Subject: [PATCH 2/7] libbpf: Return const btf_array from btf_array inline function

From: Jiri Olsa <[email-masked]>
Date: Fri, 6 Sep 2019 09:31:39 +0200

I'm getting following errors when compiling with -Wcast-qual:

  bpf/btf.h: In function ‘btf_array* btf_array(const btf_type*)’:
  bpf/btf.h:254:35: warning: cast from type ‘const btf_type*’ to type
  ‘btf_array*’ casts away qualifiers [-Wcast-qual]
    254 |  return (struct btf_array *)(t + 1);
        |                                   ^

The argument is const so the cast to following struct btf_array
pointer should be const as well. Casting the const away in btf.c
calls where it's correctly used without const in deduplication
code.

Signed-off-by: Jiri Olsa <[email-masked]>
---
 tools/lib/bpf/btf.c | 4 ++--
 tools/lib/bpf/btf.h | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1aa189a9112a..d6327bcc713a 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -2587,7 +2587,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
 		break;
 
 	case BTF_KIND_ARRAY: {
-		struct btf_array *info = btf_array(t);
+		struct btf_array *info = (struct btf_array *) btf_array(t);
 
 		ref_type_id = btf_dedup_ref_type(d, info->type);
 		if (ref_type_id < 0)
@@ -2782,7 +2782,7 @@ static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
 		break;
 
 	case BTF_KIND_ARRAY: {
-		struct btf_array *arr_info = btf_array(t);
+		struct btf_array *arr_info = (struct btf_array *) btf_array(t);
 
 		r = btf_dedup_remap_type_id(d, arr_info->type);
 		if (r < 0)
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 952e3496467d..6bbf5772aa61 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -249,9 +249,9 @@ static inline __u8 btf_int_bits(const struct btf_type *t)
 	return BTF_INT_BITS(*(const __u32 *)(t + 1));
 }
 
-static inline struct btf_array *btf_array(const struct btf_type *t)
+static inline const struct btf_array *btf_array(const struct btf_type *t)
 {
-	return (struct btf_array *)(t + 1);
+	return (const struct btf_array *)(t + 1);
 }
 
 static inline struct btf_enum *btf_enum(const struct btf_type *t)
-- 
2.21.0