procd/watchdog.c

/*
 * Copyright (C) 2013 Felix Fietkau <nbd@openwrt.org>
 * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/watchdog.h>

#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <unistd.h>

#include <libubox/uloop.h>

#include "procd.h"
#include "watchdog.h"

#define WDT_PATH	"/dev/watchdog"

static struct uloop_timeout wdt_timeout;
static int wdt_fd = -1;
static int wdt_drv_timeout = 30;
static int wdt_frequency = 5;
static bool wdt_magicclose = false;

void watchdog_ping(void)
{
	DEBUG(4, "Ping\n");
	if (wdt_fd >= 0 && write(wdt_fd, "X", 1) < 0)
		ERROR("WDT failed to write: %m\n");
}

static void watchdog_timeout_cb(struct uloop_timeout *t)
{
	watchdog_ping();
	uloop_timeout_set(t, wdt_frequency * 1000);
}

static int watchdog_open(bool cloexec)
{
	char *env = getenv("WDTFD");

	if (wdt_fd >= 0)
		return wdt_fd;

	if (env) {
		DEBUG(2, "Watchdog handover: fd=%s\n", env);
		wdt_fd = atoi(env);
		unsetenv("WDTFD");
	} else {
		wdt_fd = open(WDT_PATH, O_WRONLY);
	}

	if (wdt_fd < 0)
		return wdt_fd;

	if (cloexec)
		fcntl(wdt_fd, F_SETFD, fcntl(wdt_fd, F_GETFD) | FD_CLOEXEC);

	return wdt_fd;
}

static void watchdog_close(void)
{
	if (wdt_fd < 0)
		return;

	if (write(wdt_fd, "V", 1) < 0)
		ERROR("WDT failed to write release: %m\n");

	if (close(wdt_fd) == -1)
		ERROR("WDT failed to close watchdog: %m\n");

	wdt_fd = -1;
}

static int watchdog_set_drv_timeout(void)
{
	if (wdt_fd < 0)
		return -1;

	return ioctl(wdt_fd, WDIOC_SETTIMEOUT, &wdt_drv_timeout);
}

void watchdog_set_magicclose(bool val)
{
	wdt_magicclose = val;
}

bool watchdog_get_magicclose(void)
{
	return wdt_magicclose;
}

void watchdog_set_stopped(bool val)
{
	if (val) {
		uloop_timeout_cancel(&wdt_timeout);

		if (wdt_magicclose)
			watchdog_close();
	}
	else {
		watchdog_open(true);
		watchdog_set_drv_timeout();
		watchdog_timeout_cb(&wdt_timeout);
	}
}

bool watchdog_get_stopped(void)
{
	return !wdt_timeout.pending;
}

int watchdog_timeout(int timeout)
{
	if (timeout) {
		DEBUG(4, "Set watchdog timeout: %ds\n", timeout);
		wdt_drv_timeout = timeout;

		if (wdt_fd >= 0)
			watchdog_set_drv_timeout();
	}

	return wdt_drv_timeout;
}

int watchdog_frequency(int frequency)
{
	if (frequency) {
		DEBUG(4, "Set watchdog frequency: %ds\n", frequency);
		wdt_frequency = frequency;
	}

	return wdt_frequency;
}

char* watchdog_fd(void)
{
	static char fd_buf[12];

	if (wdt_fd < 0)
		return NULL;

	snprintf(fd_buf, sizeof(fd_buf), "%d", wdt_fd);

	return fd_buf;
}

void watchdog_init(int preinit)
{
	wdt_timeout.cb = watchdog_timeout_cb;

	if (watchdog_open(!preinit) < 0)
		return;

	LOG("- watchdog -\n");
	watchdog_set_drv_timeout();
	watchdog_timeout_cb(&wdt_timeout);

	DEBUG(4, "Opened watchdog with timeout %ds\n", watchdog_timeout(0));
}


void watchdog_set_cloexec(bool val)
{
	if (wdt_fd < 0)
		return;

	int flags = fcntl(wdt_fd, F_GETFD);
	if (val)
		flags |= FD_CLOEXEC;
	else
		flags &= ~FD_CLOEXEC;
	fcntl(wdt_fd, F_SETFD,  flags);
}