![Jesper Dangaard Brouer](/assets/img/avatar_default.png)
The xdp_redirect_cpu sample have some "builtin" monitoring of the tracepoints for xdp_cpumap_*, but it is practical to have an external tool that can monitor these transpoint as an easy way to troubleshoot an application using XDP + cpumap. Specifically I need such external tool when working on Suricata and XDP cpumap redirect. Extend the xdp_monitor tool sample with monitoring of these xdp_cpumap_* tracepoints. Model the output format like xdp_redirect_cpu. Given I needed to handle per CPU decoding for cpumap, this patch also add per CPU info on the existing monitor events. This resembles part of the builtin monitoring output from sample xdp_rxq_info. Thus, also covering part of that sample in an external monitoring tool. Performance wise, the cpumap tracepoints uses bulking, which cause them to have very little overhead. Thus, they are enabled by default. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
211 lines
5.4 KiB
C
211 lines
5.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0
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* Copyright(c) 2017-2018 Jesper Dangaard Brouer, Red Hat Inc.
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*
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* XDP monitor tool, based on tracepoints
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*/
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#include <uapi/linux/bpf.h>
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#include "bpf_helpers.h"
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struct bpf_map_def SEC("maps") redirect_err_cnt = {
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.type = BPF_MAP_TYPE_PERCPU_ARRAY,
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.key_size = sizeof(u32),
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.value_size = sizeof(u64),
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.max_entries = 2,
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/* TODO: have entries for all possible errno's */
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};
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#define XDP_UNKNOWN XDP_REDIRECT + 1
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struct bpf_map_def SEC("maps") exception_cnt = {
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.type = BPF_MAP_TYPE_PERCPU_ARRAY,
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.key_size = sizeof(u32),
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.value_size = sizeof(u64),
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.max_entries = XDP_UNKNOWN + 1,
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};
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/* Tracepoint format: /sys/kernel/debug/tracing/events/xdp/xdp_redirect/format
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* Code in: kernel/include/trace/events/xdp.h
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*/
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struct xdp_redirect_ctx {
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u64 __pad; // First 8 bytes are not accessible by bpf code
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int prog_id; // offset:8; size:4; signed:1;
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u32 act; // offset:12 size:4; signed:0;
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int ifindex; // offset:16 size:4; signed:1;
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int err; // offset:20 size:4; signed:1;
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int to_ifindex; // offset:24 size:4; signed:1;
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u32 map_id; // offset:28 size:4; signed:0;
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int map_index; // offset:32 size:4; signed:1;
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}; // offset:36
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enum {
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XDP_REDIRECT_SUCCESS = 0,
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XDP_REDIRECT_ERROR = 1
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};
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static __always_inline
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int xdp_redirect_collect_stat(struct xdp_redirect_ctx *ctx)
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{
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u32 key = XDP_REDIRECT_ERROR;
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int err = ctx->err;
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u64 *cnt;
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if (!err)
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key = XDP_REDIRECT_SUCCESS;
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cnt = bpf_map_lookup_elem(&redirect_err_cnt, &key);
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if (!cnt)
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return 1;
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*cnt += 1;
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return 0; /* Indicate event was filtered (no further processing)*/
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/*
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* Returning 1 here would allow e.g. a perf-record tracepoint
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* to see and record these events, but it doesn't work well
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* in-practice as stopping perf-record also unload this
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* bpf_prog. Plus, there is additional overhead of doing so.
