tc: fix compilation with old gcc (< 4.6)

gcc < 4.6 does not handle C11 syntax for the static initialization of
anonymous struct/union, hence the following error:

tc_bpf.c:260: error: unknown field map_type specified in initializer
Signed-off-by: Julien Floret <julien.floret@6wind.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>

tc/tc_bpf.c

@@ -257,12 +257,14 @@ static bool bpf_may_skip_map_creation(int file_fd)
 static int bpf_create_map(enum bpf_map_type type, unsigned int size_key,
 			  unsigned int size_value, unsigned int max_elem)
 {
-	union bpf_attr attr = {
-		.map_type	= type,
-		.key_size	= size_key,
-		.value_size	= size_value,
-		.max_entries	= max_elem,
-	};
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+
+	attr.map_type = type;
+	attr.key_size = size_key;
+	attr.value_size = size_value;
+	attr.max_entries = max_elem;
 
 	return bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
 }
@@ -270,12 +272,14 @@ static int bpf_create_map(enum bpf_map_type type, unsigned int size_key,
 static int bpf_update_map(int fd, const void *key, const void *value,
 			  uint64_t flags)
 {
-	union bpf_attr attr = {
-		.map_fd		= fd,
-		.key		= bpf_ptr_to_u64(key),
-		.value		= bpf_ptr_to_u64(value),
-		.flags		= flags,
-	};
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+
+	attr.map_fd = fd;
+	attr.key = bpf_ptr_to_u64(key);
+	attr.value = bpf_ptr_to_u64(value);
+	attr.flags = flags;
 
 	return bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
 }
@@ -283,15 +287,17 @@ static int bpf_update_map(int fd, const void *key, const void *value,
 static int bpf_prog_load(enum bpf_prog_type type, const struct bpf_insn *insns,
 			 unsigned int len, const char *license)
 {
-	union bpf_attr attr = {
-		.prog_type	= type,
-		.insns		= bpf_ptr_to_u64(insns),
-		.insn_cnt	= len / sizeof(struct bpf_insn),
-		.license	= bpf_ptr_to_u64(license),
-		.log_buf	= bpf_ptr_to_u64(bpf_log_buf),
-		.log_size	= sizeof(bpf_log_buf),
-		.log_level	= 1,
-	};
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+
+	attr.prog_type = type;
+	attr.insns = bpf_ptr_to_u64(insns);
+	attr.insn_cnt = len / sizeof(struct bpf_insn);
+	attr.license = bpf_ptr_to_u64(license);
+	attr.log_buf = bpf_ptr_to_u64(bpf_log_buf);
+	attr.log_size = sizeof(bpf_log_buf);
+	attr.log_level = 1;
 
 	return bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
 }