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https://github.com/projectacrn/acrn-hypervisor.git
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64d9c59aa1
There is one race issue between mevent callback (which is called in mevent_dispatch thread) and mevent_delete (which could be called in dev thread). And the callback is called after mevent_delete. libevent have the exactly same issue. The issue is decripted here: https://github.com/libevent/libevent/blob/master/whatsnew-2.1.txt The fixing is: We introduce a teardown callback to mevent and make sure there is no race issue between callback and teardown call. This patch updates the mevent API and the caller as well. Tracked-On: #1877 Signed-off-by: Yin Fengwei <fengwei.yin@intel.com> Acked-by: Yu Wang <yu1.wang@intel.com>
123 lines
2.6 KiB
C
123 lines
2.6 KiB
C
/*
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* Copyright (C) <2018> Intel Corporation
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <stdio.h>
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#include <stdbool.h>
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#include <unistd.h>
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#include <sys/timerfd.h>
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#include "vmmapi.h"
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#include "mevent.h"
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#include "timer.h"
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/* We can use timerfd and epoll mechanism to emulate kinds of timers like
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* PIT/RTC/WDT/PMTIMER/... in device model under Linux.
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* Compare with sigevent mechanism, timerfd has a advantage that it could
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* avoid race condition on resource accessing in the async sigev thread.
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*
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* Please note timerfd and epoll are all Linux specific. If the code need to be
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* ported to other OS, we can modify the api with POSIX timers and sigevent
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* mechanism.
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*/
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static void
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timer_handler(int fd __attribute__((unused)),
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enum ev_type t __attribute__((unused)),
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void *arg)
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{
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struct acrn_timer *timer = arg;
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uint64_t buf;
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int32_t size;
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if (timer == NULL) {
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return;
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}
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/* Consume I/O event for default EPOLLLT type.
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* Here is a temporary solution, the processing could be moved to
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* mevent.c once EVF_TIMER is supported.
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*/
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size = read(timer->fd, &buf, sizeof(buf));
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if (size < 1) {
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fprintf(stderr, "acrn_timer read timerfd error!");
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return;
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}
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if (timer->callback != NULL) {
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(*timer->callback)(timer->callback_param);
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}
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}
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int32_t
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acrn_timer_init(struct acrn_timer *timer, void (*cb)(void *), void *param)
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{
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if ((timer == NULL) || (cb == NULL)) {
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return -1;
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}
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timer->fd = -1;
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if ((timer->clockid == CLOCK_REALTIME) ||
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(timer->clockid == CLOCK_MONOTONIC)) {
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timer->fd = timerfd_create(timer->clockid,
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TFD_NONBLOCK | TFD_CLOEXEC);
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} else {
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perror("acrn_timer clockid is not supported.\n");
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}
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if (timer->fd <= 0) {
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perror("acrn_timer create failed.\n");
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return -1;
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}
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timer->mevp = mevent_add(timer->fd, EVF_READ, timer_handler, timer, NULL, NULL);
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if (timer->mevp == NULL) {
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close(timer->fd);
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perror("acrn_timer mevent add failed.\n");
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return -1;
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}
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timer->callback = cb;
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timer->callback_param = param;
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return 0;
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}
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void
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acrn_timer_deinit(struct acrn_timer *timer)
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{
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if (timer == NULL) {
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return;
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}
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if (timer->mevp != NULL) {
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mevent_delete_close(timer->mevp);
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timer->mevp = NULL;
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}
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timer->fd = -1;
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timer->callback = NULL;
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timer->callback_param = NULL;
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}
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int32_t
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acrn_timer_settime(struct acrn_timer *timer, struct itimerspec *new_value)
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{
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if (timer == NULL) {
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return -1;
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}
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return timerfd_settime(timer->fd, 0, new_value, NULL);
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}
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int32_t
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acrn_timer_gettime(struct acrn_timer *timer, struct itimerspec *cur_value)
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{
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if (timer == NULL) {
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return -1;
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}
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return timerfd_gettime(timer->fd, cur_value);
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}
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