zebra: remove unnecessary check for default vrf

The default vrf is generally non-NULL, except when shutdown. So, most
of the time it is not necessary to check if it is NULL, we should
remove the useless checks for it.

Searched them with exact match:
```
grep -rI "zebra_vrf_lookup_by_id(VRF_DEFAULT)" | wc -l
31
```

Signed-off-by: anlan_cs <vic.lan@pica8.com>

7 files changed, 2 insertions, 55 deletions

diff --git a/zebra/table_manager.c b/zebra/table_manager.c
index 77ec42e64..512508b79 100644
--- a/zebra/table_manager.c
+++ b/zebra/table_manager.c
@@ -63,8 +63,7 @@ void table_manager_enable(struct zebra_vrf *zvrf)
 	    && strcmp(zvrf_name(zvrf), VRF_DEFAULT_NAME)) {
 		struct zebra_vrf *def = zebra_vrf_lookup_by_id(VRF_DEFAULT);
 
-		if (def)
-			zvrf->tbl_mgr = def->tbl_mgr;
+		zvrf->tbl_mgr = def->tbl_mgr;
 		return;
 	}
 	zvrf->tbl_mgr = XCALLOC(MTYPE_TM_TABLE, sizeof(struct table_manager));
diff --git a/zebra/zapi_msg.c b/zebra/zapi_msg.c
index 5ac875405..6a5b0b4a0 100644
--- a/zebra/zapi_msg.c
+++ b/zebra/zapi_msg.c
@@ -1337,8 +1337,6 @@ static void zread_fec_register(ZAPI_HANDLER_ARGS)
 
 	s = msg;
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return;
 
 	/*
 	 * The minimum amount of data that can be sent for one fec
@@ -1400,8 +1398,6 @@ static void zread_fec_unregister(ZAPI_HANDLER_ARGS)
 
 	s = msg;
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return;
 
 	/*
 	 * The minimum amount of data that can be sent for one
diff --git a/zebra/zebra_mpls.c b/zebra/zebra_mpls.c
index ef109774d..eac4fcc8e 100644
--- a/zebra/zebra_mpls.c
+++ b/zebra/zebra_mpls.c
@@ -1029,8 +1029,6 @@ static void lsp_processq_del(struct work_queue *wq, void *data)
 		return;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	assert(zvrf);
-
 	lsp_table = zvrf->lsp_table;
 	if (!lsp_table) // unexpected
 		return;
@@ -1776,9 +1774,6 @@ void zebra_mpls_lsp_dplane_result(struct zebra_dplane_ctx *ctx)
 	case DPLANE_OP_LSP_UPDATE:
 		/* Look for zebra LSP object */
 		zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-		if (zvrf == NULL)
-			break;
-
 		lsp_table = zvrf->lsp_table;
 
 		tmp_ile.in_label = label;
@@ -2093,9 +2088,6 @@ void zebra_mpls_process_dplane_notify(struct zebra_dplane_ctx *ctx)
 
 	/* Look for zebra LSP object */
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (zvrf == NULL)
-		return;
-
 	lsp_table = zvrf->lsp_table;
 
 	tmp_ile.in_label = dplane_ctx_get_in_label(ctx);
diff --git a/zebra/zebra_mpls_vty.c b/zebra/zebra_mpls_vty.c
index 6b8859e0c..e64e7009b 100644
--- a/zebra/zebra_mpls_vty.c
+++ b/zebra/zebra_mpls_vty.c
@@ -42,10 +42,6 @@ static int zebra_mpls_transit_lsp(struct vty *vty, int add_cmd,
 	}
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf) {
-		vty_out(vty, "%% Default VRF does not exist\n");
-		return CMD_WARNING_CONFIG_FAILED;
-	}
 
 	if (!inlabel_str) {
 		vty_out(vty, "%% No Label Information\n");
@@ -186,10 +182,6 @@ static int zebra_mpls_bind(struct vty *vty, int add_cmd, const char *prefix,
 	int ret;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf) {
-		vty_out(vty, "%% Default VRF does not exist\n");
-		return CMD_WARNING_CONFIG_FAILED;
-	}
 
 	memset(&p, 0, sizeof(p));
 	ret = str2prefix(prefix, &p);
@@ -274,8 +266,6 @@ static int zebra_mpls_config(struct vty *vty)
 	struct zebra_vrf *zvrf;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return 0;
 
 	write += zebra_mpls_write_lsp_config(vty, zvrf);
 	write += zebra_mpls_write_fec_config(vty, zvrf);
@@ -297,8 +287,6 @@ DEFUN (show_mpls_fec,
 	int ret;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return 0;
 
