1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2015 Yi Zhang <wetpzy@gmail.com>
4 * Li Wang <liwang@redhat.com>
5 *
6 * DESCRIPTION:
7 *
8 * It is a regression test for commit:
9 * http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/
10 * commit/?id=13d60f4
11 *
12 * The implementation of futex doesn't produce unique keys for futexes
13 * in shared huge pages, so threads waiting on different futexes may
14 * end up on the same wait list. This results in incorrect threads being
15 * woken by FUTEX_WAKE.
16 *
17 * Needs to be run as root unless there are already enough huge pages available.
18 * In the fail case, which happens in the CentOS-6.6 kernel (2.6.32-504.8.1),
19 * the tests hangs until it times out after a 30-second wait.
20 *
21 */
22
23 #include <stdio.h>
24 #include <fcntl.h>
25 #include <sys/time.h>
26 #include <string.h>
27
28 #include "futextest.h"
29 #include "futex_utils.h"
30 #include "lapi/mmap.h"
31 #include "tst_safe_stdio.h"
32 #include "tst_safe_pthread.h"
33
34 static futex_t *futex1, *futex2;
35
36 static struct tst_ts to;
37
38 static struct futex_test_variants variants[] = {
39 #if (__NR_futex != __LTP__NR_INVALID_SYSCALL)
40 { .fntype = FUTEX_FN_FUTEX, .tstype = TST_KERN_OLD_TIMESPEC, .desc = "syscall with old kernel spec"},
41 #endif
42
43 #if (__NR_futex_time64 != __LTP__NR_INVALID_SYSCALL)
44 { .fntype = FUTEX_FN_FUTEX64, .tstype = TST_KERN_TIMESPEC, .desc = "syscall time64 with kernel spec"},
45 #endif
46 };
47
setup(void)48 static void setup(void)
49 {
50 struct futex_test_variants *tv = &variants[tst_variant];
51
52 tst_res(TINFO, "Testing variant: %s", tv->desc);
53 futex_supported_by_kernel(tv->fntype);
54
55 to = tst_ts_from_ns(tv->tstype, 30 * NSEC_PER_SEC);
56 }
57
wait_thread1(void * arg LTP_ATTRIBUTE_UNUSED)58 static void *wait_thread1(void *arg LTP_ATTRIBUTE_UNUSED)
59 {
60 struct futex_test_variants *tv = &variants[tst_variant];
61
62 futex_wait(tv->fntype, futex1, *futex1, &to, 0);
63
64 return NULL;
65 }
66
wait_thread2(void * arg LTP_ATTRIBUTE_UNUSED)67 static void *wait_thread2(void *arg LTP_ATTRIBUTE_UNUSED)
68 {
69 struct futex_test_variants *tv = &variants[tst_variant];
70 int res;
71
72 errno = 0;
73 res = futex_wait(tv->fntype, futex2, *futex2, &to, 0);
74 if (!res)
75 tst_res(TPASS, "Hi hydra, thread2 awake!");
76 else
77 tst_res(TFAIL | TERRNO, "Bug: wait_thread2 did not wake after 30 secs.");
78
79 return NULL;
80 }
81
wakeup_thread2(void)82 static void wakeup_thread2(void)
83 {
84 struct futex_test_variants *tv = &variants[tst_variant];
85 void *addr;
86 int hpsz, pgsz;
87 pthread_t th1, th2;
88
89 hpsz = tst_get_hugepage_size();
90 tst_res(TINFO, "Hugepagesize %i", hpsz);
91
92 /*allocate some shared memory*/
93 addr = mmap(NULL, hpsz, PROT_WRITE | PROT_READ,
94 MAP_SHARED | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);
95
96 if (addr == MAP_FAILED) {
97 if (errno == ENOMEM)
98 tst_brk(TCONF, "Cannot allocate hugepage, memory too fragmented?");
99
100 tst_brk(TBROK | TERRNO, "Cannot allocate hugepage");
101 }
102
103 pgsz = getpagesize();
104
105 /*apply the first subpage to futex1*/
106 futex1 = addr;
107 *futex1 = 0;
108 /*apply the second subpage to futex2*/
109 futex2 = (futex_t *)((char *)addr + pgsz);
110 *futex2 = 0;
111
112 /*thread1 block on futex1 first,then thread2 block on futex2*/
113 SAFE_PTHREAD_CREATE(&th1, NULL, wait_thread1, NULL);
114 SAFE_PTHREAD_CREATE(&th2, NULL, wait_thread2, NULL);
115
116 while (wait_for_threads(2))
117 usleep(1000);
118
119 futex_wake(tv->fntype, futex2, 1, 0);
120 SAFE_PTHREAD_JOIN(th2, NULL);
121 futex_wake(tv->fntype, futex1, 1, 0);
122 SAFE_PTHREAD_JOIN(th1, NULL);
123
124 SAFE_MUNMAP(addr, hpsz);
125 }
126
127 static struct tst_test test = {
128 .setup = setup,
129 .test_all = wakeup_thread2,
130 .test_variants = ARRAY_SIZE(variants),
131 .needs_root = 1,
132 .needs_tmpdir = 1,
133 .hugepages = {1, TST_NEEDS},
134 };
135