From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- net/sched/sch_codel.c | 324 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 324 insertions(+) create mode 100644 net/sched/sch_codel.c (limited to 'net/sched/sch_codel.c') diff --git a/net/sched/sch_codel.c b/net/sched/sch_codel.c new file mode 100644 index 000000000..cacf52449 --- /dev/null +++ b/net/sched/sch_codel.c @@ -0,0 +1,324 @@ +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause +/* + * Codel - The Controlled-Delay Active Queue Management algorithm + * + * Copyright (C) 2011-2012 Kathleen Nichols + * Copyright (C) 2011-2012 Van Jacobson + * + * Implemented on linux by : + * Copyright (C) 2012 Michael D. Taht + * Copyright (C) 2012,2015 Eric Dumazet + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + + +#define DEFAULT_CODEL_LIMIT 1000 + +struct codel_sched_data { + struct codel_params params; + struct codel_vars vars; + struct codel_stats stats; + u32 drop_overlimit; +}; + +/* This is the specific function called from codel_dequeue() + * to dequeue a packet from queue. Note: backlog is handled in + * codel, we dont need to reduce it here. + */ +static struct sk_buff *dequeue_func(struct codel_vars *vars, void *ctx) +{ + struct Qdisc *sch = ctx; + struct sk_buff *skb = __qdisc_dequeue_head(&sch->q); + + if (skb) { + qstats_backlog_sub(sch, qdisc_pkt_len(skb)); + prefetch(&skb->end); /* we'll need skb_shinfo() */ + } + return skb; +} + +static void drop_func(struct sk_buff *skb, void *ctx) +{ + struct Qdisc *sch = ctx; + + qdisc_dequeue_drop(sch, skb, QDISC_DROP_CONGESTED); + qdisc_qstats_drop(sch); +} + +static struct sk_buff *__codel_qdisc_dequeue(struct Qdisc *sch) +{ + struct codel_sched_data *q = qdisc_priv(sch); + struct sk_buff *skb; + + skb = codel_dequeue(sch, &sch->qstats.backlog, &q->params, &q->vars, + &q->stats, qdisc_pkt_len, codel_get_enqueue_time, + drop_func, dequeue_func); + + if (skb) + qdisc_bstats_update(sch, skb); + return skb; +} + +static void codel_dequeue_drop(struct Qdisc *sch) +{ + struct codel_sched_data *q = qdisc_priv(sch); + + if (q->stats.drop_count) { + qdisc_tree_reduce_backlog(sch, q->stats.drop_count, + q->stats.drop_len); + q->stats.drop_count = 0; + q->stats.drop_len = 0; + } +} + +static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch) +{ + struct sk_buff *skb; + + skb = __codel_qdisc_dequeue(sch); + + codel_dequeue_drop(sch); + + return skb; +} + +static struct sk_buff *codel_peek(struct Qdisc *sch) +{ + struct sk_buff *skb = skb_peek(&sch->gso_skb); + + if (!skb) { + skb = __codel_qdisc_dequeue(sch); + + if (skb) { + __skb_queue_head(&sch->gso_skb, skb); + /* it's still part of the queue */ + qdisc_qstats_backlog_inc(sch, skb); + sch->q.qlen++; + } + + codel_dequeue_drop(sch); + } + + return skb; +} + +static int codel_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, + struct sk_buff **to_free) +{ + struct codel_sched_data *q; + + if (likely(qdisc_qlen(sch) < sch->limit)) { + codel_set_enqueue_time(skb); + return qdisc_enqueue_tail(skb, sch); + } + q = qdisc_priv(sch); + WRITE_ONCE(q->drop_overlimit, q->drop_overlimit + 1); + return qdisc_drop_reason(skb, sch, to_free, QDISC_DROP_OVERLIMIT); +} + +static const struct nla_policy codel_policy[TCA_CODEL_MAX + 1] = { + [TCA_CODEL_TARGET] = { .type = NLA_U32 }, + [TCA_CODEL_LIMIT] = { .type = NLA_U32 }, + [TCA_CODEL_INTERVAL] = { .type = NLA_U32 }, + [TCA_CODEL_ECN] = { .type = NLA_U32 }, + [TCA_CODEL_CE_THRESHOLD]= { .type = NLA_U32 }, +}; + +static int codel_change(struct Qdisc *sch, struct nlattr *opt, + struct netlink_ext_ack *extack) +{ + unsigned int dropped_pkts = 0, dropped_bytes = 0; + struct codel_sched_data *q = qdisc_priv(sch); + struct nlattr *tb[TCA_CODEL_MAX + 1]; + int err; + + err = nla_parse_nested_deprecated(tb, TCA_CODEL_MAX, opt, + codel_policy, NULL); + if (err < 0) + return err; + + sch_tree_lock(sch); + + if (tb[TCA_CODEL_TARGET]) { + u32 target = nla_get_u32(tb[TCA_CODEL_TARGET]); + + WRITE_ONCE(q->params.target, + ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT); + } + + if (tb[TCA_CODEL_CE_THRESHOLD]) { + u64 