bpf: Remove BPF_MAP_OFF_ARR_MAX

In f71b2f64 ("bpf: Refactor map->off_arr handling"), map->off_arr
was refactored to be btf_field_offs. The number of field offsets is
equal to maximum possible fields limited by BTF_FIELDS_MAX. Hence, reuse
BTF_FIELDS_MAX as spin_lock and timer no longer are to be handled
specially for offset sorting, fix the comment, and remove incorrect
WARN_ON as its rec->cnt can never exceed this value. The reason to keep
separate constant was the it was always more 2 more than total kptrs.
This is no longer the case.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221114191547.1694267-3-memxor@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/bpf.h

@@ -165,9 +165,8 @@ struct bpf_map_ops {
 };
 
 enum {
-	/* Support at most 8 pointers in a BTF type */
+	/* Support at most 10 fields in a BTF type */
 	BTF_FIELDS_MAX	   = 10,
-	BPF_MAP_OFF_ARR_MAX   = BTF_FIELDS_MAX,
 };
 
 enum btf_field_type {
@@ -203,8 +202,8 @@ struct btf_record {
 
 struct btf_field_offs {
 	u32 cnt;
-	u32 field_off[BPF_MAP_OFF_ARR_MAX];
-	u8 field_sz[BPF_MAP_OFF_ARR_MAX];
+	u32 field_off[BTF_FIELDS_MAX];
+	u8 field_sz[BTF_FIELDS_MAX];
 };
 
 struct bpf_map {

kernel/bpf/btf.c

@@ -3584,7 +3584,7 @@ struct btf_field_offs *btf_parse_field_offs(struct btf_record *rec)
 	u8 *sz;
 
 	BUILD_BUG_ON(ARRAY_SIZE(foffs->field_off) != ARRAY_SIZE(foffs->field_sz));
-	if (IS_ERR_OR_NULL(rec) || WARN_ON_ONCE(rec->cnt > sizeof(foffs->field_off)))
+	if (IS_ERR_OR_NULL(rec))
 		return NULL;
 
 	foffs = kzalloc(sizeof(*foffs), GFP_KERNEL | __GFP_NOWARN);