Quentin reported build warnings when building bpftool :
link.c: In function ‘perf_config_hw_cache_str’:
link.c:86:18: warning: comparison of unsigned expression in ‘>= 0’ is always true [-Wtype-limits]
86 | if ((id) >= 0 && (id) < ARRAY_SIZE(array)) \
| ^~
link.c:320:20: note: in expansion of macro ‘perf_event_name’
320 | hw_cache = perf_event_name(evsel__hw_cache, config & 0xff);
| ^~~~~~~~~~~~~~~
[... more of the same for the other calls to perf_event_name ...]
He also pointed out the reason and the solution:
We're always passing unsigned, so it should be safe to drop the check on
(id) >= 0.
Fixes: 62b57e3ddd64 ("bpftool: Add perf event names")
Reported-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
Closes: https://lore.kernel.org/bpf/a35d9a2d-54a0-49ec-9ed1-8fcf1369d3cc@xxxxxxxxxxxxx
Suggested-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Acked-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
---
tools/bpf/bpftool/link.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
index 0b214f6ab5c8..2e5c231e08ac 100644
--- a/tools/bpf/bpftool/link.c
+++ b/tools/bpf/bpftool/link.c
@@ -83,7 +83,7 @@ const char *evsel__hw_cache_result[PERF_COUNT_HW_CACHE_RESULT_MAX] = {
#define perf_event_name(array, id) ({ \
const char *event_str = NULL; \
\
- if ((id) >= 0 && (id) < ARRAY_SIZE(array)) \
+ if ((id) < ARRAY_SIZE(array)) \
event_str = array[id]; \
event_str; \
})
--
2.34.1
