xref: /dpdk/lib/eal/linux/eal_alarm.c (revision a4835c22ccfb5c5ba0aa5b32ebbafc0df12bf75a)

/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 2010-2014 Intel Corporation
 */
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <errno.h>
#include <pthread.h>
#include <sys/queue.h>
#include <sys/time.h>
#include <sys/timerfd.h>

#include <eal_trace_internal.h>
#include <rte_interrupts.h>
#include <rte_alarm.h>
#include <rte_common.h>
#include <rte_errno.h>
#include <rte_spinlock.h>

#include <eal_private.h>

#ifndef	TFD_NONBLOCK
#include <fcntl.h>
#define	TFD_NONBLOCK	O_NONBLOCK
#endif

#define NS_PER_US 1000
#define US_PER_MS 1000
#define MS_PER_S 1000
#ifndef US_PER_S
#define US_PER_S (US_PER_MS * MS_PER_S)
#endif

#ifdef CLOCK_MONOTONIC_RAW /* Defined in glibc bits/time.h */
#define CLOCK_TYPE_ID CLOCK_MONOTONIC_RAW
#else
#define CLOCK_TYPE_ID CLOCK_MONOTONIC
#endif

struct alarm_entry {
	LIST_ENTRY(alarm_entry) next;
	struct timeval time;
	rte_eal_alarm_callback cb_fn;
	void *cb_arg;
	volatile uint8_t executing;
	volatile pthread_t executing_id;
};

static LIST_HEAD(alarm_list, alarm_entry) alarm_list = LIST_HEAD_INITIALIZER();
static rte_spinlock_t alarm_list_lk = RTE_SPINLOCK_INITIALIZER;

static struct rte_intr_handle *intr_handle;
static int handler_registered = 0;
static void eal_alarm_callback(void *arg);

void
rte_eal_alarm_cleanup(void)
{
	rte_intr_instance_free(intr_handle);
}

int
rte_eal_alarm_init(void)
{

	intr_handle = rte_intr_instance_alloc(RTE_INTR_INSTANCE_F_PRIVATE);
	if (intr_handle == NULL) {
		EAL_LOG(ERR, "Fail to allocate intr_handle");
		goto error;
	}

	if (rte_intr_type_set(intr_handle, RTE_INTR_HANDLE_ALARM))
		goto error;

	/* create a timerfd file descriptor */
	if (rte_intr_fd_set(intr_handle,
			timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK)))
		goto error;

	if (rte_intr_fd_get(intr_handle) == -1)
		goto error;
	return 0;

error:
	rte_intr_instance_free(intr_handle);
	rte_errno = errno;
	return -1;
}

static void
eal_alarm_callback(void *arg __rte_unused)
{
	struct timespec now;
	struct alarm_entry *ap;

	rte_spinlock_lock(&alarm_list_lk);
	while ((ap = LIST_FIRST(&alarm_list)) !=NULL &&
			clock_gettime(CLOCK_TYPE_ID, &now) == 0 &&
			(ap->time.tv_sec < now.tv_sec || (ap->time.tv_sec == now.tv_sec &&
						(ap->time.tv_usec * NS_PER_US) <= now.tv_nsec))) {
		ap->executing = 1;
		ap->executing_id = pthread_self();
		rte_spinlock_unlock(&alarm_list_lk);

		ap->cb_fn(ap->cb_arg);

		rte_spinlock_lock(&alarm_list_lk);

		LIST_REMOVE(ap, next);
		free(ap);
	}

	if (!LIST_EMPTY(&alarm_list)) {
		struct itimerspec atime = { .it_interval = { 0, 0 } };

		ap = LIST_FIRST(&alarm_list);
		atime.it_value.tv_sec = ap->time.tv_sec;
		atime.it_value.tv_nsec = ap->time.tv_usec * NS_PER_US;
		/* perform borrow for subtraction if necessary */
		if (now.tv_nsec > (ap->time.tv_usec * NS_PER_US))
			atime.it_value.tv_sec--, atime.it_value.tv_nsec += US_PER_S * NS_PER_US;

		atime.it_value.tv_sec -= now.tv_sec;
		atime.it_value.tv_nsec -= now.tv_nsec;
		timerfd_settime(rte_intr_fd_get(intr_handle), 0, &atime, NULL);
	}
	rte_spinlock_unlock(&alarm_list_lk);
}

int
rte_eal_alarm_set(uint64_t us, rte_eal_alarm_callback cb_fn, void *cb_arg)
{
	struct timespec now;
	int ret = 0;
	struct alarm_entry *ap, *new_alarm;

