diff options
| author | Tao Liu <thomas.liu@ucloud.cn> | 2021-05-13 21:08:00 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-05-13 15:54:59 -0700 |
| commit | e4df1b0c24350a0f00229ff895a91f1072bd850d (patch) | |
| tree | b9079a80dd57ca9bece8a015442dbc12d1c93864 /net/openvswitch | |
| parent | c7d8302478ae645c2e9b59f2cf125641875b7dc2 (diff) | |
openvswitch: meter: fix race when getting now_ms.
We have observed meters working unexpected if traffic is 3+Gbit/s
with multiple connections.
now_ms is not pretected by meter->lock, we may get a negative
long_delta_ms when another cpu updated meter->used, then:
delta_ms = (u32)long_delta_ms;
which will be a large value.
band->bucket += delta_ms * band->rate;
then we get a wrong band->bucket.
OpenVswitch userspace datapath has fixed the same issue[1] some
time ago, and we port the implementation to kernel datapath.
[1] https://patchwork.ozlabs.org/project/openvswitch/patch/20191025114436.9746-1-i.maximets@ovn.org/
Fixes: 96fbc13d7e77 ("openvswitch: Add meter infrastructure")
Signed-off-by: Tao Liu <thomas.liu@ucloud.cn>
Suggested-by: Ilya Maximets <i.maximets@ovn.org>
Reviewed-by: Ilya Maximets <i.maximets@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/openvswitch')
| -rw-r--r-- | net/openvswitch/meter.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c index 96b524ceabca..896b8f5bc885 100644 --- a/net/openvswitch/meter.c +++ b/net/openvswitch/meter.c @@ -611,6 +611,14 @@ bool ovs_meter_execute(struct datapath *dp, struct sk_buff *skb, spin_lock(&meter->lock); long_delta_ms = (now_ms - meter->used); /* ms */ + if (long_delta_ms < 0) { + /* This condition means that we have several threads fighting + * for a meter lock, and the one who received the packets a + * bit later wins. Assuming that all racing threads received + * packets at the same time to avoid overflow. + */ + long_delta_ms = 0; + } /* Make sure delta_ms will not be too large, so that bucket will not * wrap around below. |