we need to daemonize *before* opening the watchdog device

1 files changed, 9 insertions, 4 deletions

diff --git a/miscutils/watchdog.c b/miscutils/watchdog.c
index 893cef0ac..e334d0189 100644
--- a/miscutils/watchdog.c
+++ b/miscutils/watchdog.c
@@ -45,6 +45,15 @@ int watchdog_main(int argc, char **argv)
         opt_complementary = "=1"; /* must have exactly 1 argument */
         opts = getopt32(argv, "Ft:T:", &st_arg, &ht_arg);
 
+        /* We need to daemonize *before* opening the watchdog as many drivers
+         * will only allow one process at a time to do so.  Since daemonizing
+         * is not perfect (child may run before parent finishes exiting), we
+         * can't rely on parent exiting before us (let alone *cleanly* releasing
+         * the watchdog fd -- something else that may not even be allowed).
+         */
+        if (!(opts & OPT_FOREGROUND))
+                bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
+
         if (opts & OPT_HTIMER)
                 htimer_duration = xatou_sfx(ht_arg, suffixes);
         stimer_duration = htimer_duration / 2;
@@ -76,10 +85,6 @@ int watchdog_main(int argc, char **argv)
                 stimer_duration, htimer_duration * 1000);
 #endif
 
-        if (!(opts & OPT_FOREGROUND)) {
-                bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
-        }
-
         while (1) {
                 /*
                  * Make sure we clear the counter before sleeping,