we need to daemonize *before* opening the watchdog device

diff --git a/miscutils/watchdog.c b/miscutils/watchdog.c
index 893cef0ac8989897427c1142b1e8c3f7a5658134..e334d0189cd5537b77f81c78e6b9d8238f7b6d8d 100644 (file)
--- 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,