6.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: Namhyung Kim <namhyung@xxxxxxxxxx>
[ Upstream commit 040c0f887fdcfe747a3f63c94e9cd29e9ed0b872 ]
The bpf_get_stackid() helper returns a signed type to check whether it
failed to get a stacktrace or not. But it saved the result in u32 and
checked if the value is negative.
376 if (needs_callstack) {
377 pelem->stack_id = bpf_get_stackid(ctx, &stacks,
378 BPF_F_FAST_STACK_CMP | stack_skip);
--> 379 if (pelem->stack_id < 0)
./tools/perf/util/bpf_skel/lock_contention.bpf.c:379 contention_begin()
warn: unsigned 'pelem->stack_id' is never less than zero.
Let's change the type to s32 instead.
Fixes: 6d499a6b3d90277d ("perf lock: Print the number of lost entries for BPF")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240812172533.2015291-1-namhyung@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
tools/perf/util/bpf_skel/lock_data.h | 4 ++--
tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 1 +
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h
index 36af11faad03c..de12892f992f8 100644
--- a/tools/perf/util/bpf_skel/lock_data.h
+++ b/tools/perf/util/bpf_skel/lock_data.h
@@ -7,11 +7,11 @@ struct tstamp_data {
u64 timestamp;
u64 lock;
u32 flags;
- u32 stack_id;
+ s32 stack_id;
};
struct contention_key {
- u32 stack_id;
+ s32 stack_id;
u32 pid;
u64 lock_addr_or_cgroup;
};
diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
index e9028235d7717..d818e30c54571 100644
--- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
+++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h
@@ -15,6 +15,7 @@
typedef __u8 u8;
typedef __u32 u32;
+typedef __s32 s32;
typedef __u64 u64;
typedef __s64 s64;
--
2.43.0
