cregit-Linux how code gets into the kernel

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

/******************************************************************************
 *
 *   Copyright © International Business Machines  Corp., 2009
 *
 *   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
 *      1. Block a thread using FUTEX_WAIT
 *      2. Attempt to use FUTEX_CMP_REQUEUE_PI on the futex from 1.
 *      3. The kernel must detect the mismatch and return -EINVAL.
 *
 * AUTHOR
 *      Darren Hart <dvhart@linux.intel.com>
 *
 * HISTORY
 *      2009-Nov-9: Initial version by Darren Hart <dvhart@linux.intel.com>
 *
 *****************************************************************************/

#include <errno.h>
#include <getopt.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "futextest.h"
#include "logging.h"


futex_t f1 = FUTEX_INITIALIZER;

futex_t f2 = FUTEX_INITIALIZER;

int child_ret = 0;


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 *blocking_child(void *arg) { child_ret = futex_wait(&f1, f1, NULL, FUTEX_PRIVATE_FLAG); if (child_ret < 0) { child_ret = -errno; error("futex_wait\n", errno); } return (void *)&child_ret; }

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int main(int argc, char *argv[]) { int ret = RET_PASS; pthread_t child; int c; 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); } } printf("%s: Detect mismatched requeue_pi operations\n", basename(argv[0])); if (pthread_create(&child, NULL, blocking_child, NULL)) { error("pthread_create\n", errno); ret = RET_ERROR; goto out; } /* Allow the child to block in the kernel. */ sleep(1); /* * The kernel should detect the waiter did not setup the * q->requeue_pi_key and return -EINVAL. If it does not, * it likely gave the lock to the child, which is now hung * in the kernel. */ ret = futex_cmp_requeue_pi(&f1, f1, &f2, 1, 0, FUTEX_PRIVATE_FLAG); if (ret < 0) { if (errno == EINVAL) { /* * The kernel correctly detected the mismatched * requeue_pi target and aborted. Wake the child with * FUTEX_WAKE. */ ret = futex_wake(&f1, 1, FUTEX_PRIVATE_FLAG); if (ret == 1) { ret = RET_PASS; } else if (ret < 0) { error("futex_wake\n", errno); ret = RET_ERROR; } else { error("futex_wake did not wake the child\n", 0); ret = RET_ERROR; } } else { error("futex_cmp_requeue_pi\n", errno); ret = RET_ERROR; } } else if (ret > 0) { fail("futex_cmp_requeue_pi failed to detect the mismatch\n"); ret = RET_FAIL; } else { error("futex_cmp_requeue_pi found no waiters\n", 0); ret = RET_ERROR; } pthread_join(child, NULL); if (!ret) ret = child_ret; out: /* If the kernel crashes, we shouldn't return at all. */ print_result(ret); return ret; }

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