitch: meter: fix the incorrect calculation of max delta_t

[zhangliping]

From: zhangliping <zhanglipin...@baidu.com>

Max delat_t should be the full_bucket/rate instead of the full_bucket.
Also report EINVAL if the rate is zero.

Fixes: 96fbc13d7e77 ("openvswitch: Add meter infrastructure")
Cc: Andy Zhou <az...@ovn.org>
Signed-off-by: zhangliping <zhanglipin...@baidu.com>
---
 V2: report EINVAL if the rate is 0 to avoid divide by zero error.

 net/openvswitch/meter.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c
index 04b94281a30b..b891a91577f8 100644
--- a/net/openvswitch/meter.c
+++ b/net/openvswitch/meter.c
@@ -242,14 +242,20 @@ static struct dp_meter *dp_meter_create(struct nlattr **a)
 
                band->type = nla_get_u32(attr[OVS_BAND_ATTR_TYPE]);
                band->rate = nla_get_u32(attr[OVS_BAND_ATTR_RATE]);
+               if (band->rate == 0) {
+                       err = -EINVAL;
+                       goto exit_free_meter;
+               }
+
                band->burst_size = nla_get_u32(attr[OVS_BAND_ATTR_BURST]);
                /* Figure out max delta_t that is enough to fill any bucket.
                 * Keep max_delta_t size to the bucket units:
                 * pkts => 1/1000 packets, kilobits => bits.
+                *
+                * Start with a full bucket.
                 */
-               band_max_delta_t = (band->burst_size + band->rate) * 1000;
-               /* Start with a full bucket. */
-               band->bucket = band_max_delta_t;
+               band->bucket = (band->burst_size + band->rate) * 1000;
+               band_max_delta_t = band->bucket / band->rate;
                if (band_max_delta_t > meter->max_delta_t)
                        meter->max_delta_t = band_max_delta_t;
                band++;
-- 
2.13.4