netdev: Dynamic per-port Flow API.

Current issues with Flow API:

* OVS calls offloading functions regardless of successful
  flow API initialization. (ex. on init_flow_api failure)
* Static initilaization of Flow API for a netdev_class forbids
  having different offloading types for different instances
  of netdev with the same netdev_class. (ex. different vports in
  'system' and 'netdev' datapaths at the same time)

Solution:

* Move Flow API from the netdev_class to netdev instance.
* Make Flow API dynamic, i.e. probe the APIs and choose the
  suitable one.

Side effects:

* Flow API providers localized as possible in their modules.
* Now we have an ability to make runtime checks. For example,
  we could check if particular device supports features we
  need, like if dpdk device supports RSS+MARK action.

Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Acked-by: Roi Dayan <roid@mellanox.com>

lib/netdev-offload-provider.h

@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2009, 2010, 2011, 2012, 2013, 2014, 2016 Nicira, Inc.
+ * Copyright (c) 2019 Samsung Electronics Co.,Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef NETDEV_FLOW_API_PROVIDER_H
+#define NETDEV_FLOW_API_PROVIDER_H 1
+
+#include "flow.h"
+#include "openvswitch/types.h"
+#include "packets.h"
+
+#ifdef  __cplusplus
+extern "C" {
+#endif
+
+struct netdev_flow_api {
+    char *type;
+    /* Flush all offloaded flows from a netdev.
+     * Return 0 if successful, otherwise returns a positive errno value. */
+    int (*flow_flush)(struct netdev *);
+
+    /* Flow dumping interface.
+     *
+     * This is the back-end for the flow dumping interface described in
+     * dpif.h.  Please read the comments there first, because this code
+     * closely follows it.
+     *
+     * On success returns 0 and allocates data, on failure returns
+     * positive errno. */
+    int (*flow_dump_create)(struct netdev *, struct netdev_flow_dump **dump);
+    int (*flow_dump_destroy)(struct netdev_flow_dump *);
+
+    /* Returns true if there are more flows to dump.
+     * 'rbuffer' is used as a temporary buffer and needs to be pre allocated
+     * by the caller.  While there are more flows the same 'rbuffer'
+     * should be provided. 'wbuffer' is used to store dumped actions and needs
+     * to be pre allocated by the caller. */
+    bool (*flow_dump_next)(struct netdev_flow_dump *, struct match *,
+                           struct nlattr **actions,
+                           struct dpif_flow_stats *stats,
+                           struct dpif_flow_attrs *attrs, ovs_u128 *ufid,
+                           struct ofpbuf *rbuffer, struct ofpbuf *wbuffer);
+
+    /* Offload the given flow on netdev.
+     * To modify a flow, use the same ufid.
+     * 'actions' are in netlink format, as with struct dpif_flow_put.
+     * 'info' is extra info needed to offload the flow.
+     * 'stats' is populated according to the rules set out in the description
+     * above 'struct dpif_flow_put'.
+     * Return 0 if successful, otherwise returns a positive errno value. */
+    int (*flow_put)(struct netdev *, struct match *, struct nlattr *actions,
+                    size_t actions_len, const ovs_u128 *ufid,
+                    struct offload_info *info, struct dpif_flow_stats *);
+
+    /* Queries a flow specified by ufid on netdev.
+     * Fills output buffer as 'wbuffer' in flow_dump_next, which
+     * needs to be be pre allocated.
+     * Return 0 if successful, otherwise returns a positive errno value. */
+    int (*flow_get)(struct netdev *, struct match *, struct nlattr **actions,
+                    const ovs_u128 *ufid, struct dpif_flow_stats *,
+                    struct dpif_flow_attrs *, struct ofpbuf *wbuffer);
+
+    /* Delete a flow specified by ufid from netdev.
+     * 'stats' is populated according to the rules set out in the description
+     * above 'struct dpif_flow_del'.
+     * Return 0 if successful, otherwise returns a positive errno value. */
+    int (*flow_del)(struct netdev *, const ovs_u128 *ufid,
+                    struct dpif_flow_stats *);
+
+    /* Initializies the netdev flow api.
+     * Return 0 if successful, otherwise returns a positive errno value. */
+    int (*init_flow_api)(struct netdev *);
+};
+
+int netdev_register_flow_api_provider(const struct netdev_flow_api *);
+int netdev_unregister_flow_api_provider(const char *type);
+
+#ifdef __linux__
+extern const struct netdev_flow_api netdev_tc_offloads;
+#endif
+
+#ifdef  __cplusplus
+}
+#endif
+
+#endif /* NETDEV_FLOW_API_PROVIDER_H */