Matt Spinler | cd9d130 | 2017-06-13 15:42:39 -0500 | [diff] [blame] | 1 | From a4c493ae42926ab36fdc805a5da9f0682bb98b45 Mon Sep 17 00:00:00 2001 |
| 2 | From: Matt Spinler <spinler@us.ibm.com> |
| 3 | Date: Tue, 13 Jun 2017 15:26:49 -0500 |
| 4 | Subject: [PATCH] Stop watchdog first on startup |
| 5 | |
| 6 | Some watchdog implementations may do things other than issue |
| 7 | a reboot on a watchdog timeout. In this case, there's the |
| 8 | possibility of restarting this program from the state of |
| 9 | the watchdog device not being properly stopped (done by writing |
| 10 | a 'V' and closing the device). Since it wasn't stopped, the |
| 11 | driver may not be able to restart the watchdog when this program |
| 12 | reopens it and starts pinging it. |
| 13 | |
| 14 | To fix this, the code will always first issue the stop when it |
| 15 | starts up. |
| 16 | |
| 17 | Signed-off-by: Matt Spinler <spinler@us.ibm.com> |
| 18 | --- |
| 19 | miscutils/watchdog.c | 21 +++++++++++++++++++-- |
| 20 | 1 file changed, 19 insertions(+), 2 deletions(-) |
| 21 | |
| 22 | diff --git a/miscutils/watchdog.c b/miscutils/watchdog.c |
| 23 | index 07ae64e52..223e3c32d 100644 |
| 24 | --- a/miscutils/watchdog.c |
| 25 | +++ b/miscutils/watchdog.c |
| 26 | @@ -53,6 +53,24 @@ static void watchdog_shutdown(int sig UNUSED_PARAM) |
| 27 | _exit(EXIT_SUCCESS); |
| 28 | } |
| 29 | |
| 30 | +static void watchdog_open(const char* device) |
| 31 | +{ |
| 32 | + static const char magic_value = 'V'; |
| 33 | + |
| 34 | + /* If the watchdog driver can do something other than cause a reboot |
| 35 | + * on a timeout, then it's possible this program may be starting from |
| 36 | + * a state when the watchdog hadn't been previously stopped with |
| 37 | + * the magic write followed by a close. In this case the driver may |
| 38 | + * not start properly, so always do the proper stop first just in case. |
| 39 | + */ |
| 40 | + |
| 41 | + /* Use known fd # - avoid needing global 'int fd' */ |
| 42 | + xmove_fd(xopen(device, O_WRONLY), 3); |
| 43 | + write(3, &magic_value, 1); |
| 44 | + close(3); |
| 45 | + xmove_fd(xopen(device, O_WRONLY), 3); |
| 46 | +} |
| 47 | + |
| 48 | int watchdog_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| 49 | int watchdog_main(int argc, char **argv) |
| 50 | { |
| 51 | @@ -88,8 +106,7 @@ int watchdog_main(int argc, char **argv) |
| 52 | |
| 53 | bb_signals(BB_FATAL_SIGS, watchdog_shutdown); |
| 54 | |
| 55 | - /* Use known fd # - avoid needing global 'int fd' */ |
| 56 | - xmove_fd(xopen(argv[argc - 1], O_WRONLY), 3); |
| 57 | + watchdog_open(argv[argc - 1]); |
| 58 | |
| 59 | /* WDIOC_SETTIMEOUT takes seconds, not milliseconds */ |
| 60 | htimer_duration = htimer_duration / 1000; |
| 61 | -- |
| 62 | 2.11.0 |
| 63 | |