mirror of https://gerrit.osmocom.org/libosmocore
300 lines
8.1 KiB
C
300 lines
8.1 KiB
C
/*
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* (C) 2008,2009 by Holger Hans Peter Freyther <zecke@selfish.org>
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* (C) 2011 by Harald Welte <laforge@gnumonks.org>
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* All Rights Reserved
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*
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* Authors: Holger Hans Peter Freyther <zecke@selfish.org>
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* Harald Welte <laforge@gnumonks.org>
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* Pablo Neira Ayuso <pablo@gnumonks.org>
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*
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* SPDX-License-Identifier: GPL-2.0+
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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/*! \addtogroup timer
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* @{
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* Osmocom timer abstraction; modelled after linux kernel timers
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*
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* \file timer.c */
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#include <assert.h>
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#include <string.h>
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#include <limits.h>
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#include <osmocom/core/timer.h>
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#include <osmocom/core/timer_compat.h>
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#include <osmocom/core/linuxlist.h>
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/* These store the amount of time that we wait until next timer expires. */
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static __thread struct timeval nearest;
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static __thread struct timeval *nearest_p;
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static __thread struct rb_root timer_root = RB_ROOT;
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static void __add_timer(struct osmo_timer_list *timer)
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{
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struct rb_node **new = &(timer_root.rb_node);
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struct rb_node *parent = NULL;
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while (*new) {
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struct osmo_timer_list *this;
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this = container_of(*new, struct osmo_timer_list, node);
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parent = *new;
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if (timercmp(&timer->timeout, &this->timeout, <))
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new = &((*new)->rb_left);
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else
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new = &((*new)->rb_right);
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}
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rb_link_node(&timer->node, parent, new);
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rb_insert_color(&timer->node, &timer_root);
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}
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/*! set up timer callback and data
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* \param[in] timer the timer that should be added
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* \param[in] cb function to be called when timer expires
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* \param[in] data pointer to data that passed to the callback function
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*/
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void osmo_timer_setup(struct osmo_timer_list *timer, void (*cb)(void *data),
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void *data)
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{
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timer->cb = cb;
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timer->data = data;
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}
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/*! add a new timer to the timer management
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* \param[in] timer the timer that should be added
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*/
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void osmo_timer_add(struct osmo_timer_list *timer)
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{
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osmo_timer_del(timer);
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timer->active = 1;
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INIT_LLIST_HEAD(&timer->list);
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__add_timer(timer);
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}
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/*! schedule a timer at a given future relative time
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* \param[in] timer the to-be-added timer
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* \param[in] seconds number of seconds from now
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* \param[in] microseconds number of microseconds from now
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*
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* This function can be used to (re-)schedule a given timer at a
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* specified number of seconds+microseconds in the future. It will
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* internally add it to the timer management data structures, thus
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* osmo_timer_add() is automatically called.
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*/
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void
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osmo_timer_schedule(struct osmo_timer_list *timer, int seconds, int microseconds)
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{
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struct timeval current_time;
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osmo_gettimeofday(¤t_time, NULL);
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timer->timeout.tv_sec = seconds;
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timer->timeout.tv_usec = microseconds;
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timeradd(&timer->timeout, ¤t_time, &timer->timeout);
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osmo_timer_add(timer);
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}
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/*! delete a timer from timer management
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* \param[in] timer the to-be-deleted timer
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*
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* This function can be used to delete a previously added/scheduled
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* timer from the timer management code.
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*/
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void osmo_timer_del(struct osmo_timer_list *timer)
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{
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if (timer->active) {
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timer->active = 0;
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rb_erase(&timer->node, &timer_root);
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/* make sure this is not already scheduled for removal. */
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if (!llist_empty(&timer->list))
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llist_del_init(&timer->list);
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}
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}
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/*! check if given timer is still pending
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* \param[in] timer the to-be-checked timer
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* \return 1 if pending, 0 otherwise
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*
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* This function can be used to determine whether a given timer
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* has alredy expired (returns 0) or is still pending (returns 1)
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*/
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int osmo_timer_pending(const struct osmo_timer_list *timer)
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{
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return timer->active;
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}
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/*! compute the remaining time of a timer
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* \param[in] timer the to-be-checked timer
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* \param[in] now the current time (NULL if not known)
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* \param[out] remaining remaining time until timer fires
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* \return 0 if timer has not expired yet, -1 if it has
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*
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* This function can be used to determine the amount of time
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* remaining until the expiration of the timer.
