Call sysctl_ifnames() with shared netlock

[Vitaliy Makkoveev]

It performs read-only access to netlock protected data.

Index: sys/net/rtsock.c
===================================================================
RCS file: /cvs/src/sys/net/rtsock.c,v
retrieving revision 1.359
diff -u -p -r1.359 rtsock.c
--- sys/net/rtsock.c    22 Jan 2023 12:05:44 -0000      1.359
+++ sys/net/rtsock.c    16 Apr 2023 22:15:13 -0000
@@ -2193,9 +2193,9 @@ sysctl_rtable(int *name, u_int namelen, 
                    &tableinfo, sizeof(tableinfo));
                return (error);
        case NET_RT_IFNAMES:
-               NET_LOCK();
+               NET_LOCK_SHARED();
                error = sysctl_ifnames(&w);
-               NET_UNLOCK();
+               NET_UNLOCK_SHARED();
                break;
        case NET_RT_SOURCE:
                tableid = w.w_arg;