1 | /* Bug 22111: Test that threads do not leak their per thread cache. |
2 | Copyright (C) 2015-2022 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | |
19 | /* The point of this test is to start and exit a large number of |
20 | threads, while at the same time looking to see if the used |
21 | memory grows with each round of threads run. If the memory |
22 | grows above some linear bound we declare the test failed and |
23 | that the malloc implementation is leaking memory with each |
24 | thread. This is a good indicator that the thread local cache |
25 | is leaking chunks. */ |
26 | |
27 | #include <stdio.h> |
28 | #include <stdlib.h> |
29 | #include <malloc.h> |
30 | #include <pthread.h> |
31 | #include <assert.h> |
32 | #include <libc-diag.h> |
33 | |
34 | #include <support/check.h> |
35 | #include <support/support.h> |
36 | #include <support/xthread.h> |
37 | |
38 | void * |
39 | worker (void *data) |
40 | { |
41 | void *ret; |
42 | /* Allocate an arbitrary amount of memory that is known to fit into |
43 | the thread local cache (tcache). If we have at least 64 bins |
44 | (default e.g. TCACHE_MAX_BINS) we should be able to allocate 32 |
45 | bytes and force malloc to fill the tcache. We are assuming tcahce |
46 | init happens at the first small alloc, but it might in the future |
47 | be deferred to some other point. Therefore to future proof this |
48 | test we include a full alloc/free/alloc cycle for the thread. We |
49 | need a compiler barrier to avoid the removal of the useless |
50 | alloc/free. We send some memory back to main to have the memory |
51 | freed after the thread dies, as just another check that the chunks |
52 | that were previously in the tcache are still OK to free after |
53 | thread death. */ |
54 | ret = xmalloc (n: 32); |
55 | __asm__ volatile ("" ::: "memory" ); |
56 | free (ptr: ret); |
57 | return (void *) xmalloc (n: 32); |
58 | } |
59 | |
60 | static int |
61 | do_test (void) |
62 | { |
63 | pthread_t *thread; |
64 | struct mallinfo info_before, info_after; |
65 | void *retval; |
66 | |
67 | /* This is an arbitrary choice. We choose a total of THREADS |
68 | threads created and joined. This gives us enough iterations to |
69 | show a leak. */ |
70 | int threads = 100000; |
71 | |
72 | /* Avoid there being 0 malloc'd data at this point by allocating the |
73 | pthread_t required to run the test. */ |
74 | thread = (pthread_t *) xcalloc (n: 1, s: sizeof (pthread_t)); |
75 | |
76 | /* The test below covers the deprecated mallinfo function. */ |
77 | DIAG_PUSH_NEEDS_COMMENT; |
78 | DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wdeprecated-declarations" ); |
79 | |
80 | info_before = mallinfo (); |
81 | |
82 | assert (info_before.uordblks != 0); |
83 | |
84 | printf (format: "INFO: %d (bytes) are in use before starting threads.\n" , |
85 | info_before.uordblks); |
86 | |
87 | for (int loop = 0; loop < threads; loop++) |
88 | { |
89 | *thread = xpthread_create (NULL, thread_func: worker, NULL); |
90 | retval = xpthread_join (thr: *thread); |
91 | free (ptr: retval); |
92 | } |
93 | |
94 | info_after = mallinfo (); |
95 | printf (format: "INFO: %d (bytes) are in use after all threads joined.\n" , |
96 | info_after.uordblks); |
97 | |
98 | /* We need to compare the memory in use before and the memory in use |
99 | after starting and joining THREADS threads. We almost always grow |
100 | memory slightly, but not much. Consider that if even 1-byte leaked |
101 | per thread we'd have THREADS bytes of additional memory, and in |
102 | general the in-use at the start of main is quite low. We will |
103 | always leak a full malloc chunk, and never just 1-byte, therefore |
104 | anything above "+ threads" from the start (constant offset) is a |
105 | leak. Obviously this assumes no thread-related malloc'd internal |
106 | libc data structures persist beyond the thread death, and any that |
107 | did would limit the number of times you could call pthread_create, |
108 | which is a QoI we'd want to detect and fix. */ |
109 | if (info_after.uordblks > (info_before.uordblks + threads)) |
110 | FAIL_EXIT1 ("Memory usage after threads is too high.\n" ); |
111 | |
112 | DIAG_POP_NEEDS_COMMENT; |
113 | |
114 | /* Did not detect excessive memory usage. */ |
115 | free (ptr: thread); |
116 | exit (0); |
117 | } |
118 | |
119 | #define TIMEOUT 50 |
120 | #include <support/test-driver.c> |
121 | |