[PATCH v3] tools/lib/bpf: fix -Wdiscarded-qualifiers under C23
From: Mikhail Gavrilov <hidden>
Date: 2025-12-06 08:07:23
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
glibc ≥ 2.42 (GCC 15) defaults to -std=gnu23, which promotes
-Wdiscarded-qualifiers to an error.
In C23, strstr() and strchr() return "const char *".
Declare `res` and `next_path` as const char * — they are never modified.
Keep `sym_sfx` as char * because it is advanced in a loop.
Suggested-by: Florian Weimer <redacted>
Suggested-by: Andrii Nakryiko <redacted>
Signed-off-by: Mikhail Gavrilov <redacted>
---
v2: use const char * where possible (Florian, Andrii)
v3: declare res/next_path as const char * (never modified)
keep cast for sym_sfx (advanced in loop)
---
tools/lib/bpf/libbpf.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3dc8a8078815..81782471f1d0 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c@@ -8484,7 +8484,7 @@ static int kallsyms_cb(unsigned long long sym_addr, char sym_type, struct bpf_object *obj = ctx; const struct btf_type *t; struct extern_desc *ext; - char *res; + const char *res; res = strstr(sym_name, ".llvm."); if (sym_type == 'd' && res)
@@ -11820,7 +11820,7 @@ static int avail_kallsyms_cb(unsigned long long sym_addr, char sym_type, */ char sym_trim[256], *psym_trim = sym_trim, *sym_sfx; - if (!(sym_sfx = strstr(sym_name, ".llvm."))) + if (!(sym_sfx = (char *)strstr(sym_name, ".llvm."))) /* needs mutation */ return 0; /* psym_trim vs sym_trim dance is done to avoid pointer vs array
@@ -12401,7 +12401,7 @@ static int resolve_full_path(const char *file, char *result, size_t result_sz) if (!search_paths[i]) continue; for (s = search_paths[i]; s != NULL; s = strchr(s, ':')) { - char *next_path; + const char *next_path; int seg_len; if (s[0] == ':')
--
2.52.0