bpf: Fix unsigned 'datasec_id' compared with zero in check_pseudo_btf_id

The unsigned variable datasec_id is assigned a return value from the call
to check_pseudo_btf_id(), which may return negative error code.

This fixes the following coccicheck warning:

  ./kernel/bpf/verifier.c:9616:5-15: WARNING: Unsigned expression compared with zero: datasec_id > 0

Fixes: eaa6bcb ("bpf: Introduce bpf_per_cpu_ptr()")
Reported-by: Tosk Robot <[email protected]>
Signed-off-by: Kaixu Xia <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Acked-by: John Fastabend <[email protected]>
Cc: Hao Luo <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: kaixuxiakx

kernel/bpf/verifier.c

@@ -9572,12 +9572,13 @@ static int check_pseudo_btf_id(struct bpf_verifier_env *env,
 			       struct bpf_insn *insn,
 			       struct bpf_insn_aux_data *aux)
 {
-	u32 datasec_id, type, id = insn->imm;
 	const struct btf_var_secinfo *vsi;
 	const struct btf_type *datasec;
 	const struct btf_type *t;
 	const char *sym_name;
 	bool percpu = false;
+	u32 type, id = insn->imm;
+	s32 datasec_id;
 	u64 addr;
 	int i;