[RFC net-next 1/8] pkt_cls: make tc_can_offload_extack() check chain index

[Jakub Kicinski <jakub.kicinski@netronome.com>]

No upstream drivers seem to allow offload of chains other than 0.
Save driver developers typing and make tc_can_offload_extack()
check for that condition as well.  Rename the function to
tc_can_offload_cls() to better represent its application.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
---
 drivers/net/ethernet/netronome/nfp/bpf/main.c |  4 +---
 drivers/net/netdevsim/bpf.c                   |  5 +----
 include/net/pkt_cls.h                         | 20 +++++++++++++-------
 3 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/bpf/main.c b/drivers/net/ethernet/netronome/nfp/bpf/main.c
index b3206855535a..552e2657b536 100644
--- a/drivers/net/ethernet/netronome/nfp/bpf/main.c
+++ b/drivers/net/ethernet/netronome/nfp/bpf/main.c
@@ -130,7 +130,7 @@ static int nfp_bpf_setup_tc_block_cb(enum tc_setup_type type,
 				   "only offload of BPF classifiers supported");
 		return -EOPNOTSUPP;
 	}
-	if (!tc_can_offload_extack(nn->dp.netdev, cls_bpf->common.extack))
+	if (!tc_can_offload_cls(nn->dp.netdev, &cls_bpf->common))
 		return -EOPNOTSUPP;
 	if (!nfp_net_ebpf_capable(nn)) {
 		NL_SET_ERR_MSG_MOD(cls_bpf->common.extack,
@@ -142,8 +142,6 @@ static int nfp_bpf_setup_tc_block_cb(enum tc_setup_type type,
 				   "only ETH_P_ALL supported as filter protocol");
 		return -EOPNOTSUPP;
 	}
-	if (cls_bpf->common.chain_index)
-		return -EOPNOTSUPP;
 
 	/* Only support TC direct action */
 	if (!cls_bpf->exts_integrated ||
diff --git a/drivers/net/netdevsim/bpf.c b/drivers/net/netdevsim/bpf.c
index 8166f121bbcc..bbcb8ec42208 100644
--- a/drivers/net/netdevsim/bpf.c
+++ b/drivers/net/netdevsim/bpf.c
@@ -135,7 +135,7 @@ int nsim_bpf_setup_tc_block_cb(enum tc_setup_type type,
 		return -EOPNOTSUPP;
 	}
 
-	if (!tc_can_offload_extack(ns->netdev, cls_bpf->common.extack))
+	if (!tc_can_offload_cls(ns->netdev, &cls_bpf->common))
 		return -EOPNOTSUPP;
 
 	if (cls_bpf->common.protocol != htons(ETH_P_ALL)) {
@@ -144,9 +144,6 @@ int nsim_bpf_setup_tc_block_cb(enum tc_setup_type type,
 		return -EOPNOTSUPP;
 	}
 
-	if (cls_bpf->common.chain_index)
-		return -EOPNOTSUPP;
-
 	if (!ns->bpf_tc_accept) {
 		NSIM_EA(cls_bpf->common.extack,
 			"netdevsim configured to reject BPF TC offload");
diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index 1a41513cec7f..84932226da67 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -645,15 +645,21 @@ static inline bool tc_can_offload(const struct net_device *dev)
 	return dev->features & NETIF_F_HW_TC;
 }
 
-static inline bool tc_can_offload_extack(const struct net_device *dev,
-					 struct netlink_ext_ack *extack)
+static inline bool tc_can_offload_cls(const struct net_device *dev,
+				      struct tc_cls_common_offload *common)
 {
-	bool can = tc_can_offload(dev);
-
-	if (!can)
-		NL_SET_ERR_MSG(extack, "TC offload is disabled on net device");
+	if (common->chain_index) {
+		NL_SET_ERR_MSG(common->extack,
+			       "Driver supports only offload of chain 0");
+		return false;
+	}
+	if (!tc_can_offload(dev)) {
+		NL_SET_ERR_MSG(common->extack,
+			       "TC offload is disabled on net device");
+		return false;
+	}
 
-	return can;
+	return true;
 }
 
 static inline bool tc_skip_hw(u32 flags)
-- 
2.15.1