[PATCH net-next v1] taprio: Fix using wrong queues in gate mask

[PATCH net-next v1] taprio: Fix using wrong queues in gate mask

[Vinicius Costa Gomes]

Since commit 9c66d1564676 ("taprio: Add support for hardware
offloading") there's a bit of inconsistency when offloading schedules
to the hardware:

In software mode, the gate masks are specified in terms of traffic
classes, so if say "sched-entry S 03 20000", it means that the traffic
classes 0 and 1 are open for 20us; when taprio is offloaded to
hardware, the gate masks are specified in terms of hardware queues.

The idea here is to fix hardware offloading, so schedules in hardware
and software mode have the same behavior. What's needed to do is to
map traffic classes to queues when applying the offload to the driver.

Fixes: 9c66d1564676 ("taprio: Add support for hardware offloading")
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
---
 net/sched/sch_taprio.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index e981992634dd..fe53c1e38c7d 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1176,9 +1176,27 @@ static void taprio_offload_config_changed(struct taprio_sched *q)
 	spin_unlock(&q->current_entry_lock);
 }
 
-static void taprio_sched_to_offload(struct taprio_sched *q,
+static u32 tc_map_to_queue_mask(struct net_device *dev, u32 tc_mask)
+{
+	u32 i, queue_mask = 0;
+
+	for (i = 0; i < dev->num_tc; i++) {
+		u32 offset, count;
+
+		if (!(tc_mask & BIT(i)))
+			continue;
+
+		offset = dev->tc_to_txq[i].offset;
+		count = dev->tc_to_txq[i].count;
+
+		queue_mask |= GENMASK(offset + count - 1, offset);
+	}
+
+	return queue_mask;
+}
+
+static void taprio_sched_to_offload(struct net_device *dev,
 				    struct sched_gate_list *sched,
-				    const struct tc_mqprio_qopt *mqprio,
 				    struct tc_taprio_qopt_offload *offload)
 {
 	struct sched_entry *entry;
@@ -1193,7 +1211,8 @@ static void taprio_sched_to_offload(struct taprio_sched *q,
 
 		e->command = entry->command;
 		e->interval = entry->interval;
-		e->gate_mask = entry->gate_mask;
+		e->gate_mask = tc_map_to_queue_mask(dev, entry->gate_mask);
+
 		i++;
 	}
 
@@ -1201,7 +1220,6 @@ static void taprio_sched_to_offload(struct taprio_sched *q,
 }
 
 static int taprio_enable_offload(struct net_device *dev,
-				 struct tc_mqprio_qopt *mqprio,
 				 struct taprio_sched *q,
 				 struct sched_gate_list *sched,
 				 struct netlink_ext_ack *extack)
@@ -1223,7 +1241,7 @@ static int taprio_enable_offload(struct net_device *dev,
 		return -ENOMEM;
 	}
 	offload->enable = 1;
-	taprio_sched_to_offload(q, sched, mqprio, offload);
+	taprio_sched_to_offload(dev, sched, offload);
 
 	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_TAPRIO, offload);
 	if (err < 0) {
@@ -1485,7 +1503,7 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt,
 	}
 
 	if (FULL_OFFLOAD_IS_ENABLED(q->flags))
-		err = taprio_enable_offload(dev, mqprio, q, new_admin, extack);
+		err = taprio_enable_offload(dev, q, new_admin, extack);
 	else
 		err = taprio_disable_offload(dev, q, extack);
 	if (err)
-- 
2.28.0

Re: [PATCH net-next v1] taprio: Fix using wrong queues in gate mask

[David Miller]

From: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Date: Tue, 25 Aug 2020 10:44:04 -0700

> Since commit 9c66d1564676 ("taprio: Add support for hardware
> offloading") there's a bit of inconsistency when offloading schedules
> to the hardware:
> 
> In software mode, the gate masks are specified in terms of traffic
> classes, so if say "sched-entry S 03 20000", it means that the traffic
> classes 0 and 1 are open for 20us; when taprio is offloaded to
> hardware, the gate masks are specified in terms of hardware queues.
> 
> The idea here is to fix hardware offloading, so schedules in hardware
> and software mode have the same behavior. What's needed to do is to
> map traffic classes to queues when applying the offload to the driver.
> 
> Fixes: 9c66d1564676 ("taprio: Add support for hardware offloading")
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>

As a bug fix I've applied this to 'net' and queued it up for -stable as
well, thank you.