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 <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_INFINITY;
  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_INFINITY)
  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                         return log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
  49         } else {
  50                 int sec, flags;
  51                 char buf[FORMAT_TIMESPAN_MAX];
  52
  53                 sec = (int) ((watchdog_timeout + USEC_PER_SEC - 1) / USEC_PER_SEC);
  54                 r = ioctl(watchdog_fd, WDIOC_SETTIMEOUT, &sec);
  55                 if (r < 0)
  56                         return log_warning_errno(errno, "Failed to set timeout to %is: %m", sec);
  57
  58                 watchdog_timeout = (usec_t) sec * USEC_PER_SEC;
  59                 log_info("Set hardware watchdog to %s.", format_timespan(buf, sizeof(buf), watchdog_timeout, 0));
  60
  61                 flags = WDIOS_ENABLECARD;
  62                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
  63                 if (r < 0) {
  64                         /* ENOTTY means the watchdog is always enabled so we're fine */
  65                         log_full(errno == ENOTTY ? LOG_DEBUG : LOG_WARNING,
  66                                  "Failed to enable hardware watchdog: %m");
  67                         if (errno != ENOTTY)
  68                                 return -errno;
  69                 }
  70
  71                 r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
  72                 if (r < 0)
  73                         return log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
  74         }
  75
  76         return 0;
  77 }
  78
  79 static int open_watchdog(void) {
  80         struct watchdog_info ident;
  81
  82         if (watchdog_fd >= 0)
  83                 return 0;
  84
  85         watchdog_fd = open("/dev/watchdog", O_WRONLY|O_CLOEXEC);
  86         if (watchdog_fd < 0)
  87                 return -errno;
  88
  89         if (ioctl(watchdog_fd, WDIOC_GETSUPPORT, &ident) >= 0)
  90                 log_info("Hardware watchdog '%s', version %x",
  91                          ident.identity,
  92                          ident.firmware_version);
  93
  94         return update_timeout();
  95 }
  96
  97 int watchdog_set_timeout(usec_t *usec) {
  98         int r;
  99
 100         watchdog_timeout = *usec;
 101
 102         /* If we didn't open the watchdog yet and didn't get any
 103          * explicit timeout value set, don't do anything */
 104         if (watchdog_fd < 0 && watchdog_timeout == USEC_INFINITY)
 105                 return 0;
 106
 107         if (watchdog_fd < 0)
 108                 r = open_watchdog();
 109         else
 110                 r = update_timeout();
 111
 112         *usec = watchdog_timeout;
 113
 114         return r;
 115 }
 116
 117 int watchdog_ping(void) {
 118         int r;
 119
 120         if (watchdog_fd < 0) {
 121                 r = open_watchdog();
 122                 if (r < 0)
 123                         return r;
 124         }
 125
 126         r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
 127         if (r < 0)
 128                 return log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
 129
 130         return 0;
 131 }
 132
 133 void watchdog_close(bool disarm) {
 134         int r;
 135
 136         if (watchdog_fd < 0)
 137                 return;
 138
 139         if (disarm) {
 140                 int flags;
 141
 142                 /* Explicitly disarm it */
 143                 flags = WDIOS_DISABLECARD;
 144                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
 145                 if (r < 0)
 146                         log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
 147
 148                 /* To be sure, use magic close logic, too */
 149                 for (;;) {
 150                         static const char v = 'V';
 151
 152                         if (write(watchdog_fd, &v, 1) > 0)
 153                                 break;
 154
 155                         if (errno != EINTR) {
 156                                 log_error_errno(errno, "Failed to disarm watchdog timer: %m");
 157                                 break;
 158                         }
 159                 }
 160         }
 161
 162         watchdog_fd = safe_close(watchdog_fd);
 163 }