[ovs-dev] [PATCH v2 08/22] datapath: Simplify labels length logic.

[Jarno Rajahalme]

Upstream commit:

    commit b87cec3814ccc7f6afb0a1378ee7e5110d07cdd3
    Author: Jarno Rajahalme <jarno at ovn.org>
    Date:   Thu Feb 9 11:21:56 2017 -0800

    openvswitch: Simplify labels length logic.

    Since 23014011ba42 ("netfilter: conntrack: support a fixed size of 128
    distinct labels"), the size of conntrack labels extension has fixed to
    128 bits, so we do not need to check for labels sizes shorter than 128
    at run-time.  This patch simplifies labels length logic accordingly,
    but allows the conntrack labels size to be increased in the future
    without breaking the build.  In the event of conntrack labels
    increasing in size OVS would still be able to deal with the 128 first
    label bits.

    Suggested-by: Joe Stringer <joe at ovn.org>
    Signed-off-by: Jarno Rajahalme <jarno at ovn.org>
    Acked-by: Pravin B Shelar <pshelar at ovn.org>
    Acked-by: Joe Stringer <joe at ovn.org>
    Signed-off-by: David S. Miller <davem at davemloft.net>

Signed-off-by: Jarno Rajahalme <jarno at ovn.org>
---
 datapath/conntrack.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/datapath/conntrack.c b/datapath/conntrack.c
index a827c6d..dacf34c 100644
--- a/datapath/conntrack.c
+++ b/datapath/conntrack.c
@@ -145,22 +145,20 @@ static size_t ovs_ct_get_labels_len(struct nf_conn_labels *cl)
 #endif
 }
 
+/* Guard against conntrack labels max size shrinking below 128 bits. */
+#if NF_CT_LABELS_MAX_SIZE < 16
+#error NF_CT_LABELS_MAX_SIZE must be at least 16 bytes
+#endif
+
 static void ovs_ct_get_labels(const struct nf_conn *ct,
 			      struct ovs_key_ct_labels *labels)
 {
 	struct nf_conn_labels *cl = ct ? nf_ct_labels_find(ct) : NULL;
 
-	if (cl) {
-		size_t len = ovs_ct_get_labels_len(cl);
-
-		if (len > OVS_CT_LABELS_LEN)
-			len = OVS_CT_LABELS_LEN;
-		else if (len < OVS_CT_LABELS_LEN)
-			memset(labels, 0, OVS_CT_LABELS_LEN);
-		memcpy(labels, cl->bits, len);
-	} else {
+	if (cl)
+		memcpy(labels, cl->bits, OVS_CT_LABELS_LEN);
+	else
 		memset(labels, 0, OVS_CT_LABELS_LEN);
-	}
 }
 
 static void __ovs_ct_update_key(struct sw_flow_key *key, u8 state,
-- 
2.1.4