 	if (argc == 3)
 		zebra_mpls_print_fec_table(vty, zvrf);
@@ -373,10 +361,6 @@ static int zebra_mpls_global_block(struct vty *vty, int add_cmd,
 	struct zebra_vrf *zvrf;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf) {
-		vty_out(vty, "%% Default VRF does not exist\n");
-		return CMD_WARNING_CONFIG_FAILED;
-	}
 
 	if (add_cmd) {
 		if (!start_label_str || !end_label_str) {
diff --git a/zebra/zebra_pw.c b/zebra/zebra_pw.c
index 12dcac1de..f76bf747d 100644
--- a/zebra/zebra_pw.c
+++ b/zebra/zebra_pw.c
@@ -408,8 +408,6 @@ DEFUN_NOSH (pseudowire_if,
 	int idx = 0;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return CMD_WARNING;
 
 	argv_find(argv, argc, "IFNAME", &idx);
 	ifname = argv[idx]->arg;
@@ -440,8 +438,6 @@ DEFUN (no_pseudowire_if,
 	int idx = 0;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return CMD_WARNING;
 
 	argv_find(argv, argc, "IFNAME", &idx);
 	ifname = argv[idx]->arg;
@@ -564,8 +560,6 @@ DEFUN (show_pseudowires,
 	struct zebra_pw *pw;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return 0;
 
 	vty_out(vty, "%-16s %-24s %-12s %-8s %-10s\n", "Interface", "Neighbor",
 		"Labels", "Protocol", "Status");
@@ -603,8 +597,6 @@ static void vty_show_mpls_pseudowire_detail(struct vty *vty)
 	struct nexthop_group *nhg;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return;
 
 	RB_FOREACH (pw, zebra_pw_head, &zvrf->pseudowires) {
 		char buf_nbr[INET6_ADDRSTRLEN];
@@ -759,8 +751,6 @@ static void vty_show_mpls_pseudowire_detail_json(struct vty *vty)
 	struct zebra_pw *pw;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return;
 
 	json = json_object_new_object();
 	json_pws = json_object_new_array();
@@ -795,8 +785,6 @@ static int zebra_pw_config(struct vty *vty)
 	struct zebra_pw *pw;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return 0;
 
 	RB_FOREACH (pw, zebra_static_pw_head, &zvrf->static_pseudowires) {
 		vty_out(vty, "pseudowire %s\n", pw->ifname);
diff --git a/zebra/zebra_vty.c b/zebra/zebra_vty.c
index d100dc0e6..19366eb2c 100644
--- a/zebra/zebra_vty.c
+++ b/zebra/zebra_vty.c
@@ -2703,13 +2703,8 @@ DEFUN (default_vrf_vni_mapping,
        "Prefix routes only \n")
 {
 	char xpath[XPATH_MAXLEN];
-	struct zebra_vrf *zvrf = NULL;
 	int filter = 0;
 
-	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return CMD_WARNING;
-
 	if (argc == 3)
 		filter = 1;
 
@@ -2746,8 +2741,6 @@ DEFUN (no_default_vrf_vni_mapping,
 	struct zebra_vrf *zvrf = NULL;
 
 	zvrf = zebra_vrf_lookup_by_id(VRF_DEFAULT);
-	if (!zvrf)
-		return CMD_WARNING;
 
 	if (argc == 4)
 		filter = 1;
diff --git a/zebra/zebra_vxlan.c b/zebra/zebra_vxlan.c
index 132862e69..417f83023 100644
--- a/zebra/zebra_vxlan.c
+++ b/zebra/zebra_vxlan.c
@@ -5937,8 +5937,6 @@ static void zebra_vxlan_sg_del(struct zebra_vxlan_sg *vxlan_sg)
 	struct zebra_vrf *zvrf;
 
 	zvrf = vrf_info_lookup(VRF_DEFAULT);
-	if (!zvrf)
-		return;
 
 	/* On SG entry deletion remove the reference to its parent XG
 	 * entry
@@ -6008,8 +6006,6 @@ void zebra_vxlan_sg_deref(struct in_addr local_vtep_ip,
 		return;
 
 	zvrf = vrf_info_lookup(VRF_DEFAULT);
-	if (!zvrf)
-		return;
 
 	zebra_vxlan_sg_do_deref(zvrf, local_vtep_ip, mcast_grp);
 }
@@ -6023,8 +6019,7 @@ void zebra_vxlan_sg_ref(struct in_addr local_vtep_ip, struct in_addr mcast_grp)
 		return;
 
 	zvrf = vrf_info_lookup(VRF_DEFAULT);
-	if (!zvrf)
-		return;
+
 	zebra_vxlan_sg_do_ref(zvrf, local_vtep_ip, mcast_grp);
 }