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 <unistd.h>
  26 #include <linux/watchdog.h>
  27
  28 #include "fd-util.h"
  29 #include "log.h"
  30 #include "watchdog.h"
  31
  32 static int watchdog_fd = -1;
  33 static usec_t watchdog_timeout = USEC_INFINITY;
  34
  35 static int update_timeout(void) {
  36         int r;
  37
  38         if (watchdog_fd < 0)
  39                 return 0;
  40
  41         if (watchdog_timeout == USEC_INFINITY)
  42                 return 0;
  43         else if (watchdog_timeout == 0) {
  44                 int flags;
  45
  46                 flags = WDIOS_DISABLECARD;
  47                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
  48                 if (r < 0)
  49                         return log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
  50         } else {
  51                 int sec, flags;
  52                 char buf[FORMAT_TIMESPAN_MAX];
  53
  54                 sec = (int) ((watchdog_timeout + USEC_PER_SEC - 1) / USEC_PER_SEC);
  55                 r = ioctl(watchdog_fd, WDIOC_SETTIMEOUT, &sec);
  56                 if (r < 0)
  57                         return log_warning_errno(errno, "Failed to set timeout to %is: %m", sec);
  58
  59                 watchdog_timeout = (usec_t) sec * USEC_PER_SEC;
  60                 log_info("Set hardware watchdog to %s.", format_timespan(buf, sizeof(buf), watchdog_timeout, 0));
  61
  62                 flags = WDIOS_ENABLECARD;
  63                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
  64                 if (r < 0) {
  65                         /* ENOTTY means the watchdog is always enabled so we're fine */
  66                         log_full(errno == ENOTTY ? LOG_DEBUG : LOG_WARNING,
  67                                  "Failed to enable hardware watchdog: %m");
  68                         if (errno != ENOTTY)
  69                                 return -errno;
  70                 }
  71
  72                 r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
  73                 if (r < 0)
  74                         return log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
  75         }
  76
  77         return 0;
  78 }
  79
  80 static int open_watchdog(void) {
  81         struct watchdog_info ident;
  82
  83         if (watchdog_fd >= 0)
  84                 return 0;
  85
  86         watchdog_fd = open("/dev/watchdog", O_WRONLY|O_CLOEXEC);
  87         if (watchdog_fd < 0)
  88                 return -errno;
  89
  90         if (ioctl(watchdog_fd, WDIOC_GETSUPPORT, &ident) >= 0)
  91                 log_info("Hardware watchdog '%s', version %x",
  92                          ident.identity,
  93                          ident.firmware_version);
  94
  95         return update_timeout();
  96 }
  97
  98 int watchdog_set_timeout(usec_t *usec) {
  99         int r;
 100
 101         watchdog_timeout = *usec;
 102
 103         /* If we didn't open the watchdog yet and didn't get any
 104          * explicit timeout value set, don't do anything */
 105         if (watchdog_fd < 0 && watchdog_timeout == USEC_INFINITY)
 106                 return 0;
 107
 108         if (watchdog_fd < 0)
 109                 r = open_watchdog();
 110         else
 111                 r = update_timeout();
 112
 113         *usec = watchdog_timeout;
 114
 115         return r;
 116 }
 117
 118 int watchdog_ping(void) {
 119         int r;
 120
 121         if (watchdog_fd < 0) {
 122                 r = open_watchdog();
 123                 if (r < 0)
 124                         return r;
 125         }
 126
 127         r = ioctl(watchdog_fd, WDIOC_KEEPALIVE, 0);
 128         if (r < 0)
 129                 return log_warning_errno(errno, "Failed to ping hardware watchdog: %m");
 130
 131         return 0;
 132 }
 133
 134 void watchdog_close(bool disarm) {
 135         int r;
 136
 137         if (watchdog_fd < 0)
 138                 return;
 139
 140         if (disarm) {
 141                 int flags;
 142
 143                 /* Explicitly disarm it */
 144                 flags = WDIOS_DISABLECARD;
 145                 r = ioctl(watchdog_fd, WDIOC_SETOPTIONS, &flags);
 146                 if (r < 0)
 147                         log_warning_errno(errno, "Failed to disable hardware watchdog: %m");
 148
 149                 /* To be sure, use magic close logic, too */
 150                 for (;;) {
 151                         static const char v = 'V';
 152
 153                         if (write(watchdog_fd, &v, 1) > 0)
 154                                 break;
 155
 156                         if (errno != EINTR) {
 157                                 log_error_errno(errno, "Failed to disarm watchdog timer: %m");
 158                                 break;
 159                         }
 160                 }
 161         }
 162
 163         watchdog_fd = safe_close(watchdog_fd);
 164 }