	/* Check parameters, including that us won't cause a uint64_t overflow */
	if (us < 1 || us > (UINT64_MAX - US_PER_S) || cb_fn == NULL)
		return -EINVAL;

	new_alarm = calloc(1, sizeof(*new_alarm));
	if (new_alarm == NULL)
		return -ENOMEM;

	/* use current time to calculate absolute time of alarm */
	clock_gettime(CLOCK_TYPE_ID, &now);

	new_alarm->cb_fn = cb_fn;
	new_alarm->cb_arg = cb_arg;
	new_alarm->time.tv_usec = ((now.tv_nsec / NS_PER_US) + us) % US_PER_S;
	new_alarm->time.tv_sec = now.tv_sec + (((now.tv_nsec / NS_PER_US) + us) / US_PER_S);

	rte_spinlock_lock(&alarm_list_lk);
	if (!handler_registered) {
		/* registration can fail, callback can be registered later */
		if (rte_intr_callback_register(intr_handle,
				eal_alarm_callback, NULL) == 0)
			handler_registered = 1;
	}

	if (LIST_EMPTY(&alarm_list))
		LIST_INSERT_HEAD(&alarm_list, new_alarm, next);
	else {
		LIST_FOREACH(ap, &alarm_list, next) {
			if (ap->time.tv_sec > new_alarm->time.tv_sec ||
					(ap->time.tv_sec == new_alarm->time.tv_sec &&
							ap->time.tv_usec > new_alarm->time.tv_usec)){
				LIST_INSERT_BEFORE(ap, new_alarm, next);
				break;
			}
			if (LIST_NEXT(ap, next) == NULL) {
				LIST_INSERT_AFTER(ap, new_alarm, next);
				break;
			}
		}
	}

	if (LIST_FIRST(&alarm_list) == new_alarm) {
		struct itimerspec alarm_time = {
			.it_interval = {0, 0},
			.it_value = {
				.tv_sec = us / US_PER_S,
				.tv_nsec = (us % US_PER_S) * NS_PER_US,
			},
		};
		ret |= timerfd_settime(rte_intr_fd_get(intr_handle), 0, &alarm_time, NULL);
	}
	rte_spinlock_unlock(&alarm_list_lk);

	rte_eal_trace_alarm_set(us, cb_fn, cb_arg, ret);
	return ret;
}

int
rte_eal_alarm_cancel(rte_eal_alarm_callback cb_fn, void *cb_arg)
{
	struct alarm_entry *ap, *ap_prev;
	int count = 0;
	int err = 0;
	int executing;

	if (!cb_fn) {
		rte_errno = EINVAL;
		return -1;
	}

	do {
		executing = 0;
		rte_spinlock_lock(&alarm_list_lk);
		/* remove any matches at the start of the list */
		while ((ap = LIST_FIRST(&alarm_list)) != NULL &&
				cb_fn == ap->cb_fn &&
				(cb_arg == (void *)-1 || cb_arg == ap->cb_arg)) {

			if (ap->executing == 0) {
				LIST_REMOVE(ap, next);
				free(ap);
				count++;
			} else {
				/* If calling from other context, mark that alarm is executing
				 * so loop can spin till it finish. Otherwise we are trying to
				 * cancel our self - mark it by EINPROGRESS */
				if (pthread_equal(ap->executing_id, pthread_self()) == 0)
					executing++;
				else
					err = EINPROGRESS;

				break;
			}
		}
		ap_prev = ap;

		/* now go through list, removing entries not at start */
		LIST_FOREACH(ap, &alarm_list, next) {
			/* this won't be true first time through */
			if (cb_fn == ap->cb_fn &&
					(cb_arg == (void *)-1 || cb_arg == ap->cb_arg)) {

				if (ap->executing == 0) {
					LIST_REMOVE(ap, next);
					free(ap);
					count++;
					ap = ap_prev;
				} else if (pthread_equal(ap->executing_id, pthread_self()) == 0)
					executing++;
				else
					err = EINPROGRESS;
			}
			ap_prev = ap;
		}

		rte_spinlock_unlock(&alarm_list_lk);

		/* Yield control to a second thread executing eal_alarm_callback to avoid
		 * its starvation, as it is waiting for the lock we have just released.
		 */
		sched_yield();
	} while (executing != 0);

	if (count == 0 && err == 0)
		rte_errno = ENOENT;
	else if (err)
		rte_errno = err;

	rte_eal_trace_alarm_cancel(cb_fn, cb_arg, count);
	return count;
}