From f1238ea92562f461892a89cad476761bcaa0b514 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Mon, 12 Aug 2024 10:25:33 -0700 Subject: [PATCH] perf lock contention: Change stack_id type to s32 BugLink: https://bugs.launchpad.net/bugs/2089340 [ 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 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 Signed-off-by: Sasha Levin Signed-off-by: Portia Stephens Signed-off-by: Stefan Bader --- tools/perf/util/bpf_skel/lock_data.h | 2 +- tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h index 08482daf61be..8bbefceb66ae 100644 --- a/tools/perf/util/bpf_skel/lock_data.h +++ b/tools/perf/util/bpf_skel/lock_data.h @@ -4,7 +4,7 @@ #define UTIL_BPF_SKEL_LOCK_DATA_H 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 ab84a6e1da5e..fb0bcc1a8033 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;