[PATCH v3 2/4] perf bpf: Move the declaration of struct rq

Ian Rogers
2023-06-09T04:32:59Z

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