From 040c0f887fdcfe747a3f63c94e9cd29e9ed0b872 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Mon, 12 Aug 2024 10:25:33 -0700 Subject: perf lock contention: Change stack_id type to s32 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 Signed-off-by: Namhyung Kim Cc: Adrian Hunter Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20240812172533.2015291-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- 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(-) (limited to 'tools/perf/util') diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h index 36af11faad03..de12892f992f 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 e9028235d771..d818e30c5457 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; -- cgit v1.2.3