[PATCH v3 net-next 01/10] net/sched: taprio: don't access q->qdiscs[] in unoffloaded mode during attach()

Vladimir Oltean
2023-08-01T18:24:55Z

This is a simple code transformation with no intended behavior change,
just to make it absolutely clear that q->qdiscs[] is only attached to
the child taprio classes in full offload mode.

Right now we use the q->qdiscs[] variable in taprio_attach() for
software mode too, but that is quite confusing and avoidable. We use
it only to reach the netdev TX queue, but we could as well just use
netdev_get_tx_queue() for that.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
v1->v3: none

net/sched/sch_taprio.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 717ae51d94a0..d9ff75a08e12 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -2134,14 +2134,20 @@ static void taprio_attach(struct Qdisc *sch)

/* Attach underlying qdisc */
for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
- struct Qdisc *qdisc = q->qdiscs[ntx];
+ struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, ntx);
struct Qdisc *old;

if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {
+ struct Qdisc *qdisc = q->qdiscs[ntx];
+
qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
- old = dev_graft_qdisc(qdisc->dev_queue, qdisc);
+ old = dev_graft_qdisc(dev_queue, qdisc);
} else {
- old = dev_graft_qdisc(qdisc->dev_queue, sch);
+ /* In software mode, attach the root taprio qdisc
+ * to all netdev TX queues, so that dev_qdisc_enqueue()
+ * goes through taprio_enqueue().
+ */
+ old = dev_graft_qdisc(dev_queue, sch);
qdisc_refcount_inc(sch);
}
if (old)
--
2.34.1