1 | /* Deallocate a thread structure. |
2 | Copyright (C) 2000-2022 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 | #include <assert.h> |
20 | #include <pthread.h> |
21 | #include <stdlib.h> |
22 | |
23 | #include <pt-internal.h> |
24 | |
25 | #include <atomic.h> |
26 | |
27 | /* List of thread structures corresponding to free thread IDs. */ |
28 | extern struct __pthread *__pthread_free_threads; |
29 | extern pthread_mutex_t __pthread_free_threads_lock; |
30 | |
31 | |
32 | /* Deallocate the content of the thread structure for PTHREAD. */ |
33 | void |
34 | __pthread_dealloc (struct __pthread *pthread) |
35 | { |
36 | if (!atomic_decrement_and_test (&pthread->nr_refs)) |
37 | return; |
38 | |
39 | /* Withdraw this thread from the thread ID lookup table. */ |
40 | __pthread_setid (pthread->thread, NULL); |
41 | |
42 | /* Mark the thread as terminated. We broadcast the condition |
43 | here to prevent pthread_join from waiting for this thread to |
44 | exit where it was never really started. Such a call to |
45 | pthread_join is completely bogus, but unfortunately allowed |
46 | by the standards. */ |
47 | __pthread_mutex_lock (&pthread->state_lock); |
48 | if (pthread->state != PTHREAD_EXITED) |
49 | __pthread_cond_broadcast (&pthread->state_cond); |
50 | __pthread_mutex_unlock (&pthread->state_lock); |
51 | |
52 | /* We do not actually deallocate the thread structure, but add it to |
53 | a list of re-usable thread structures. */ |
54 | __pthread_mutex_lock (&__pthread_free_threads_lock); |
55 | __pthread_enqueue (head: &__pthread_free_threads, thread: pthread); |
56 | __pthread_mutex_unlock (&__pthread_free_threads_lock); |
57 | } |
58 | |
59 | /* Confirm deallocation of the thread structure for PTHREAD. */ |
60 | void |
61 | __pthread_dealloc_finish (struct __pthread *pthread) |
62 | { |
63 | /* Setting PTHREAD->TERMINATED makes this TCB |
64 | available for reuse. After that point, we can no longer assume |
65 | that PTHREAD is valid. |
66 | |
67 | Note that it is safe to not lock this update to PTHREAD->STATE: |
68 | the only way that it can now be accessed is in __pthread_alloc, |
69 | which reads this variable. */ |
70 | pthread->terminated = TRUE; |
71 | } |
72 | |