/*
 * Copyright (C) 2013-2020 Canonical, Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * This code is a complete clean re-write of the stress tool by
 * Colin Ian King <colin.king@canonical.com> and attempts to be
 * backwardly compatible with the stress tool by Amos Waterland
 * <apw@rossby.metr.ou.edu> but has more stress tests and more
 * functionality.
 *
 */
#include "stress-ng.h"

typedef struct {
	char *name;
	bool timeout;
} stress_mem_info_t;

static const stress_help_t help[] = {
	{ NULL,	"memhotplug N",	"start N workers that exercise memory hotplug" },
	{ NULL,	"memhotplug-ops N",	"stop after N memory hotplug operations" },
	{ NULL,	NULL,		NULL }
};

#if defined(__linux__)
static const char sys_memory_path[] = "/sys/devices/system/memory";

/*
 *  stress_memhotplug_supported()
 *      check if we can run this as root
 */
static int stress_memhotplug_supported(const char *name)
{
	if (!stress_check_capability(SHIM_CAP_SYS_ADMIN)) {
		pr_inf("%s stressor will be skipped, "
			"need to be running with CAP_SYS_ADMIN "
			"rights for this stressor\n", name);
		return -1;
	}
	return 0;
}

static void stress_itimer_handler(int sig)
{
	(void)sig;
}

static bool stress_memhotplug_removable(char *name)
{
	char path[PATH_MAX];
	char buf[64];
	int val;

	(void)snprintf(path, sizeof(path), "%s/%s/removable",
		sys_memory_path, name);
	if (system_read(path, buf, sizeof(buf)) < 0)
		return false;
	if (sscanf(buf, "%1d", &val) != 1)
		return false;
	if (val == 0)
		return false;
	return true;
}

static void stress_memhotplug_set_timer(const unsigned int secs)
{
	struct itimerval timer;

	(void)memset(&timer, 0, sizeof(timer));
	timer.it_value.tv_sec = secs;
	timer.it_value.tv_usec = 0;
	timer.it_interval.tv_sec = secs;
	timer.it_interval.tv_usec = 0;
	(void)setitimer(ITIMER_PROF, &timer, NULL);
}

static void stress_memhotplug_mem_toggle(stress_mem_info_t *mem_info)
{
	char path[PATH_MAX];
	int fd;
	ssize_t n;

	/*
	 *  Skip any hotplug memory regions that previously
	 *  timeout to avoid any repeated delays
	 */
	if (mem_info->timeout)
		return;

	if (!stress_memhotplug_removable(mem_info->name))
		return;

	(void)snprintf(path, sizeof(path), "%s/%s/state",
		sys_memory_path, mem_info->name);
	fd = open(path, O_RDWR | O_NONBLOCK);
	if (fd < 0)
		return;

	stress_memhotplug_set_timer(3);
	errno = 0;
	n = write(fd, "offline", 7);
	if (n < 0) {
		if (errno == EINTR)
			mem_info->timeout = true;
	}

	stress_memhotplug_set_timer(5);
	errno = 0;
	n = write(fd, "online", 6);
	(void)n;
	stress_memhotplug_set_timer(0);
	(void)close(fd);
}

static void stress_memhotplug_mem_online(stress_mem_info_t *mem_info)
{
	char path[PATH_MAX];
	int fd;
	ssize_t n;

	(void)snprintf(path, sizeof(path), "%s/%s/state",
		sys_memory_path, mem_info->name);
	fd = open(path, O_RDWR | O_NONBLOCK);
	if (fd < 0)
		return;

	stress_memhotplug_set_timer(5);
	errno = 0;
	n = write(fd, "online", 6);
	if (n < 0) {
		if (errno == EINTR)
			mem_info->timeout = true;
	}
	stress_memhotplug_set_timer(0);
	(void)close(fd);
}

/*
 *  stress_memhotplug()
 *	stress the linux memory hotplug subsystem
 */
static int stress_memhotplug(const stress_args_t *args)
{
	DIR *dir;
	struct dirent *d;
	stress_mem_info_t *mem_info;
	size_t i, n = 0, max;

	if (stress_sighandler(args->name, SIGPROF, stress_itimer_handler, NULL))
		return EXIT_NO_RESOURCE;

	dir = opendir(sys_memory_path);
	if (!dir) {
		pr_inf("%s: %s not accessible, skipping stressor\n",
			args->name, sys_memory_path);
		return EXIT_NOT_IMPLEMENTED;
	}

	/* Figure out number of potential hotplug memory regsions */
	while ((d = readdir(dir)) != NULL) {
		if ((strncmp(d->d_name, "memory", 6) == 0) &&
		     stress_memhotplug_removable(d->d_name))
			n++;
	}
	if (n == 0) {
		pr_inf("%s: no hotplug memory entries found, skipping stressor\n",
			args->name);
		(void)closedir(dir);
		return EXIT_NOT_IMPLEMENTED;
	}
	rewinddir(dir);

	mem_info = calloc(n, sizeof(*mem_info));
	if (!mem_info) {
		pr_inf("%s: out of memory\n", args->name);
		(void)closedir(dir);
		return EXIT_NO_RESOURCE;
	}

	max = 0;
	while ((max < n) && ((d = readdir(dir)) != NULL)) {
		if ((strncmp(d->d_name, "memory", 6) == 0) &&
		     stress_memhotplug_removable(d->d_name)) {
			mem_info[max].name = strdup(d->d_name);
			mem_info[max].timeout = false;
			max++;
		}
	}
	(void)closedir(dir);

	pr_dbg("%s: found %zd removable hotplug memory regions\n",
		args->name, max);

	do {
		bool ok = false;
		for (i = 0; keep_stressing() && (i < max); i++) {
			stress_memhotplug_mem_toggle(&mem_info[i]);
			if (!mem_info[i].timeout)
				ok |= true;
			inc_counter(args);
		}
		if (!ok) {
			for (i = 0; i < max; i++)
				stress_memhotplug_mem_online(&mem_info[i]);
		}
	} while (keep_stressing());

	for (i = 0; i < max; i++)
		stress_memhotplug_mem_online(&mem_info[i]);
	for (i = 0; i < n; i++)
		free(mem_info[i].name);
	free(mem_info);

	return EXIT_SUCCESS;
}

stressor_info_t stress_memhotplug_info = {
	.stressor = stress_memhotplug,
	.class = CLASS_OS,
	.supported = stress_memhotplug_supported,
	.help = help
};
#else
stressor_info_t stress_memhotplug_info = {
	.stressor = stress_not_implemented,
	.class = CLASS_OS,
	.help = help
};
#endif