datapath: Make 100 percents packets sampled when sampling rate is 1.

When sampling rate is 1, the sampling probability is UINT32_MAX. The packet
should be sampled even the prandom32() generate the number of UINT32_MAX.
And none packet need be sampled when the probability is 0.

Signed-off-by: Wenyu Zhang <wenyuz@vmware.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Upstream: e05176a3283 ("openvswitch: Make 100 percents packets
sampled when sampling rate is 1.")

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>

diff --git a/datapath/actions.c b/datapath/actions.c
index 3ca45af..c529bbb 100644 (file)
--- a/datapath/actions.c
+++ b/datapath/actions.c
@@ -681,9 +681,12 @@ static int sample(struct datapath *dp, struct sk_buff *skb,
 
        for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
                 a = nla_next(a, &rem)) {
+               u32 probability;
+
                switch (nla_type(a)) {
                case OVS_SAMPLE_ATTR_PROBABILITY:
-                       if (prandom_u32() >= nla_get_u32(a))
+                       probability = nla_get_u32(a);
+                       if (!probability || prandom_u32() > probability)
                                return 0;
                        break;