Use the well defined helper sizeof_field() to calculate the size of a
struct member, instead of doing custom calculations.

Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
---
 kernel/bpf/arena.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c
index 86571e760dd6..af5cae640669 100644
--- a/kernel/bpf/arena.c
+++ b/kernel/bpf/arena.c
@@ -37,7 +37,7 @@
  */
 
 /* number of bytes addressable by LDX/STX insn with 16-bit 'off' field */
-#define GUARD_SZ (1ull << sizeof(((struct bpf_insn *)0)->off) * 8)
+#define GUARD_SZ (1ull << sizeof_field(struct bpf_insn, off) * 8)
 #define KERN_VM_SZ ((1ull << 32) + GUARD_SZ)
 
 struct bpf_arena {
-- 
2.43.2