| From a4c493ae42926ab36fdc805a5da9f0682bb98b45 Mon Sep 17 00:00:00 2001 |
| From: Matt Spinler <spinler@us.ibm.com> |
| Date: Tue, 13 Jun 2017 15:26:49 -0500 |
| Subject: [PATCH] Stop watchdog first on startup |
| |
| Some watchdog implementations may do things other than issue |
| a reboot on a watchdog timeout. In this case, there's the |
| possibility of restarting this program from the state of |
| the watchdog device not being properly stopped (done by writing |
| a 'V' and closing the device). Since it wasn't stopped, the |
| driver may not be able to restart the watchdog when this program |
| reopens it and starts pinging it. |
| |
| To fix this, the code will always first issue the stop when it |
| starts up. |
| |
| Signed-off-by: Matt Spinler <spinler@us.ibm.com> |
| --- |
| miscutils/watchdog.c | 21 +++++++++++++++++++-- |
| 1 file changed, 19 insertions(+), 2 deletions(-) |
| |
| diff --git a/miscutils/watchdog.c b/miscutils/watchdog.c |
| index 07ae64e52..223e3c32d 100644 |
| --- a/miscutils/watchdog.c |
| +++ b/miscutils/watchdog.c |
| @@ -53,6 +53,24 @@ static void watchdog_shutdown(int sig UNUSED_PARAM) |
| _exit(EXIT_SUCCESS); |
| } |
| |
| +static void watchdog_open(const char* device) |
| +{ |
| + static const char magic_value = 'V'; |
| + |
| + /* If the watchdog driver can do something other than cause a reboot |
| + * on a timeout, then it's possible this program may be starting from |
| + * a state when the watchdog hadn't been previously stopped with |
| + * the magic write followed by a close. In this case the driver may |
| + * not start properly, so always do the proper stop first just in case. |
| + */ |
| + |
| + /* Use known fd # - avoid needing global 'int fd' */ |
| + xmove_fd(xopen(device, O_WRONLY), 3); |
| + write(3, &magic_value, 1); |
| + close(3); |
| + xmove_fd(xopen(device, O_WRONLY), 3); |
| +} |
| + |
| int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| int watchdog_main(int argc, char **argv) |
| { |
| @@ -88,8 +106,7 @@ int watchdog_main(int argc, char **argv) |
| |
| bb_signals(BB_FATAL_SIGS, watchdog_shutdown); |
| |
| - /* Use known fd # - avoid needing global 'int fd' */ |
| - xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3); |
| + watchdog_open(argv[argc - 1]); |
| |
| /* WDIOC_SETTIMEOUT takes seconds, not milliseconds */ |
| htimer_duration = htimer_duration / 1000; |
| -- |
| 2.11.0 |
| |