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/*
* This illustrates the bug where the cleanup function
* of a thread may be called too many times.
*
* main thread:
* - grab mutex
* - spawn thread1
* - go to sleep
* thread1:
* - register cleanup handler via pthread_cleanup_push()
* - try to grab mutex and sleep
* main:
* - kill thread1
* - go to sleep
* thread1 cleanup handler:
* - try to grab mutex and sleep
* main:
* - kill thread1
* - go to sleep
* thread1 cleanup handler:
* - wrongly called again
*/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <assert.h>
#include <unistd.h>
#define warn(fmt, args...) fprintf(stderr, "[%p] " fmt, (void*)pthread_self(), ## args)
#define warnf(fmt, args...) warn("%s:%i: " fmt, __FUNCTION__, __LINE__, ## args)
int ok_to_kill_thread;
static void thread_killed(void *arg);
static void *KillMeThread(void *thread_par)
{
pthread_t pthread_id;
warnf("Starting child thread\n");
pthread_id = pthread_self();
pthread_cleanup_push(thread_killed, (void *)pthread_id);
pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
/* main code */
warnf("please kill me now\n");
while (1) {
ok_to_kill_thread = 1;
sleep(1);
}
pthread_cleanup_pop(0);
return 0;
}
static void thread_killed(void *arg)
{
static int num_times_called = 0;
warnf("killing %p [cnt=%i]\n", arg, ++num_times_called);
assert(num_times_called == 1);
/* pick any cancellation endpoint, sleep() will do just fine */
while (1) {
warnf("sleeping in cancellation endpoint ...\n");
sleep(1);
}
warnf("done cleaning up\n");
}
int main(int argc, char *argv[])
{
int count = 3;
pthread_t app_pthread_id;
/* need to tweak this test a bit to play nice with signals and LT */
return 0;
ok_to_kill_thread = 0;
pthread_create(&app_pthread_id, NULL, KillMeThread, NULL);
warnf("waiting for thread to prepare itself\n");
while (!ok_to_kill_thread)
sleep(1);
while (count--) {
warnf("killing thread\n");
pthread_cancel(app_pthread_id);
sleep(3);
}
return 0;
}
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