[PATCH net-next V2] net/dcb: Validate bandwidth for non-ETS traffic classes

[Tariq Toukan <tariqt@nvidia.com>]

From: Alexei Lazar <alazar@nvidia.com>

The IEEE 802.1Qaz standard defines that bandwidth allocation percentages
only apply to ETS traffic classes. Reject ETS configurations that
specify non-zero bandwidth for non-ETS traffic classes.

Placing this check in dcbnl_ieee_set() enforces the constraint uniformly
for all drivers rather than relying on each driver to validate it
independently.

Drop the equivalent check from NFP's dcb_ets_check(). Keep ETS
bandwidth-sum validation unchanged.

Signed-off-by: Alexei Lazar <alazar@nvidia.com>
Reviewed-by: Carolina Jubran <cjubran@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
 drivers/net/ethernet/netronome/nfp/nic/dcb.c | 3 ---
 net/dcb/dcbnl.c                              | 9 +++++++++
 2 files changed, 9 insertions(+), 3 deletions(-)

V2:
- Generalized per Jakub's suggestion.

V1:
https://lore.kernel.org/all/20260622112925.624795-3-tariqt@nvidia.com/

diff --git a/drivers/net/ethernet/netronome/nfp/nic/dcb.c b/drivers/net/ethernet/netronome/nfp/nic/dcb.c
index bb498ac6bd7d..91fbfa3708fc 100644
--- a/drivers/net/ethernet/netronome/nfp/nic/dcb.c
+++ b/drivers/net/ethernet/netronome/nfp/nic/dcb.c
@@ -218,9 +218,6 @@ static int dcb_ets_check(struct net_device *dev, struct ieee_ets *ets)
 		if (ets->tc_tsa[i] == IEEE_8021QAZ_TSA_ETS) {
 			ets_exists = true;
 			sum += ets->tc_tx_bw[i];
-		} else if (ets->tc_tx_bw[i]) {
-			nfp_warn(app->cpp, "ETS BW for strict/vendor TC must be 0.");
-			return -EINVAL;
 		}
 	}
 
diff --git a/net/dcb/dcbnl.c b/net/dcb/dcbnl.c
index 35164bfa563d..ab71f5312876 100644
--- a/net/dcb/dcbnl.c
+++ b/net/dcb/dcbnl.c
@@ -1578,6 +1578,15 @@ static int dcbnl_ieee_set(struct net_device *netdev, struct nlmsghdr *nlh,
 
 	if (ieee[DCB_ATTR_IEEE_ETS] && ops->ieee_setets) {
 		struct ieee_ets *ets = nla_data(ieee[DCB_ATTR_IEEE_ETS]);
+
+		/* IEEE 802.1Qaz: BW allocation applies only to ETS TCs */
+		for (int i = 0; i < IEEE_8021QAZ_MAX_TCS; i++) {
+			if (ets->tc_tsa[i] != IEEE_8021QAZ_TSA_ETS &&
+			    ets->tc_tx_bw[i]) {
+				err = -EINVAL;
+				goto err;
+			}
+		}
 		err = ops->ieee_setets(netdev, ets);
 		if (err)
 			goto err;

base-commit: d8674294aefef02266c4d47ad10131f1bffbe534
-- 
2.44.0