linux: Report supported user features to the kernel

Following commit (''netlink: Do not enforce alignment of last Netlink
attribute''), signal the ability to receive unaligned Netlink messages
to the datapath to enable utilization of zerocopy optimizations.

Opening a datapath is now done by issueing a OVS_DP_CMD_SET in order
to overwrite previously set user features.

Signed-off-by: Thomas Graf <tgraf@redhat.com>
Acked-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>

diff --git a/lib/dpif-linux.c b/lib/dpif-linux.c
index f64e55b..482ba77 100644 (file)
--- a/lib/dpif-linux.c
+++ b/lib/dpif-linux.c
@@ -73,6 +73,7 @@ struct dpif_linux_dp {
     /* Attributes. */
     const char *name;                  /* OVS_DP_ATTR_NAME. */
     const uint32_t *upcall_pid;        /* OVS_DP_ATTR_UPCALL_PID. */
+    uint32_t user_features;            /* OVS_DP_ATTR_USER_FEATURES */
     struct ovs_dp_stats stats;         /* OVS_DP_ATTR_STATS. */
     struct ovs_dp_megaflow_stats megaflow_stats;
                                        /* OVS_DP_ATTR_MEGAFLOW_STATS.*/
@@ -231,9 +232,11 @@ dpif_linux_open(const struct dpif_class *class OVS_UNUSED, const char *name,
         upcall_pid = 0;
         dp_request.upcall_pid = &upcall_pid;
     } else {
-        dp_request.cmd = OVS_DP_CMD_GET;
+        /* Use OVS_DP_CMD_SET to report user features */
+        dp_request.cmd = OVS_DP_CMD_SET;
     }
     dp_request.name = name;
+    dp_request.user_features |= OVS_DP_F_UNALIGNED;
     error = dpif_linux_dp_transact(&dp_request, &dp, &buf);
     if (error) {
         return error;
@@ -1931,6 +1934,10 @@ dpif_linux_dp_to_ofpbuf(const struct dpif_linux_dp *dp, struct ofpbuf *buf)
         nl_msg_put_u32(buf, OVS_DP_ATTR_UPCALL_PID, *dp->upcall_pid);
     }
 
+    if (dp->user_features) {
+        nl_msg_put_u32(buf, OVS_DP_ATTR_USER_FEATURES, dp->user_features);
+    }
+
     /* Skip OVS_DP_ATTR_STATS since we never have a reason to serialize it. */
 }