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1daccf40 | 1 | /* Out-of-line notification function for the GSCOPE locking mechanism. |
2b778ceb | 2 | Copyright (C) 2007-2021 Free Software Foundation, Inc. |
1daccf40 FW |
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 | #include <nptl/descr.h> | |
20 | #include <futex-internal.h> | |
21 | #include <ldsodefs.h> | |
22 | #include <list.h> | |
23 | #include <lowlevellock.h> | |
24 | ||
25 | void | |
26 | __thread_gscope_wait (void) | |
27 | { | |
28 | lll_lock (GL (dl_stack_cache_lock), LLL_PRIVATE); | |
29 | ||
30 | struct pthread *self = THREAD_SELF; | |
31 | ||
32 | /* Iterate over the list with system-allocated threads first. */ | |
33 | list_t *runp; | |
34 | list_for_each (runp, &GL (dl_stack_used)) | |
35 | { | |
36 | struct pthread *t = list_entry (runp, struct pthread, list); | |
37 | if (t == self || t->header.gscope_flag == THREAD_GSCOPE_FLAG_UNUSED) | |
38 | continue; | |
39 | ||
40 | int *const gscope_flagp = &t->header.gscope_flag; | |
41 | ||
42 | /* We have to wait until this thread is done with the global | |
43 | scope. First tell the thread that we are waiting and | |
44 | possibly have to be woken. */ | |
45 | if (atomic_compare_and_exchange_bool_acq (gscope_flagp, | |
46 | THREAD_GSCOPE_FLAG_WAIT, | |
47 | THREAD_GSCOPE_FLAG_USED)) | |
48 | continue; | |
49 | ||
50 | do | |
51 | futex_wait_simple ((unsigned int *) gscope_flagp, | |
52 | THREAD_GSCOPE_FLAG_WAIT, FUTEX_PRIVATE); | |
53 | while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT); | |
54 | } | |
55 | ||
56 | /* Now the list with threads using user-allocated stacks. */ | |
57 | list_for_each (runp, &GL (dl_stack_user)) | |
58 | { | |
59 | struct pthread *t = list_entry (runp, struct pthread, list); | |
60 | if (t == self || t->header.gscope_flag == THREAD_GSCOPE_FLAG_UNUSED) | |
61 | continue; | |
62 | ||
63 | int *const gscope_flagp = &t->header.gscope_flag; | |
64 | ||
65 | /* We have to wait until this thread is done with the global | |
66 | scope. First tell the thread that we are waiting and | |
67 | possibly have to be woken. */ | |
68 | if (atomic_compare_and_exchange_bool_acq (gscope_flagp, | |
69 | THREAD_GSCOPE_FLAG_WAIT, | |
70 | THREAD_GSCOPE_FLAG_USED)) | |
71 | continue; | |
72 | ||
73 | do | |
74 | futex_wait_simple ((unsigned int *) gscope_flagp, | |
75 | THREAD_GSCOPE_FLAG_WAIT, FUTEX_PRIVATE); | |
76 | while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT); | |
77 | } | |
78 | ||
79 | lll_unlock (GL (dl_stack_cache_lock), LLL_PRIVATE); | |
80 | } |