net: sched: remove redundant NULL check in change hook function

Currently, the change function can be called by two ways. The one way is
that qdisc_change() will call it. Before calling change function,
qdisc_change() ensures tca[TCA_OPTIONS] is not empty. The other way is
that .init() will call it. The opt parameter is also checked before
calling change function in .init(). Therefore, it's no need to check the
input parameter opt in change function.

Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://lore.kernel.org/r/20220829071219.208646-1-shaozhengchao@huawei.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: zhengchaoshao

net/sched/sch_cake.c

@@ -2569,9 +2569,6 @@ static int cake_change(struct Qdisc *sch, struct nlattr *opt,
 	struct nlattr *tb[TCA_CAKE_MAX + 1];
 	int err;
 
-	if (!opt)
-		return -EINVAL;
-
 	err = nla_parse_nested_deprecated(tb, TCA_CAKE_MAX, opt, cake_policy,
 					  extack);
 	if (err < 0)

net/sched/sch_codel.c

@@ -138,9 +138,6 @@ static int codel_change(struct Qdisc *sch, struct nlattr *opt,
 	unsigned int qlen, dropped = 0;
 	int err;
 
-	if (!opt)
-		return -EINVAL;
-
 	err = nla_parse_nested_deprecated(tb, TCA_CODEL_MAX, opt,
 					  codel_policy, NULL);
 	if (err < 0)

net/sched/sch_ets.c

@@ -594,11 +594,6 @@ static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt,
 	unsigned int i;
 	int err;
 
-	if (!opt) {
-		NL_SET_ERR_MSG(extack, "ETS options are required for this operation");
-		return -EINVAL;
-	}
-
 	err = nla_parse_nested(tb, TCA_ETS_MAX, opt, ets_policy, extack);
 	if (err < 0)
 		return err;

net/sched/sch_fq.c

@@ -808,9 +808,6 @@ static int fq_change(struct Qdisc *sch, struct nlattr *opt,
 	unsigned drop_len = 0;
 	u32 fq_log;
 
-	if (!opt)
-		return -EINVAL;
-
 	err = nla_parse_nested_deprecated(tb, TCA_FQ_MAX, opt, fq_policy,
 					  NULL);
 	if (err < 0)

net/sched/sch_fq_codel.c

@@ -372,9 +372,6 @@ static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
 	u32 quantum = 0;
 	int err;
 
-	if (!opt)
-		return -EINVAL;
-
 	err = nla_parse_nested_deprecated(tb, TCA_FQ_CODEL_MAX, opt,
 					  fq_codel_policy, NULL);
 	if (err < 0)

net/sched/sch_fq_pie.c

@@ -283,9 +283,6 @@ static int fq_pie_change(struct Qdisc *sch, struct nlattr *opt,
 	unsigned int num_dropped = 0;
 	int err;
 
-	if (!opt)
-		return -EINVAL;
-
 	err = nla_parse_nested(tb, TCA_FQ_PIE_MAX, opt, fq_pie_policy, extack);
 	if (err < 0)
 		return err;

net/sched/sch_gred.c

@@ -648,9 +648,6 @@ static int gred_change(struct Qdisc *sch, struct nlattr *opt,
 	u32 max_P;
 	struct gred_sched_data *prealloc;
 
-	if (opt == NULL)
-		return -EINVAL;
-
 	err = nla_parse_nested_deprecated(tb, TCA_GRED_MAX, opt, gred_policy,
 					  extack);
 	if (err < 0)

net/sched/sch_hfsc.c

@@ -1430,7 +1430,7 @@ hfsc_change_qdisc(struct Qdisc *sch, struct nlattr *opt,
 	struct hfsc_sched *q = qdisc_priv(sch);
 	struct tc_hfsc_qopt *qopt;
 
-	if (opt == NULL || nla_len(opt) < sizeof(*qopt))
+	if (nla_len(opt) < sizeof(*qopt))
 		return -EINVAL;
 	qopt = nla_data(opt);
 

net/sched/sch_hhf.c

@@ -516,9 +516,6 @@ static int hhf_change(struct Qdisc *sch, struct nlattr *opt,
 	u32 new_quantum = q->quantum;
 	u32 new_hhf_non_hh_weight = q->hhf_non_hh_weight;
 
-	if (!opt)
-		return -EINVAL;
-
 	err = nla_parse_nested_deprecated(tb, TCA_HHF_MAX, opt, hhf_policy,
 					  NULL);
 	if (err < 0)

net/sched/sch_netem.c

@@ -961,9 +961,6 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt,
 	int old_loss_model = CLG_RANDOM;
 	int ret;
 
-	if (opt == NULL)
-		return -EINVAL;
-
 	qopt = nla_data(opt);
 	ret = parse_attr(tb, TCA_NETEM_MAX, opt, netem_policy, sizeof(*qopt));
 	if (ret < 0)