commit aafa5b9ebad920af7c6ff22c6e16ac75799c7ba4
from: Stefan Sperling <stsp@stsp.name>
date: Thu Oct 10 09:19:57 2024 UTC

show a hint when the user tries to re-parent a running vlan interface

commit - 21775861a453dd25aacb50e76637bdec1d1a31cf
commit + aafa5b9ebad920af7c6ff22c6e16ac75799c7ba4
blob - 031502710a5c7be123a4d9e6bd7367f75378b4f7
blob + 29f1c615442fac653bde22d3c8cf5420169066c4
--- if.c
+++ if.c
@@ -2374,9 +2374,13 @@ intparent(char *ifname, int ifs, int argc, char **argv
 		return 0;
 	}
 
-	if (ioctl(ifs, set ? SIOCSIFPARENT : SIOCDIFPARENT, &ifp) == -1)
+	if (ioctl(ifs, set ? SIOCSIFPARENT : SIOCDIFPARENT, &ifp) == -1) {
 		printf("%% intparent: SIOC%sIFPARENT: %s\n", set ? "S" : "D",
 		    strerror(errno));
+		if (errno == EBUSY)
+			printf("%% 'shutdown %s' required before the parent "
+			"interface can be changed\n", ifname);
+	}
 
 	return 0;
 }