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*/
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int osmo_timer_remaining(const struct osmo_timer_list *timer,
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const struct timeval *now,
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struct timeval *remaining)
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{
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struct timeval current_time;
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if (!now)
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osmo_gettimeofday(¤t_time, NULL);
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else
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current_time = *now;
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timersub(&timer->timeout, ¤t_time, remaining);
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if (remaining->tv_sec < 0)
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return -1;
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return 0;
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}
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/*! Determine time between now and the nearest timer
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* \returns pointer to timeval of nearest timer, NULL if there is none
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*
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* if we have a nearest time return the delta between the current
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* time and the time of the nearest timer.
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* If the nearest timer timed out return NULL and then we will
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* dispatch everything after the select
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*/
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struct timeval *osmo_timers_nearest(void)
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{
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/* nearest_p is exactly what we need already: NULL if nothing is
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* waiting, {0,0} if we must dispatch immediately, and the correct
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* delay if we need to wait */
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return nearest_p;
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}
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/*! Determine time between now and the nearest timer in milliseconds
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* \returns number of milliseconds until nearest timer expires; -1 if no timers pending
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*/
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int osmo_timers_nearest_ms(void)
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{
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int nearest_ms;
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if (!nearest_p)
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return -1;
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nearest_ms = nearest_p->tv_sec * 1000;
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#ifndef EMBEDDED
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/* By adding 999 milliseconds, we ensure rounding up to the nearest
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* whole millisecond. This approach prevents the return of 0 when the
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* timer is still active, and it guarantees that the calling process
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* does not wait for a duration shorter than the time remaining on the
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* timer. */
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nearest_ms += (nearest_p->tv_usec + 999) / 1000;
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#else
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nearest_ms += nearest_p->tv_usec / 1000;
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#endif
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return nearest_ms;
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}
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static void update_nearest(struct timeval *cand, struct timeval *current)
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{
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if (cand->tv_sec != LONG_MAX) {
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if (timercmp(cand, current, >))
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timersub(cand, current, &nearest);
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else {
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/* loop again inmediately */
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timerclear(&nearest);
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}
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nearest_p = &nearest;
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} else {
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nearest_p = NULL;
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}
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}
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/*! Find the nearest time and update nearest_p */
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void osmo_timers_prepare(void)
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{
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struct rb_node *node;
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struct timeval current;
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osmo_gettimeofday(¤t, NULL);
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node = rb_first(&timer_root);
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if (node) {
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struct osmo_timer_list *this;
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this = container_of(node, struct osmo_timer_list, node);
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update_nearest(&this->timeout, ¤t);
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} else {
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nearest_p = NULL;
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}
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}
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/*! fire all timers... and remove them */
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int osmo_timers_update(void)
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{
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struct timeval current_time;
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struct rb_node *node;
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struct llist_head timer_eviction_list;
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struct osmo_timer_list *this;
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int work = 0;
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osmo_gettimeofday(¤t_time, NULL);
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INIT_LLIST_HEAD(&timer_eviction_list);
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for (node = rb_first(&timer_root); node; node = rb_next(node)) {
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this = container_of(node, struct osmo_timer_list, node);
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if (timercmp(&this->timeout, ¤t_time, >))
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break;
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llist_add(&this->list, &timer_eviction_list);
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}
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/*
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* The callbacks might mess with our list and in this case
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* even llist_for_each_entry_safe is not safe to use. To allow
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* osmo_timer_del to be called from within the callback we need
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* to restart the iteration for each element scheduled for removal.
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*
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* The problematic scenario is the following: Given two timers A
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* and B that have expired at the same time. Thus, they are both
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* in the eviction list in this order: A, then B. If we remove
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* timer B from the A's callback, we continue with B in the next
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* iteration step, leading to an access-after-release.
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*/
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restart:
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llist_for_each_entry(this, &timer_eviction_list, list) {
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osmo_timer_del(this);
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if (this->cb)
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this->cb(this->data);
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work = 1;
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goto restart;
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}
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return work;
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}
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/*! Check how many timers we have in the system
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* \returns number of \ref osmo_timer_list registered */
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int osmo_timers_check(void)
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{
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struct rb_node *node;
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int i = 0;
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for (node = rb_first(&timer_root); node; node = rb_next(node)) {
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i++;
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}
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return i;
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}
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/*! @} */
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