net: ipconfig: Relax fw_devlink if we need to mount a network rootfs

If there are network devices that could probe without some of their
suppliers probing and those network devices are needed to mount a
network rootfs, then fw_devlink=on might break that usecase by blocking
the network devices from probing by the time IP auto config starts.

So, if no network devices are available when IP auto config is enabled
and we have a network rootfs, make sure fw_devlink doesn't block the
probing of any device that has a driver and then retry finding a network
device.

Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20220601070707.3946847-6-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Saravana Kannan

net/ipv4/ipconfig.c

@@ -1434,6 +1434,7 @@ __be32 __init root_nfs_parse_addr(char *name)
 static int __init wait_for_devices(void)
 {
 	int i;
+	bool try_init_devs = true;
 
 	for (i = 0; i < DEVICE_WAIT_MAX; i++) {
 		struct net_device *dev;
@@ -1452,6 +1453,11 @@ static int __init wait_for_devices(void)
 		rtnl_unlock();
 		if (found)
 			return 0;
+		if (try_init_devs &&
+		    (ROOT_DEV == Root_NFS || ROOT_DEV == Root_CIFS)) {
+			try_init_devs = false;
+			wait_for_init_devices_probe();
+		}
 		ssleep(1);
 	}
 	return -ENODEV;