[PATCH net-next 1/6] flow_offload: add flow_rule_no_unsupp_control_flags()

["Asbjørn Sloth Tønnesen" <ast@fiberby.net>]

This helper can be used by drivers to check for the
presence of unsupported control flags.

It mirrors the existing check done in sfc:
  drivers/net/ethernet/sfc/tc.c +276

This is aimed at drivers, which implements some control flags.

This should also be used by drivers that implement all
current flags, so that future flags will be unsupported
by default.

Only compile-tested.

Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
---
 include/net/flow_offload.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/include/net/flow_offload.h b/include/net/flow_offload.h
index 314087a5e1818..c1317b14da08c 100644
--- a/include/net/flow_offload.h
+++ b/include/net/flow_offload.h
@@ -449,6 +449,28 @@ static inline bool flow_rule_match_key(const struct flow_rule *rule,
 	return dissector_uses_key(rule->match.dissector, key);
 }
 
+/**
+ * flow_rule_no_unsupp_control_flags() - check for unsupported control flags
+ * @supp_flags: flags supported by driver
+ * @flags: flags present in rule
+ * @extack: The netlink extended ACK for reporting errors.
+ *
+ * Returns true if only supported control flags are set, false otherwise.
+ */
+static inline bool flow_rule_no_unsupp_control_flags(const u32 supp_flags,
+						     const u32 flags,
+						     struct netlink_ext_ack *extack)
+{
+	if (likely((flags & ~supp_flags) == 0))
+		return true;
+
+	NL_SET_ERR_MSG_FMT_MOD(extack,
+			       "Unsupported match on control.flags %#x",
+			       flags);
+
+	return false;
+}
+
 struct flow_stats {
 	u64	pkts;
 	u64	bytes;
-- 
2.43.0