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    Subject[PATCH bpf-next v1 2/5] cgroup: bpf: add cgroup_rstat_updated() and cgroup_rstat_flush() kfuncs
    From
    Add cgroup_rstat_updated() and cgroup_rstat_flush() kfuncs to bpf
    tracing programs. bpf programs that make use of rstat can use these
    functions to inform rstat when they update stats for a cgroup, and when
    they need to flush the stats.

    Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
    ---
    kernel/cgroup/rstat.c | 35 ++++++++++++++++++++++++++++++++++-
    1 file changed, 34 insertions(+), 1 deletion(-)

    diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
    index e7a88d2600bd..a16a851bc0a1 100644
    --- a/kernel/cgroup/rstat.c
    +++ b/kernel/cgroup/rstat.c
    @@ -3,6 +3,11 @@

    #include <linux/sched/cputime.h>

    +#include <linux/bpf.h>
    +#include <linux/btf.h>
    +#include <linux/btf_ids.h>
    +
    +
    static DEFINE_SPINLOCK(cgroup_rstat_lock);
    static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);

    @@ -141,7 +146,12 @@ static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos,
    return pos;
    }

    -/* A hook for bpf stat collectors to attach to and flush their stats */
    +/*
    + * A hook for bpf stat collectors to attach to and flush their stats.
    + * Together with providing bpf kfuncs for cgroup_rstat_updated() and
    + * cgroup_rstat_flush(), this enables a complete workflow where bpf progs that
    + * collect cgroup stats can integrate with rstat for efficient flushing.
    + */
    __weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
    struct cgroup *parent, int cpu)
    {
    @@ -476,3 +486,26 @@ void cgroup_base_stat_cputime_show(struct seq_file *seq)
    "system_usec %llu\n",
    usage, utime, stime);
    }
    +
    +/* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */
    +BTF_SET_START(bpf_rstat_check_kfunc_ids)
    +BTF_ID(func, cgroup_rstat_updated)
    +BTF_ID(func, cgroup_rstat_flush)
    +BTF_SET_END(bpf_rstat_check_kfunc_ids)
    +
    +BTF_SET_START(bpf_rstat_sleepable_kfunc_ids)
    +BTF_ID(func, cgroup_rstat_flush)
    +BTF_SET_END(bpf_rstat_sleepable_kfunc_ids)
    +
    +static const struct btf_kfunc_id_set bpf_rstat_kfunc_set = {
    + .owner = THIS_MODULE,
    + .check_set = &bpf_rstat_check_kfunc_ids,
    + .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
    +};
    +
    +static int __init bpf_rstat_kfunc_init(void)
    +{
    + return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING,
    + &bpf_rstat_kfunc_set);
    +}
    +late_initcall(bpf_rstat_kfunc_init);
    --
    2.36.1.124.g0e6072fb45-goog
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