src/shared/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 <errno.h>
  23 #include <fcntl.h>
  24 #include <sys/ioctl.h>
  25 #include <syslog.h>
  26 #include <unistd.h>
  27 #include <linux/watchdog.h>
  28
  29 #include "fd-util.h"
  30 #include "log.h"
  31 #include "time-util.h"
  32 #include "watchdog.h"
  33
  34 static int watchdog_fd = -1;
  35 static usec_t watchdog_timeout = USEC_INFINITY;
  36
  37 static int update_timeout(void) {
  38         int r;
  39
  40         if (watchdog_fd < 0)
  41                 return 0;
  42
  43         if (watchdog_timeout == USEC_INFINITY)
  44                 return 0;
  45         else if (watchdog_timeout == 0) {
  46                 int flags;
  47
  48                 flags = WDIOS_DISABLECARD;
  49                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
  50                 if (r < 0)
  51                         return log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
  52         } else {
  53                 int sec, flags;
  54                 char buf[FORMAT_TIMESPAN_MAX];
  55
  56                 sec = (int) ((watchdog_timeout + USEC_PER_SEC - 1) / USEC_PER_SEC);
  57                 r = ioctl(watchdog_fd, WDIOC_SETTIMEOUT, &sec);
  58                 if (r < 0)
  59                         return log_warning_errno(errno, "Failed to set timeout to %is: %m", sec);
  60
  61                 watchdog_timeout = (usec_t) sec * USEC_PER_SEC;
  62                 log_info("Set hardware watchdog to %s.", format_timespan(buf, sizeof(buf), watchdog_timeout, 0));
  63
  64                 flags = WDIOS_ENABLECARD;
  65                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
  66                 if (r < 0) {
  67                         /* ENOTTY means the watchdog is always enabled so we're fine */
  68                         log_full(errno == ENOTTY ? LOG_DEBUG : LOG_WARNING,
  69                                  "Failed to enable hardware watchdog: %m");
  70                         if (errno != ENOTTY)
  71                                 return -errno;
  72                 }
  73
  74                 r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
  75                 if (r < 0)
  76                         return log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
  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_INFINITY)
 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                 return log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
 132
 133         return 0;
 134 }
 135
 136 void watchdog_close(bool disarm) {
 137         int r;
 138
 139         if (watchdog_fd < 0)
 140                 return;
 141
 142         if (disarm) {
 143                 int flags;
 144
 145                 /* Explicitly disarm it */
 146                 flags = WDIOS_DISABLECARD;
 147                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
 148                 if (r < 0)
 149                         log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
 150
 151                 /* To be sure, use magic close logic, too */
 152                 for (;;) {
 153                         static const char v = 'V';
 154
 155                         if (write(watchdog_fd, &v, 1) > 0)
 156                                 break;
 157
 158                         if (errno != EINTR) {
 159                                 log_error_errno(errno, "Failed to disarm watchdog timer: %m");
 160                                 break;
 161                         }
 162                 }
 163         }
 164
 165         watchdog_fd = safe_close(watchdog_fd);
 166 }