perf lock contention: Add empty 'struct rq' to satisfy libbpf 'runqueue' type verific...
authorJiri Olsa <jolsa@kernel.org>
Wed, 10 May 2023 18:51:31 +0000 (15:51 -0300)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Wed, 10 May 2023 19:15:04 +0000 (16:15 -0300)
commit760ebc45746b498a36332acefd9e2838a3f8fcf0
tree2a524447dcc6b8eea344423c36bcd5b7a212d56d
parentbfd431cb2c68cbaec7a27b8a979d031f8501301b
perf lock contention: Add empty 'struct rq' to satisfy libbpf 'runqueue' type verification

If 'struct rq' isn't defined in lock_contention.bpf.c 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).

This makes libbpf decide it has incompatible types and then fails to
load the BPF skeleton:

  # perf lock con -ab sleep 1
  libbpf: extern (var ksym) 'runqueues': incompatible types, expected [95] fwd rq, but kernel has [55509] struct rq
  libbpf: failed to load object 'lock_contention_bpf'
  libbpf: failed to load BPF skeleton 'lock_contention_bpf': -22
  Failed to load lock-contention BPF skeleton
  lock contention BPF setup failed
  #

Add it as an empty struct to satisfy that type verification:

  # perf lock con -ab sleep 1
   contended   total wait     max wait     avg wait         type   caller

           2     50.64 us     25.38 us     25.32 us     spinlock   tick_do_update_jiffies64+0x25
           1     26.18 us     26.18 us     26.18 us     spinlock   tick_do_update_jiffies64+0x25
  #

Committer notes:

Extracted from a larger patch as Namhyung had already fixed the other
issues in e53de7b65a3ca59a ("perf lock contention: Fix struct rq lock
access").

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/lkml/ZFVqeKLssg7uzxzI@krava
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tools/perf/util/bpf_skel/lock_contention.bpf.c