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Date:   Mon,  5 Jun 2023 13:27:10 -0700
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Subject: [PATCH v2 2/4] perf bpf: Move the declaration of struct rq
From:   Ian Rogers <irogers@google.com>
To:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        James Clark <james.clark@arm.com>,
        Tiezhu Yang <yangtiezhu@loongson.cn>,
        Yang Jihong <yangjihong1@huawei.com>,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
        bpf@vger.kernel.org
Cc:     Andrii Nakryiko <andrii@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

struct rq is defined in vmlinux.h when the vmlinux.h is generated,
this causes a redefinition failure if it is declared in
lock_contention.bpf.c. Move the definition to vmlinux.h for
consistency with the generated version.

Fixes: 760ebc45746b ("perf lock contention: Add empty 'struct rq' to satisfy libbpf 'runqueue' type verification")
Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/perf/util/bpf_skel/lock_contention.bpf.c |  2 --
 tools/perf/util/bpf_skel/vmlinux/vmlinux.h     | 10 ++++++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index 1d48226ae75d..8d3cfbb3cc65 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -416,8 +416,6 @@ int contention_end(u64 *ctx)
 	return 0;
 }
 
-struct rq {};
-
 extern struct rq runqueues __ksym;
 
 struct rq___old {
diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
index c7ed51b0c1ef..ab84a6e1da5e 100644
--- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
+++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
@@ -171,4 +171,14 @@ struct bpf_perf_event_data_kern {
 	struct perf_sample_data *data;
 	struct perf_event	*event;
 } __attribute__((preserve_access_index));
+
+/*
+ * If 'struct rq' isn't defined for lock_contention.bpf.c, for the sake of
+ * rq___old and rq___new, then the type for the 'runqueue' variable ends up
+ * being a forward declaration (BTF_KIND_FWD) while the kernel has it defined
+ * (BTF_KIND_STRUCT). The definition appears in vmlinux.h rather than
+ * lock_contention.bpf.c for consistency with a generated vmlinux.h.
+ */
+struct rq {};
+
 #endif // __VMLINUX_H
-- 
2.41.0.rc0.172.g3f132b7071-goog