module-setup: do not add duplicate ip=xxx

In case of iscsi boot, kernel cmdline will contain ip=xxx kernel
parameter for dracut setting up iscsi root in initramfs. For example:

"root=xxx ip=192.168.3.26:::255.255.255.0:localhost.localdomain:eno19:none ..."

dracut doesn't allow duplicate ip conf for the same network card. dracut
will not ignore the either of the duplicate. Instead, it refuses to
continue:

[   15.876306] dracut: FATAL: For argument 'ip=192.168.3.26:::255.255.255.0:localhost.localdomain:eno19:none'\n
Duplication configurations for 'eno19'
[   16.055513] dracut: Refusing to continue ev argument for multiple ip= lines

That's why in our code we don't add a duplicate ip conf when handling
the same network card the second time. But we never consider the case
that ip conf is already added in kernel cmdline for some special
purpose, for example, iscsi boot.

Now we also look up /proc/cmdline for ip conf. If it exists, we use the
existing one. The existing one should work out of box because dracut
will handle it in second kernel like it does for first kernel. That
said, the network card will be brought up and root disk will be mounted
under /sysroot.

Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>

dracut-module-setup.sh

@@ -234,7 +234,10 @@ kdump_setup_netdev() {
 
     # dracut doesn't allow duplicated configuration for same NIC, even they're exactly the same.
     # so we have to avoid adding duplicates
-    if [ ! -f $_ip_conf ] || ! grep -q $_ip_opts $_ip_conf; then
+    # We should also check /proc/cmdline for existing ip=xx arg.
+    # For example, iscsi boot will specify ip=xxx arg in cmdline.
+    if [ ! -f $_ip_conf ] || ! grep -q $_ip_opts $_ip_conf &&\
+        ! grep -q "ip=[^[:space:]]*$_netdev" /proc/cmdline; then
         echo "$_ip_opts" >> $_ip_conf
     fi