From a721c3e54b80e45cd9202e7fca29ef018bed9069 Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Tue, 11 Apr 2023 21:01:55 +0300 Subject: [PATCH] net/sched: taprio: allow per-TC user input of FP adminStatus This is a duplication of the FP adminStatus logic introduced for tc-mqprio. Offloading is done through the tc_mqprio_qopt_offload structure embedded within tc_taprio_qopt_offload. So practically, if a device driver is written to treat the mqprio portion of taprio just like standalone mqprio, it gets unified handling of frame preemption. I would have reused more code with taprio, but this is mostly netlink attribute parsing, which is hard to transform into generic code without having something that stinks as a result. We have the same variables with the same semantics, just different nlattr type values (TCA_MQPRIO_TC_ENTRY=5 vs TCA_TAPRIO_ATTR_TC_ENTRY=12; TCA_MQPRIO_TC_ENTRY_FP=2 vs TCA_TAPRIO_TC_ENTRY_FP=3, etc) and consequently, different policies for the nest. Every time nla_parse_nested() is called, an on-stack table "tb" of nlattr pointers is allocated statically, up to the maximum understood nlattr type. That array size is hardcoded as a constant, but when transforming this into a common parsing function, it would become either a VLA (which the Linux kernel rightfully doesn't like) or a call to the allocator. Having FP adminStatus in tc-taprio can be seen as addressing the 802.1Q Annex S.3 "Scheduling and preemption used in combination, no HOLD/RELEASE" and S.4 "Scheduling and preemption used in combination with HOLD/RELEASE" use cases. HOLD and RELEASE events are emitted towards the underlying MAC Merge layer when the schedule hits a Set-And-Hold-MAC or a Set-And-Release-MAC gate operation. So within the tc-taprio UAPI space, one can distinguish between the 2 use cases by choosing whether to use the TC_TAPRIO_CMD_SET_AND_HOLD and TC_TAPRIO_CMD_SET_AND_RELEASE gate operations within the schedule, or just TC_TAPRIO_CMD_SET_GATES. A small part of the change is dedicated to refactoring the max_sdu nlattr parsing to put all logic under the "if" that tests for presence of that nlattr. Signed-off-by: Vladimir Oltean Reviewed-by: Ferenc Fejes Reviewed-by: Simon Horman Signed-off-by: Jakub Kicinski --- include/uapi/linux/pkt_sched.h | 1 + net/sched/sch_taprio.c | 65 +++++++++++++++++++++++++++++++++--------- 2 files changed, 53 insertions(+), 13 deletions(-) diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h index b8d29be..51a7add 100644 --- a/include/uapi/linux/pkt_sched.h +++ b/include/uapi/linux/pkt_sched.h @@ -1252,6 +1252,7 @@ enum { TCA_TAPRIO_TC_ENTRY_UNSPEC, TCA_TAPRIO_TC_ENTRY_INDEX, /* u32 */ TCA_TAPRIO_TC_ENTRY_MAX_SDU, /* u32 */ + TCA_TAPRIO_TC_ENTRY_FP, /* u32 */ /* add new constants above here */ __TCA_TAPRIO_TC_ENTRY_CNT, diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index cbad430..76db9a1 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -7,6 +7,7 @@ */ #include +#include #include #include #include @@ -96,6 +97,7 @@ struct taprio_sched { struct list_head taprio_list; int cur_txq[TC_MAX_QUEUE]; u32 max_sdu[TC_MAX_QUEUE]; /* save info from the user */ + u32 fp[TC_QOPT_MAX_QUEUE]; /* only for dump and offloading */ u32 txtime_delay; }; @@ -1002,6 +1004,9 @@ static const struct nla_policy entry_policy[TCA_TAPRIO_SCHED_ENTRY_MAX + 1] = { static const struct nla_policy taprio_tc_policy[TCA_TAPRIO_TC_ENTRY_MAX + 1] = { [TCA_TAPRIO_TC_ENTRY_INDEX] = { .type = NLA_U32 }, [TCA_TAPRIO_TC_ENTRY_MAX_SDU] = { .type = NLA_U32 }, + [TCA_TAPRIO_TC_ENTRY_FP] = NLA_POLICY_RANGE(NLA_U32, + TC_FP_EXPRESS, + TC_FP_PREEMPTIBLE), }; static const struct nla_policy taprio_policy[TCA_TAPRIO_ATTR_MAX + 1] = { @@ -1524,6 +1529,7 @@ static int taprio_enable_offload(struct net_device *dev, mqprio_qopt_reconstruct(dev, &offload->mqprio.qopt); offload->mqprio.extack = extack; taprio_sched_to_offload(dev, sched, offload, &caps); + mqprio_fp_to_offload(q->fp, &offload->mqprio); for (tc = 0; tc < TC_MAX_QUEUE; tc++) offload->max_sdu[tc] = q->max_sdu[tc]; @@ -1671,13 +1677,14 @@ out: static int taprio_parse_tc_entry(struct Qdisc *sch, struct nlattr *opt, u32 max_sdu[TC_QOPT_MAX_QUEUE], + u32 fp[TC_QOPT_MAX_QUEUE], unsigned long *seen_tcs, struct netlink_ext_ack *extack) { struct nlattr *tb[TCA_TAPRIO_TC_ENTRY_MAX + 1] = { }; struct net_device *dev = qdisc_dev(sch); - u32 val = 0; int err, tc; + u32 val; err = nla_parse_nested(tb, TCA_TAPRIO_TC_ENTRY_MAX, opt, taprio_tc_policy, extack); @@ -1702,15 +1709,18 @@ static int taprio_parse_tc_entry(struct Qdisc *sch, *seen_tcs |= BIT(tc); - if (tb[TCA_TAPRIO_TC_ENTRY_MAX_SDU]) + if (tb[TCA_TAPRIO_TC_ENTRY_MAX_SDU]) { val = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_MAX_SDU]); + if (val > dev->max_mtu) { + NL_SET_ERR_MSG_MOD(extack, "TC max SDU exceeds device max MTU"); + return -ERANGE; + } - if (val > dev->max_mtu) { - NL_SET_ERR_MSG_MOD(extack, "TC max SDU exceeds device max MTU"); - return -ERANGE; + max_sdu[tc] = val; } - max_sdu[tc] = val; + if (tb[TCA_TAPRIO_TC_ENTRY_FP]) + fp[tc] = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_FP]); return 0; } @@ -1720,29 +1730,51 @@ static int taprio_parse_tc_entries(struct Qdisc *sch, struct netlink_ext_ack *extack) { struct taprio_sched *q = qdisc_priv(sch); + struct net_device *dev = qdisc_dev(sch); u32 max_sdu[TC_QOPT_MAX_QUEUE]; + bool have_preemption = false; unsigned long seen_tcs = 0; + u32 fp[TC_QOPT_MAX_QUEUE]; struct nlattr *n; int tc, rem; int err = 0; - for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++) + for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++) { max_sdu[tc] = q->max_sdu[tc]; + fp[tc] = q->fp[tc]; + } nla_for_each_nested(n, opt, rem) { if (nla_type(n) != TCA_TAPRIO_ATTR_TC_ENTRY) continue; - err = taprio_parse_tc_entry(sch, n, max_sdu, &seen_tcs, + err = taprio_parse_tc_entry(sch, n, max_sdu, fp, &seen_tcs, extack); if (err) - goto out; + return err; } - for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++) + for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++) { q->max_sdu[tc] = max_sdu[tc]; + q->fp[tc] = fp[tc]; + if (fp[tc] != TC_FP_EXPRESS) + have_preemption = true; + } + + if (have_preemption) { + if (!FULL_OFFLOAD_IS_ENABLED(q->flags)) { + NL_SET_ERR_MSG(extack, + "Preemption only supported with full offload"); + return -EOPNOTSUPP; + } + + if (!ethtool_dev_mm_supported(dev)) { + NL_SET_ERR_MSG(extack, + "Device does not support preemption"); + return -EOPNOTSUPP; + } + } -out: return err; } @@ -2023,7 +2055,7 @@ static int taprio_init(struct Qdisc *sch, struct nlattr *opt, { struct taprio_sched *q = qdisc_priv(sch); struct net_device *dev = qdisc_dev(sch); - int i; + int i, tc; spin_lock_init(&q->current_entry_lock); @@ -2080,6 +2112,9 @@ static int taprio_init(struct Qdisc *sch, struct nlattr *opt, q->qdiscs[i] = qdisc; } + for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++) + q->fp[tc] = TC_FP_EXPRESS; + taprio_detect_broken_mqprio(q); return taprio_change(sch, opt, extack); @@ -2223,6 +2258,7 @@ error_nest: } static int taprio_dump_tc_entries(struct sk_buff *skb, + struct taprio_sched *q, struct sched_gate_list *sched) { struct nlattr *n; @@ -2240,6 +2276,9 @@ static int taprio_dump_tc_entries(struct sk_buff *skb, sched->max_sdu[tc])) goto nla_put_failure; + if (nla_put_u32(skb, TCA_TAPRIO_TC_ENTRY_FP, q->fp[tc])) + goto nla_put_failure; + nla_nest_end(skb, n); } @@ -2281,7 +2320,7 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb) nla_put_u32(skb, TCA_TAPRIO_ATTR_TXTIME_DELAY, q->txtime_delay)) goto options_error; - if (oper && taprio_dump_tc_entries(skb, oper)) + if (oper && taprio_dump_tc_entries(skb, q, oper)) goto options_error; if (oper && dump_schedule(skb, oper)) -- 2.7.4