val = nla_get_u32(tb[TCA_CODEL_CE_THRESHOLD]); + + WRITE_ONCE(q->params.ce_threshold, + (val * NSEC_PER_USEC) >> CODEL_SHIFT); + } + + if (tb[TCA_CODEL_INTERVAL]) { + u32 interval = nla_get_u32(tb[TCA_CODEL_INTERVAL]); + + WRITE_ONCE(q->params.interval, + ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT); + } + + if (tb[TCA_CODEL_LIMIT]) + WRITE_ONCE(sch->limit, + nla_get_u32(tb[TCA_CODEL_LIMIT])); + + if (tb[TCA_CODEL_ECN]) + WRITE_ONCE(q->params.ecn, + !!nla_get_u32(tb[TCA_CODEL_ECN])); + + while (sch->q.qlen > sch->limit) { + struct sk_buff *skb = qdisc_dequeue_internal(sch, true); + + if (!skb) + break; + + dropped_pkts++; + dropped_bytes += qdisc_pkt_len(skb); + rtnl_qdisc_drop(skb, sch); + } + qdisc_tree_reduce_backlog(sch, dropped_pkts, dropped_bytes); + + sch_tree_unlock(sch); + return 0; +} + +static int codel_init(struct Qdisc *sch, struct nlattr *opt, + struct netlink_ext_ack *extack) +{ + struct codel_sched_data *q = qdisc_priv(sch); + + sch->limit = DEFAULT_CODEL_LIMIT; + + codel_params_init(&q->params); + codel_vars_init(&q->vars); + codel_stats_init(&q->stats); + q->params.mtu = psched_mtu(qdisc_dev(sch)); + + if (opt) { + int err = codel_change(sch, opt, extack); + + if (err) + return err; + } + + if (sch->limit >= 1) + sch->flags |= TCQ_F_CAN_BYPASS; + else + sch->flags &= ~TCQ_F_CAN_BYPASS; + + sch->flags |= TCQ_F_DEQUEUE_DROPS; + + return 0; +} + +static int codel_dump(struct Qdisc *sch, struct sk_buff *skb) +{ + struct codel_sched_data *q = qdisc_priv(sch); + codel_time_t ce_threshold; + struct nlattr *opts; + + opts = nla_nest_start_noflag(skb, TCA_OPTIONS); + if (opts == NULL) + goto nla_put_failure; + + if (nla_put_u32(skb, TCA_CODEL_TARGET, + codel_time_to_us(READ_ONCE(q->params.target))) || + nla_put_u32(skb, TCA_CODEL_LIMIT, + READ_ONCE(sch->limit)) || + nla_put_u32(skb, TCA_CODEL_INTERVAL, + codel_time_to_us(READ_ONCE(q->params.interval))) || + nla_put_u32(skb, TCA_CODEL_ECN, + READ_ONCE(q->params.ecn))) + goto nla_put_failure; + ce_threshold = READ_ONCE(q->params.ce_threshold); + if (ce_threshold != CODEL_DISABLED_THRESHOLD && + nla_put_u32(skb, TCA_CODEL_CE_THRESHOLD, + codel_time_to_us(ce_threshold))) + goto nla_put_failure; + return nla_nest_end(skb, opts); + +nla_put_failure: + nla_nest_cancel(skb, opts); + return -1; +} + +static int codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d) +{ + const struct codel_sched_data *q = qdisc_priv(sch); + struct tc_codel_xstats st = { + .maxpacket = READ_ONCE(q->stats.maxpacket), + .count = READ_ONCE(q->vars.count), + .lastcount = READ_ONCE(q->vars.lastcount), + .drop_overlimit = READ_ONCE(q->drop_overlimit), + .ldelay = codel_time_to_us(READ_ONCE(q->vars.ldelay)), + .dropping = READ_ONCE(q->vars.dropping), + .ecn_mark = READ_ONCE(q->stats.ecn_mark), + .ce_mark = READ_ONCE(q->stats.ce_mark), + }; + + if (st.dropping) { + codel_tdiff_t delta = READ_ONCE(q->vars.drop_next) - codel_get_time(); + + if (delta >= 0) + st.drop_next = codel_time_to_us(delta); + else + st.drop_next = -codel_time_to_us(-delta); + } + + return gnet_stats_copy_app(d, &st, sizeof(st)); +} + +static void codel_reset(struct Qdisc *sch) +{ + struct codel_sched_data *q = qdisc_priv(sch); + + qdisc_reset_queue(sch); + codel_vars_init(&q->vars); +} + +static struct Qdisc_ops codel_qdisc_ops __read_mostly = { + .id = "codel", + .priv_size = sizeof(struct codel_sched_data), + + .enqueue = codel_qdisc_enqueue, + .dequeue = codel_qdisc_dequeue, + .peek = codel_peek, + .init = codel_init, + .reset = codel_reset, + .change = codel_change, + .dump = codel_dump, + .dump_stats = codel_dump_stats, + .owner = THIS_MODULE, +}; +MODULE_ALIAS_NET_SCH("codel"); + +static int __init codel_module_init(void) +{ + return register_qdisc(&codel_qdisc_ops); +} + +static void __exit codel_module_exit(void) +{ + unregister_qdisc(&codel_qdisc_ops); +} + +module_init(codel_module_init) +module_exit(codel_module_exit) + +MODULE_DESCRIPTION("Controlled Delay queue discipline"); +MODULE_AUTHOR("Dave Taht"); +MODULE_AUTHOR("Eric Dumazet"); +MODULE_LICENSE("Dual BSD/GPL"); -- cgit v1.3.1