6.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: Namhyung Kim namhyung@kernel.org
[ 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@linaro.org Signed-off-by: Namhyung Kim namhyung@kernel.org Cc: Adrian Hunter adrian.hunter@intel.com Cc: Ian Rogers irogers@google.com Cc: Ingo Molnar mingo@kernel.org Cc: Jiri Olsa jolsa@kernel.org Cc: Kan Liang kan.liang@linux.intel.com Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Link: https://lore.kernel.org/r/20240812172533.2015291-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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;