T6629: call check_kmod within a standard config function

Move the remaining calls to check_kmod within a standard function,
with placement determined by the needs of the config script.

(cherry picked from commit 95eef73)

src/conf_mode/interfaces_l2tpv3.py

@@ -86,6 +86,8 @@ def generate(l2tpv3):
     return None
 
 def apply(l2tpv3):
+    check_kmod(k_mod)
+
     # Check if L2TPv3 interface already exists
     if interface_exists(l2tpv3['ifname']):
         # L2TPv3 is picky when changing tunnels/sessions, thus we can simply
@@ -102,7 +104,6 @@ def apply(l2tpv3):
 
 if __name__ == '__main__':
     try:
-        check_kmod(k_mod)
         c = get_config()
         verify(c)
         generate(c)

src/conf_mode/interfaces_wireguard.py

@@ -104,6 +104,8 @@ def verify(wireguard):
         public_keys.append(peer['public_key'])
 
 def apply(wireguard):
+    check_kmod('wireguard')
+
     if 'rebuild_required' in wireguard or 'deleted' in wireguard:
         wg = WireGuardIf(**wireguard)
         # WireGuard only supports peer removal based on the configured public-key,
@@ -123,7 +125,6 @@ def apply(wireguard):
 
 if __name__ == '__main__':
     try:
-        check_kmod('wireguard')
         c = get_config()
         verify(c)
         apply(c)

src/conf_mode/interfaces_wireless.py

@@ -225,6 +225,8 @@ def verify(wifi):
     return None
 
 def generate(wifi):
+    check_kmod('mac80211')
+
     interface = wifi['ifname']
 
     # Delete config files if interface is removed
@@ -319,7 +321,6 @@ def apply(wifi):
 
 if __name__ == '__main__':
     try:
-        check_kmod('mac80211')
         c = get_config()
         verify(c)
         generate(c)

src/conf_mode/nat.py

@@ -240,6 +240,8 @@ def generate(nat):
     return None
 
 def apply(nat):
+    check_kmod(k_mod)
+
     cmd(f'nft --file {nftables_nat_config}')
     cmd(f'nft --file {nftables_static_nat_conf}')
 
@@ -253,7 +255,6 @@ def apply(nat):
 
 if __name__ == '__main__':
     try:
-        check_kmod(k_mod)
         c = get_config()
         verify(c)
         generate(c)

src/conf_mode/nat66.py

@@ -112,14 +112,15 @@ def apply(nat):
     if not nat:
         return None
 
+    check_kmod(k_mod)
+
     cmd(f'nft --file {nftables_nat66_config}')
     call_dependents()
 
     return None
 
 if __name__ == '__main__':
     try:
-        check_kmod(k_mod)
         c = get_config()
         verify(c)
         generate(c)