reboot: Only wait for procs if there are any

[Stefan Fritsch]

Hi,

what about only waiting for processes to die on reboot if there are any 
processes left? Nice for the frequently rebooting kernel developer.

This usually saves at least one second and often 4-5 seconds when calling 
reboot via ssh or 'exec reboot' from a console (otherwise the parent shell 
won't exit before the first SIGKILL).

ok?

Cheers,
Stefan

diff --git sbin/reboot/reboot.c sbin/reboot/reboot.c
index dd85d0d9c8c..5556514295e 100644
--- sbin/reboot/reboot.c
+++ sbin/reboot/reboot.c
@@ -57,6 +57,17 @@ int  dohalt;
 
 #define _PATH_RC       "/etc/rc"
 
+static void
+sleep_while_procs(int seconds)
+{
+       while (seconds > 0) {
+               if (kill(-1, 0) == -1 && errno == ESRCH)
+                       return;
+               sleep(1);
+               seconds--;
+       }
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -232,10 +243,10 @@ main(int argc, char *argv[])
         * buffers on their way.  Wait 5 seconds between the SIGTERM and
         * the SIGKILL to give everybody a chance.
         */
-       sleep(2);
+       sleep_while_procs(2);
        if (!nflag)
                sync();
-       sleep(3);
+       sleep_while_procs(3);
 
        for (i = 1;; ++i) {
                if (kill(-1, SIGKILL) == -1) {
@@ -247,7 +258,7 @@ main(int argc, char *argv[])
                        warnx("WARNING: some process(es) wouldn't die");
                        break;
                }
-               (void)sleep(2 * i);
+               sleep_while_procs(2 * i);
        }
 
        reboot(howto);