Commit 3dd0c16e authored Apr 11, 2023 by Vladimir Oltean Committed by Jakub Kicinski Apr 13, 2023

net/sched: mqprio: simplify handling of nlattr portion of TCA_OPTIONS



In commit 4e8b86c0 ("mqprio: Introduce new hardware offload mode and
shaper in mqprio"), the TCA_OPTIONS format of mqprio was extended to
contain a fixed portion (of size NLA_ALIGN(sizeof struct tc_mqprio_qopt))
and a variable portion of other nlattrs (in the TCA_MQPRIO_* type space)
following immediately afterwards.

In commit feb2cf3d ("net/sched: mqprio: refactor nlattr parsing to a
separate function"), we've moved the nlattr handling to a smaller
function, but yet, a small parse_attr() still remains, and the larger
mqprio_parse_nlattr() still does not have access to the beginning, and
the length, of the TCA_OPTIONS region containing these other nlattrs.

In a future change, the mqprio qdisc will need to iterate through this
nlattr region to discover other attributes, so eliminate parse_attr()
and add 2 variables in mqprio_parse_nlattr() which hold the beginning
and the length of the nlattr range.

We avoid the need to memset when nlattr_opt_len has insufficient length
by pre-initializing the table "tb".

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Ferenc Fejes <fejes@inf.elte.hu>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent d54151aa

net/sched/sch_mqprio.c

+13 −19

Original line number	Diff line number	Diff line
		@@ -146,32 +146,26 @@ static const struct nla_policy mqprio_policy[TCA_MQPRIO_MAX + 1] = {
		[TCA_MQPRIO_MAX_RATE64] = { .type = NLA_NESTED },
		};

		static int parse_attr(struct nlattr tb[], int maxtype, struct nlattr nla,
		const struct nla_policy *policy, int len)
		{
		int nested_len = nla_len(nla) - NLA_ALIGN(len);

		if (nested_len >= nla_attr_size(0))
		return nla_parse_deprecated(tb, maxtype,
		nla_data(nla) + NLA_ALIGN(len),
		nested_len, policy, NULL);

		memset(tb, 0, sizeof(struct nlattr ) (maxtype + 1));
		return 0;
		}

		/* Parse the other netlink attributes that represent the payload of
		* TCA_OPTIONS, which are appended right after struct tc_mqprio_qopt.
		*/
		static int mqprio_parse_nlattr(struct Qdisc sch, struct tc_mqprio_qopt qopt,
		struct nlattr *opt)
		{
		struct nlattr nlattr_opt = nla_data(opt) + NLA_ALIGN(sizeof(qopt));
		int nlattr_opt_len = nla_len(opt) - NLA_ALIGN(sizeof(*qopt));
		struct mqprio_sched *priv = qdisc_priv(sch);
		struct nlattr *tb[TCA_MQPRIO_MAX + 1];
		struct nlattr *tb[TCA_MQPRIO_MAX + 1] = {};
		struct nlattr *attr;
		int i, rem, err;

		err = parse_attr(tb, TCA_MQPRIO_MAX, opt, mqprio_policy,
		sizeof(*qopt));
		if (nlattr_opt_len >= nla_attr_size(0)) {
		err = nla_parse_deprecated(tb, TCA_MQPRIO_MAX, nlattr_opt,
		nlattr_opt_len, mqprio_policy,
		NULL);
		if (err < 0)
		return err;
		}

		if (!qopt->hw)
		return -EINVAL;