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 893cef0..e334d01 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,