selftests/bpf: Return true/false (not 1/0) from bool functions

Return boolean values ("true" or "false") instead of 1 or 0 from bool
functions.  This fixes the following warnings from coccicheck:

tools/testing/selftests/bpf/progs/test_xdp_noinline.c:407:9-10: WARNING:
return of 0/1 in function 'decap_v4' with return type bool
tools/testing/selftests/bpf/progs/test_xdp_noinline.c:389:9-10: WARNING:
return of 0/1 in function 'decap_v6' with return type bool
tools/testing/selftests/bpf/progs/test_xdp_noinline.c:290:9-10: WARNING:
return of 0/1 in function 'encap_v6' with return type bool
tools/testing/selftests/bpf/progs/test_xdp_noinline.c:264:9-10: WARNING:
return of 0/1 in function 'parse_tcp' with return type bool
tools/testing/selftests/bpf/progs/test_xdp_noinline.c:242:9-10: WARNING:
return of 0/1 in function 'parse_udp' with return type bool

Generated by: scripts/coccinelle/misc/boolreturn.cocci

Suggested-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Linkui Xiao <xiaolinkui@kylinos.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20220714015647.25074-1-xiaolinkui@kylinos.cn

tools/testing/selftests/bpf/progs/test_xdp_noinline.c

@@ -239,15 +239,15 @@ bool parse_udp(void *data, void *data_end,
 	udp = data + off;
 
 	if (udp + 1 > data_end)
-		return 0;
+		return false;
 	if (!is_icmp) {
 		pckt->flow.port16[0] = udp->source;
 		pckt->flow.port16[1] = udp->dest;
 	} else {
 		pckt->flow.port16[0] = udp->dest;
 		pckt->flow.port16[1] = udp->source;
 	}
-	return 1;
+	return true;
 }
 
 static __attribute__ ((noinline))
@@ -261,7 +261,7 @@ bool parse_tcp(void *data, void *data_end,
 
 	tcp = data + off;
 	if (tcp + 1 > data_end)
-		return 0;
+		return false;
 	if (tcp->syn)
 		pckt->flags |= (1 << 1);
 	if (!is_icmp) {
@@ -271,7 +271,7 @@ bool parse_tcp(void *data, void *data_end,
 		pckt->flow.port16[0] = tcp->dest;
 		pckt->flow.port16[1] = tcp->source;
 	}
-	return 1;
+	return true;
 }
 
 static __attribute__ ((noinline))
@@ -287,15 +287,15 @@ bool encap_v6(struct xdp_md *xdp, struct ctl_value *cval,
 	void *data;
 
 	if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct ipv6hdr)))
-		return 0;
+		return false;
 	data = (void *)(long)xdp->data;
 	data_end = (void *)(long)xdp->data_end;
 	new_eth = data;
 	ip6h = data + sizeof(struct eth_hdr);
 	old_eth = data + sizeof(struct ipv6hdr);
 	if (new_eth + 1 > data_end ||
 	    old_eth + 1 > data_end || ip6h + 1 > data_end)
-		return 0;
+		return false;
 	memcpy(new_eth->eth_dest, cval->mac, 6);
 	memcpy(new_eth->eth_source, old_eth->eth_dest, 6);
 	new_eth->eth_proto = 56710;
@@ -314,7 +314,7 @@ bool encap_v6(struct xdp_md *xdp, struct ctl_value *cval,
 	ip6h->saddr.in6_u.u6_addr32[2] = 3;
 	ip6h->saddr.in6_u.u6_addr32[3] = ip_suffix;
 	memcpy(ip6h->daddr.in6_u.u6_addr32, dst->dstv6, 16);
-	return 1;
+	return true;
 }
 
 static __attribute__ ((noinline))
@@ -335,15 +335,15 @@ bool encap_v4(struct xdp_md *xdp, struct ctl_value *cval,
 	ip_suffix <<= 15;
 	ip_suffix ^= pckt->flow.src;
 	if (bpf_xdp_adjust_head(xdp, 0 - (int)sizeof(struct iphdr)))
-		return 0;
+		return false;
 	data = (void *)(long)xdp->data;
 	data_end = (void *)(long)xdp->data_end;
 	new_eth = data;
 	iph = data + sizeof(struct eth_hdr);
 	old_eth = data + sizeof(struct iphdr);
 	if (new_eth + 1 > data_end ||
 	    old_eth + 1 > data_end || iph + 1 > data_end)
-		return 0;
+		return false;
 	memcpy(new_eth->eth_dest, cval->mac, 6);
 	memcpy(new_eth->eth_source, old_eth->eth_dest, 6);
 	new_eth->eth_proto = 8;
@@ -367,8 +367,8 @@ bool encap_v4(struct xdp_md *xdp, struct ctl_value *cval,
 		csum += *next_iph_u16++;
 	iph->check = ~((csum & 0xffff) + (csum >> 16));
 	if (bpf_xdp_adjust_head(xdp, (int)sizeof(struct iphdr)))
-		return 0;
-	return 1;
+		return false;
+	return true;
 }
 
 static __attribute__ ((noinline))
@@ -386,10 +386,10 @@ bool decap_v6(struct xdp_md *xdp, void **data, void **data_end, bool inner_v4)
 	else
 		new_eth->eth_proto = 56710;
 	if (bpf_xdp_adjust_head(xdp, (int)sizeof(struct ipv6hdr)))
-		return 0;
+		return false;
 	*data = (void *)(long)xdp->data;
 	*data_end = (void *)(long)xdp->data_end;
-	return 1;
+	return true;
 }
 
 static __attribute__ ((noinline))
@@ -404,10 +404,10 @@ bool decap_v4(struct xdp_md *xdp, void **data, void **data_end)
 	memcpy(new_eth->eth_dest, old_eth->eth_dest, 6);
 	new_eth->eth_proto = 8;
 	if (bpf_xdp_adjust_head(xdp, (int)sizeof(struct iphdr)))
-		return 0;
+		return false;
 	*data = (void *)(long)xdp->data;
 	*data_end = (void *)(long)xdp->data_end;
-	return 1;
+	return true;
 }
 
 static __attribute__ ((noinline))