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*/
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}
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SEC("tracepoint/xdp/xdp_redirect_err")
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int trace_xdp_redirect_err(struct xdp_redirect_ctx *ctx)
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{
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return xdp_redirect_collect_stat(ctx);
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}
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SEC("tracepoint/xdp/xdp_redirect_map_err")
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int trace_xdp_redirect_map_err(struct xdp_redirect_ctx *ctx)
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{
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return xdp_redirect_collect_stat(ctx);
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}
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/* Likely unloaded when prog starts */
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SEC("tracepoint/xdp/xdp_redirect")
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int trace_xdp_redirect(struct xdp_redirect_ctx *ctx)
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{
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return xdp_redirect_collect_stat(ctx);
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}
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/* Likely unloaded when prog starts */
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SEC("tracepoint/xdp/xdp_redirect_map")
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int trace_xdp_redirect_map(struct xdp_redirect_ctx *ctx)
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{
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return xdp_redirect_collect_stat(ctx);
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}
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/* Tracepoint format: /sys/kernel/debug/tracing/events/xdp/xdp_exception/format
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* Code in: kernel/include/trace/events/xdp.h
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*/
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struct xdp_exception_ctx {
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u64 __pad; // First 8 bytes are not accessible by bpf code
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int prog_id; // offset:8; size:4; signed:1;
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u32 act; // offset:12; size:4; signed:0;
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int ifindex; // offset:16; size:4; signed:1;
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};
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SEC("tracepoint/xdp/xdp_exception")
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int trace_xdp_exception(struct xdp_exception_ctx *ctx)
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{
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u64 *cnt;
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u32 key;
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key = ctx->act;
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if (key > XDP_REDIRECT)
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key = XDP_UNKNOWN;
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cnt = bpf_map_lookup_elem(&exception_cnt, &key);
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if (!cnt)
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return 1;
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*cnt += 1;
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return 0;
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}
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/* Common stats data record shared with _user.c */
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struct datarec {
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u64 processed;
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u64 dropped;
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u64 info;
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};
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#define MAX_CPUS 64
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struct bpf_map_def SEC("maps") cpumap_enqueue_cnt = {
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.type = BPF_MAP_TYPE_PERCPU_ARRAY,
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.key_size = sizeof(u32),
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.value_size = sizeof(struct datarec),
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.max_entries = MAX_CPUS,
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};
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struct bpf_map_def SEC("maps") cpumap_kthread_cnt = {
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.type = BPF_MAP_TYPE_PERCPU_ARRAY,
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.key_size = sizeof(u32),
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.value_size = sizeof(struct datarec),
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.max_entries = 1,
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};
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/* Tracepoint: /sys/kernel/debug/tracing/events/xdp/xdp_cpumap_enqueue/format
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* Code in: kernel/include/trace/events/xdp.h
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*/
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struct cpumap_enqueue_ctx {
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u64 __pad; // First 8 bytes are not accessible by bpf code
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int map_id; // offset:8; size:4; signed:1;
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u32 act; // offset:12; size:4; signed:0;
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int cpu; // offset:16; size:4; signed:1;
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unsigned int drops; // offset:20; size:4; signed:0;
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unsigned int processed; // offset:24; size:4; signed:0;
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int to_cpu; // offset:28; size:4; signed:1;
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};
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SEC("tracepoint/xdp/xdp_cpumap_enqueue")
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int trace_xdp_cpumap_enqueue(struct cpumap_enqueue_ctx *ctx)
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{
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u32 to_cpu = ctx->to_cpu;
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struct datarec *rec;
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if (to_cpu >= MAX_CPUS)
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return 1;
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rec = bpf_map_lookup_elem(&cpumap_enqueue_cnt, &to_cpu);
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if (!rec)
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return 0;
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rec->processed += ctx->processed;
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rec->dropped += ctx->drops;
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/* Record bulk events, then userspace can calc average bulk size */
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if (ctx->processed > 0)
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rec->info += 1;
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return 0;
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}
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/* Tracepoint: /sys/kernel/debug/tracing/events/xdp/xdp_cpumap_kthread/format
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* Code in: kernel/include/trace/events/xdp.h
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*/
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struct cpumap_kthread_ctx {
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u64 __pad; // First 8 bytes are not accessible by bpf code
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int map_id; // offset:8; size:4; signed:1;
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u32 act; // offset:12; size:4; signed:0;
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int cpu; // offset:16; size:4; signed:1;
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unsigned int drops; // offset:20; size:4; signed:0;
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unsigned int processed; // offset:24; size:4; signed:0;
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int sched; // offset:28; size:4; signed:1;
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};
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SEC("tracepoint/xdp/xdp_cpumap_kthread")
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int trace_xdp_cpumap_kthread(struct cpumap_kthread_ctx *ctx)
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{
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struct datarec *rec;
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u32 key = 0;
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rec = bpf_map_lookup_elem(&cpumap_kthread_cnt, &key);
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if (!rec)
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return 0;
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rec->processed += ctx->processed;
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rec->dropped += ctx->drops;
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/* Count times kthread yielded CPU via schedule call */
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if (ctx->sched)
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rec->info++;
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return 0;
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}
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