[PATCH] perf lock contention: Fix struct rq lock access

From: Namhyung Kim
Date: Sun Apr 23 2023 - 17:57:00 EST


The BPF CO-RE's ignore suffix rule requires three underscores.
Otherwise it'd fail like below:

$ sudo perf lock contention -ab
libbpf: prog 'collect_lock_syms': BPF program load failed: Invalid argument
libbpf: prog 'collect_lock_syms': -- BEGIN PROG LOAD LOG --
reg type unsupported for arg#0 function collect_lock_syms#380
; int BPF_PROG(collect_lock_syms)
0: (b7) r6 = 0 ; R6_w=0
1: (b7) r7 = 0 ; R7_w=0
2: (b7) r9 = 1 ; R9_w=1
3: <invalid CO-RE relocation>
failed to resolve CO-RE relocation <byte_off> [381] struct rq__new.__lock (0:0 @ offset 0)

Fixes: 0c1228486bef ("perf lock contention: Support pre-5.14 kernels")
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
tools/perf/util/bpf_skel/lock_contention.bpf.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index 8911e2a077d8..30c193078bdb 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -418,11 +418,11 @@ int contention_end(u64 *ctx)

extern struct rq runqueues __ksym;

-struct rq__old {
+struct rq___old {
raw_spinlock_t lock;
} __attribute__((preserve_access_index));

-struct rq__new {
+struct rq___new {
raw_spinlock_t __lock;
} __attribute__((preserve_access_index));

@@ -434,8 +434,8 @@ 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;
+ struct rq___new *rq_new = (void *)rq;
+ struct rq___old *rq_old = (void *)rq;

if (rq == NULL)
break;
--
2.40.0.634.g4ca3ef3211-goog