linux-kernel - Re: [PATCH v1 1/2] perf lock contention: Support pre-5.14 kernels

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Date:   Mon, 10 Apr 2023 08:33:50 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH v1 1/2] perf lock contention: Support pre-5.14 kernels

Hi Ian,

On Fri, Apr 7, 2023 at 10:52 PM Ian Rogers <irogers@...gle.com> wrote:
>
> struct rq's variable __lock was renamed from lock in 5.14.
>
> Signed-off-by: Ian Rogers <irogers@...gle.com>

Thanks for fixing this.

Acked-by: Namhyung Kim <namhyung@...nel.org>

Thanks,
Namhyung


> ---
>  tools/perf/util/bpf_skel/lock_contention.bpf.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> index 23f6e63544ed..8911e2a077d8 100644
> --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> @@ -418,6 +418,14 @@ int contention_end(u64 *ctx)
>
>  extern struct rq runqueues __ksym;
>
> +struct rq__old {
> +       raw_spinlock_t lock;
> +} __attribute__((preserve_access_index));
> +
> +struct rq__new {
> +       raw_spinlock_t __lock;
> +} __attribute__((preserve_access_index));
> +
>  SEC("raw_tp/bpf_test_finish")
>  int BPF_PROG(collect_lock_syms)
>  {
> @@ -426,11 +434,16 @@ int BPF_PROG(collect_lock_syms)
>
>         for (int i = 0; i < MAX_CPUS; i++) {
>                 struct rq *rq = bpf_per_cpu_ptr(&runqueues, i);
> +               struct rq__new *rq_new = (void *)rq;
> +               struct rq__old *rq_old = (void *)rq;
>
>                 if (rq == NULL)
>                         break;
>
> -               lock_addr = (__u64)&rq->__lock;
> +               if (bpf_core_field_exists(rq_new->__lock))
> +                       lock_addr = (__u64)&rq_new->__lock;
> +               else
> +                       lock_addr = (__u64)&rq_old->lock;
>                 lock_flag = LOCK_CLASS_RQLOCK;
>                 bpf_map_update_elem(&lock_syms, &lock_addr, &lock_flag, BPF_ANY);
>         }
> --
> 2.40.0.577.gac1e443424-goog
>