[PATCH net-next 1/6] net: bridge: add a generic flush operation

[Nikolay Aleksandrov <razor@blackwall.org>]

Add a new bridge attribute (IFLA_BRIDGE_FLUSH) which will have embedded
attributes describing the object types that will be flushed. It will
allow fine-grained object flushing. Only a single flush attribute is
allowed per call since it can be a very load heavy operation. Also it is
allowed only with setlink command (similar to changelink flush). A nice
side-effect of using an af spec attribute is that it avoids making the
bridge link attribute options list longer.

An example structure for fdbs:
 [ IFLA_BRIDGE_FLUSH ]
  `[ BRIDGE_FDB_FLUSH ]
    `[ FDB_FLUSH_NDM_STATE ]
    `[ FDB_FLUSH_NDM_FLAGS ]

Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
---
 include/uapi/linux/if_bridge.h |  8 +++++++
 net/bridge/br_netlink.c        | 42 +++++++++++++++++++++++++++++++++-
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/if_bridge.h b/include/uapi/linux/if_bridge.h
index a86a7e7b811f..221a4256808f 100644
--- a/include/uapi/linux/if_bridge.h
+++ b/include/uapi/linux/if_bridge.h
@@ -123,6 +123,7 @@ enum {
 	IFLA_BRIDGE_MRP,
 	IFLA_BRIDGE_CFM,
 	IFLA_BRIDGE_MST,
+	IFLA_BRIDGE_FLUSH,
 	__IFLA_BRIDGE_MAX,
 };
 #define IFLA_BRIDGE_MAX (__IFLA_BRIDGE_MAX - 1)
@@ -802,4 +803,11 @@ enum {
 	__BRIDGE_QUERIER_MAX
 };
 #define BRIDGE_QUERIER_MAX (__BRIDGE_QUERIER_MAX - 1)
+
+/* embedded in IFLA_BRIDGE_FLUSH */
+enum {
+	BRIDGE_FLUSH_UNSPEC,
+	__BRIDGE_FLUSH_MAX
+};
+#define BRIDGE_FLUSH_MAX (__BRIDGE_FLUSH_MAX - 1)
 #endif /* _UAPI_LINUX_IF_BRIDGE_H */
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 200ad05b296f..fe2211d4c0c7 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -779,6 +779,34 @@ int br_process_vlan_info(struct net_bridge *br,
 	return err;
 }
 
+static const struct nla_policy br_flush_policy[BRIDGE_FLUSH_MAX + 1] = {
+	[BRIDGE_FLUSH_UNSPEC]	= { .type = NLA_REJECT },
+};
+
+static int br_flush(struct net_bridge *br, int cmd,
+		    struct nlattr *flush_attr,
+		    struct netlink_ext_ack *extack)
+{
+	struct nlattr *flush_tb[BRIDGE_FLUSH_MAX + 1];
+	int err;
+
+	switch (cmd) {
+	case RTM_SETLINK:
+		break;
+	default:
+		NL_SET_ERR_MSG_MOD(extack,
+				   "Bridge flush attribute is allowed only with RTM_SETLINK");
+		return -EINVAL;
+	}
+
+	err = nla_parse_nested(flush_tb, BRIDGE_FLUSH_MAX, flush_attr,
+			       br_flush_policy, extack);
+	if (err)
+		return err;
+
+	return 0;
+}
+
 static int br_afspec(struct net_bridge *br,
 		     struct net_bridge_port *p,
 		     struct nlattr *af_spec,
@@ -787,9 +815,10 @@ static int br_afspec(struct net_bridge *br,
 {
 	struct bridge_vlan_info *vinfo_curr = NULL;
 	struct bridge_vlan_info *vinfo_last = NULL;
-	struct nlattr *attr;
 	struct vtunnel_info tinfo_last = {};
 	struct vtunnel_info tinfo_curr = {};
+	bool flushed = false;
+	struct nlattr *attr;
 	int err = 0, rem;
 
 	nla_for_each_nested(attr, af_spec, rem) {
@@ -845,6 +874,17 @@ static int br_afspec(struct net_bridge *br,
 			if (err)
 				return err;
 			break;
+		case IFLA_BRIDGE_FLUSH:
+			if (flushed) {
+				NL_SET_ERR_MSG_MOD(extack,
+						   "Multiple bridge flush attributes are not allowed");
+				return -EINVAL;
+			}
+			err = br_flush(br, cmd, attr, extack);
+			if (err)
+				return err;
+			flushed = true;
+			break;
 		}
 	}
 
-- 
2.35.1