cregit-Linux how code gets into the kernel

Release 4.10 tools/testing/selftests/futex/functional/futex_wait_uninitialized_heap.c

/******************************************************************************
 *
 * Copyright FUJITSU LIMITED 2010
 * Copyright KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
 *
 *   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.
 *
 * DESCRIPTION
 *      Wait on uninitialized heap. It shold be zero and FUTEX_WAIT should
 *      return immediately. This test is intent to test zero page handling in
 *      futex.
 *
 * AUTHOR
 *      KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
 *
 * HISTORY
 *      2010-Jan-6: Initial version by KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
 *
 *****************************************************************************/

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <syscall.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include <linux/futex.h>
#include <libgen.h>

#include "logging.h"
#include "futextest.h"


#define WAIT_US 5000000


static int child_blocked = 1;

static int child_ret;

void *buf;


void usage(char *prog) { printf("Usage: %s\n", prog); printf(" -c Use color\n"); printf(" -h Display this help message\n"); printf(" -v L Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n", VQUIET, VCRITICAL, VINFO); }

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void *wait_thread(void *arg) { int res; child_ret = RET_PASS; res = futex_wait(buf, 1, NULL, 0); child_blocked = 0; if (res != 0 && errno != EWOULDBLOCK) { error("futex failure\n", errno); child_ret = RET_ERROR; } pthread_exit(NULL); }

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int main(int argc, char **argv) { int c, ret = RET_PASS; long page_size; pthread_t thr; while ((c = getopt(argc, argv, "chv:")) != -1) { switch (c) { case 'c': log_color(1); break; case 'h': usage(basename(argv[0])); exit(0); case 'v': log_verbosity(atoi(optarg)); break; default: usage(basename(argv[0])); exit(1); } } page_size = sysconf(_SC_PAGESIZE); buf = mmap(NULL, page_size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0); if (buf == (void *)-1) { error("mmap\n", errno); exit(1); } printf("%s: Test the uninitialized futex value in FUTEX_WAIT\n", basename(argv[0])); ret = pthread_create(&thr, NULL, wait_thread, NULL); if (ret) { error("pthread_create\n", errno); ret = RET_ERROR; goto out; } info("waiting %dus for child to return\n", WAIT_US); usleep(WAIT_US); ret = child_ret; if (child_blocked) { fail("child blocked in kernel\n"); ret = RET_FAIL; } out: print_result(ret); return ret; }

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