1 /* Out-of-line notification function for the GSCOPE locking mechanism.
2 Copyright (C) 2007-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
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/>. */
19 #include <nptl/descr.h>
20 #include <futex-internal.h>
23 #include <lowlevellock.h>
26 __thread_gscope_wait (void)
28 lll_lock (GL (dl_stack_cache_lock
), LLL_PRIVATE
);
30 struct pthread
*self
= THREAD_SELF
;
32 /* Iterate over the list with system-allocated threads first. */
34 list_for_each (runp
, &GL (dl_stack_used
))
36 struct pthread
*t
= list_entry (runp
, struct pthread
, list
);
37 if (t
== self
|| t
->header
.gscope_flag
== THREAD_GSCOPE_FLAG_UNUSED
)
40 int *const gscope_flagp
= &t
->header
.gscope_flag
;
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
))
51 futex_wait_simple ((unsigned int *) gscope_flagp
,
52 THREAD_GSCOPE_FLAG_WAIT
, FUTEX_PRIVATE
);
53 while (*gscope_flagp
== THREAD_GSCOPE_FLAG_WAIT
);
56 /* Now the list with threads using user-allocated stacks. */
57 list_for_each (runp
, &GL (dl_stack_user
))
59 struct pthread
*t
= list_entry (runp
, struct pthread
, list
);
60 if (t
== self
|| t
->header
.gscope_flag
== THREAD_GSCOPE_FLAG_UNUSED
)
63 int *const gscope_flagp
= &t
->header
.gscope_flag
;
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
))
74 futex_wait_simple ((unsigned int *) gscope_flagp
,
75 THREAD_GSCOPE_FLAG_WAIT
, FUTEX_PRIVATE
);
76 while (*gscope_flagp
== THREAD_GSCOPE_FLAG_WAIT
);
79 lll_unlock (GL (dl_stack_cache_lock
), LLL_PRIVATE
);