[net PATCH] net/sched: Get stab before calling ops->change()
From: Xiaolei Wang
Date: Wed May 08 2024 - 22:42:13 EST
ops->change() depends on stab, there is such a situation
When no parameters are passed in for the first time, stab
is omitted, as in configuration 1 below. At this time, a
warning "Warning: sch_taprio: Size table not specified, frame
length estimates may be inaccurate" will be received. When
stab is added for the second time, parameters, like configuration
2 below, because the stab is still empty when ops->change()
is running, you will also receive the above warning.
1. tc qdisc replace dev eth1 parent root handle 100 taprio \
num_tc 5 map 0 1 2 3 4 queues 1@0 1@1 1@2 1@3 1@4 base-time 0 \
sched-entry S 1 100000 \
sched-entry S 2 100000 \
sched-entry S 4 100000 \
max-sdu 0 0 0 0 0 0 0 200 \
flags 2
2. tc qdisc replace dev eth1 parent root overhead 24 handle 100 taprio \
num_tc 5 map 0 1 2 3 4 queues 1@0 1@1 1@2 1@3 1@4 base-time 0 \
sched-entry S 1 100000 \
sched-entry S 2 100000 \
sched-entry S 4 100000 \
max-sdu 0 0 0 0 0 0 0 200 \
flags 2
Signed-off-by: Xiaolei Wang <xiaolei.wang@xxxxxxxxxxxxx>
---
net/sched/sch_api.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 60239378d43f..fec358f497d5 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1404,6 +1404,16 @@ static int qdisc_change(struct Qdisc *sch, struct nlattr **tca,
struct qdisc_size_table *ostab, *stab = NULL;
int err = 0;
+ if (tca[TCA_STAB]) {
+ stab = qdisc_get_stab(tca[TCA_STAB], extack);
+ if (IS_ERR(stab))
+ return PTR_ERR(stab);
+ }
+
+ ostab = rtnl_dereference(sch->stab);
+ rcu_assign_pointer(sch->stab, stab);
+ qdisc_put_stab(ostab);
+
if (tca[TCA_OPTIONS]) {
if (!sch->ops->change) {
NL_SET_ERR_MSG(extack, "Change operation not supported by specified qdisc");
@@ -1418,16 +1428,6 @@ static int qdisc_change(struct Qdisc *sch, struct nlattr **tca,
return err;
}
- if (tca[TCA_STAB]) {
- stab = qdisc_get_stab(tca[TCA_STAB], extack);
- if (IS_ERR(stab))
- return PTR_ERR(stab);
- }
-
- ostab = rtnl_dereference(sch->stab);
- rcu_assign_pointer(sch->stab, stab);
- qdisc_put_stab(ostab);
-
if (tca[TCA_RATE]) {
/* NB: ignores errors from replace_estimator
because change can't be undone. */
--
2.25.1