src/watchdog.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2012 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <sys/ioctl.h>
  23 #include <errno.h>
  24 #include <fcntl.h>
  25 #include <unistd.h>
  26 #include <linux/watchdog.h>
  27
  28 #include "watchdog.h"
  29 #include "log.h"
  30
  31 static int watchdog_fd = -1;
  32 static usec_t watchdog_timeout = (usec_t) -1;
  33
  34 static int update_timeout(void) {
  35         int r;
  36
  37         if (watchdog_fd < 0)
  38                 return 0;
  39
  40         if (watchdog_timeout == (usec_t) -1)
  41                 return 0;
  42         else if (watchdog_timeout == 0) {
  43                 int flags;
  44
  45                 flags = WDIOS_DISABLECARD;
  46                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
  47                 if (r < 0) {
  48                         log_warning("Failed to disable hardware watchdog: %m");
  49                         return -errno;
  50                 }
  51         } else {
  52                 int sec, flags;
  53                 char buf[FORMAT_TIMESPAN_MAX];
  54
  55                 sec = (int) ((watchdog_timeout + USEC_PER_SEC - 1) / USEC_PER_SEC);
  56                 r = ioctl(watchdog_fd, WDIOC_SETTIMEOUT, &sec);
  57                 if (r < 0) {
  58                         log_warning("Failed to set timeout to %is: %m", sec);
  59                         return -errno;
  60                 }
  61
  62                 watchdog_timeout = (usec_t) sec * USEC_PER_SEC;
  63                 log_info("Set hardware watchdog to %s.", format_timespan(buf, sizeof(buf), watchdog_timeout));
  64
  65                 flags = WDIOS_ENABLECARD;
  66                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
  67                 if (r < 0) {
  68                         log_warning("Failed to enable hardware watchdog: %m");
  69                         return -errno;
  70                 }
  71
  72                 r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
  73                 if (r < 0) {
  74                         log_warning("Failed to ping hardware watchdog: %m");
  75                         return -errno;
  76                 }
  77         }
  78
  79         return 0;
  80 }
  81
  82 static int open_watchdog(void) {
  83         struct watchdog_info ident;
  84
  85         if (watchdog_fd >= 0)
  86                 return 0;
  87
  88         watchdog_fd = open("/dev/watchdog", O_WRONLY|O_CLOEXEC);
  89         if (watchdog_fd < 0)
  90                 return -errno;
  91
  92         if (ioctl(watchdog_fd, WDIOC_GETSUPPORT, &ident) >= 0)
  93                 log_info("Hardware watchdog '%s', version %x",
  94                          ident.identity,
  95                          ident.firmware_version);
  96
  97         return update_timeout();
  98 }
  99
 100 int watchdog_set_timeout(usec_t *usec) {
 101         int r;
 102
 103         watchdog_timeout = *usec;
 104
 105         /* If we didn't open the watchdog yet and didn't get any
 106          * explicit timeout value set, don't do anything */
 107         if (watchdog_fd < 0 && watchdog_timeout == (usec_t) -1)
 108                 return 0;
 109
 110         if (watchdog_fd < 0)
 111                 r = open_watchdog();
 112         else
 113                 r = update_timeout();
 114
 115         *usec = watchdog_timeout;
 116
 117         return r;
 118 }
 119
 120 int watchdog_ping(void) {
 121         int r;
 122
 123         if (watchdog_fd < 0) {
 124                 r = open_watchdog();
 125                 if (r < 0)
 126                         return r;
 127         }
 128
 129         r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
 130         if (r < 0) {
 131                 log_warning("Failed to ping hardware watchdog: %m");
 132                 return -errno;
 133         }
 134
 135         return 0;
 136 }
 137
 138 void watchdog_close(bool disarm) {
 139         int r;
 140
 141         if (watchdog_fd < 0)
 142                 return;
 143
 144         if (disarm) {
 145                 int flags;
 146
 147                 /* Explicitly disarm it */
 148                 flags = WDIOS_DISABLECARD;
 149                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
 150                 if (r < 0)
 151                         log_warning("Failed to disable hardware watchdog: %m");
 152
 153                 /* To be sure, use magic close logic, too */
 154                 for (;;) {
 155                         static const char v = 'V';
 156
 157                         if (write(watchdog_fd, &v, 1) > 0)
 158                                 break;
 159
 160                         if (errno != EINTR) {
 161                                 log_error("Failed to disarm watchdog timer: %m");
 162                                 break;
 163                         }
 164                 }
 165         }
 166
 167         close_nointr_nofail(watchdog_fd);
 168         watchdog_fd = -1;
 169 }