[PATCH net v2 3/6] igc: Handle already enabled taprio offload for basetime 0

From: Florian Kauer
Date: Mon Jun 19 2023 - 06:09:25 EST


Since commit e17090eb2494 ("igc: allow BaseTime 0 enrollment for Qbv")
it is possible to enable taprio offload with a basetime of 0.
However, the check if taprio offload is already enabled for i225
(and thus -EALREADY should be returned for igc_save_qbv_schedule)
still relied on adapter->base_time > 0.

This can be reproduced as follows:

# TAPRIO offload (flags == 0x2) and base-time = 0
sudo tc qdisc replace dev enp1s0 parent root handle 100 stab overhead 24 taprio \
num_tc 1 \
map 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 \
queues 1@0 \
base-time 0 \
sched-entry S 01 300000 \
flags 0x2

# The second call should fail with "Error: Device failed to setup taprio offload."
# But that only happens if base-time was != 0
sudo tc qdisc replace dev enp1s0 parent root handle 100 stab overhead 24 taprio \
num_tc 1 \
map 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 \
queues 1@0 \
base-time 0 \
sched-entry S 01 300000 \
flags 0x2

Fixes: e17090eb2494 ("igc: allow BaseTime 0 enrollment for Qbv")
Signed-off-by: Florian Kauer <florian.kauer@xxxxxxxxxxxxx>
Reviewed-by: Kurt Kanzenbach <kurt@xxxxxxxxxxxxx>
---
drivers/net/ethernet/intel/igc/igc_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 290daa5827f0..9c04df900b59 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -6082,7 +6082,7 @@ static int igc_save_qbv_schedule(struct igc_adapter *adapter,
if (qopt->base_time < 0)
return -ERANGE;

- if (igc_is_device_id_i225(hw) && adapter->base_time)
+ if (igc_is_device_id_i225(hw) && adapter->taprio_offload_enable)
return -EALREADY;

if (!validate_schedule(adapter, qopt))
--
2.39.2