1 | /* sem_wait -- wait on a semaphore. Generic futex-using version. |
2 | Copyright (C) 2003-2016 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003. |
5 | |
6 | The GNU C Library is free software; you can redistribute it and/or |
7 | modify it under the terms of the GNU Lesser General Public |
8 | License as published by the Free Software Foundation; either |
9 | version 2.1 of the License, or (at your option) any later version. |
10 | |
11 | The GNU C Library is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
14 | Lesser General Public License for more details. |
15 | |
16 | You should have received a copy of the GNU Lesser General Public |
17 | License along with the GNU C Library; if not, see |
18 | <http://www.gnu.org/licenses/>. */ |
19 | |
20 | #include <lowlevellock.h> /* lll_futex* used by the old code. */ |
21 | #include "sem_waitcommon.c" |
22 | |
23 | int |
24 | __new_sem_wait (sem_t *sem) |
25 | { |
26 | if (__new_sem_wait_fast ((struct new_sem *) sem, 0) == 0) |
27 | return 0; |
28 | else |
29 | return __new_sem_wait_slow((struct new_sem *) sem, NULL); |
30 | } |
31 | versioned_symbol (libpthread, __new_sem_wait, sem_wait, GLIBC_2_1); |
32 | |
33 | #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1) |
34 | int |
35 | attribute_compat_text_section |
36 | __old_sem_wait (sem_t *sem) |
37 | { |
38 | int *futex = (int *) sem; |
39 | int err; |
40 | |
41 | do |
42 | { |
43 | if (atomic_decrement_if_positive (futex) > 0) |
44 | return 0; |
45 | |
46 | /* Enable asynchronous cancellation. Required by the standard. */ |
47 | int oldtype = __pthread_enable_asynccancel (); |
48 | |
49 | /* Always assume the semaphore is shared. */ |
50 | err = lll_futex_wait (futex, 0, LLL_SHARED); |
51 | |
52 | /* Disable asynchronous cancellation. */ |
53 | __pthread_disable_asynccancel (oldtype); |
54 | } |
55 | while (err == 0 || err == -EWOULDBLOCK); |
56 | |
57 | __set_errno (-err); |
58 | return -1; |
59 | } |
60 | |
61 | compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0); |
62 | #endif |
63 | |
64 | int |
65 | __new_sem_trywait (sem_t *sem) |
66 | { |
67 | /* We must not fail spuriously, so require a definitive result even if this |
68 | may lead to a long execution time. */ |
69 | if (__new_sem_wait_fast ((struct new_sem *) sem, 1) == 0) |
70 | return 0; |
71 | __set_errno (EAGAIN); |
72 | return -1; |
73 | } |
74 | versioned_symbol (libpthread, __new_sem_trywait, sem_trywait, GLIBC_2_1); |
75 | #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1) |
76 | int |
77 | __old_sem_trywait (sem_t *sem) |
78 | { |
79 | int *futex = (int *) sem; |
80 | int val; |
81 | |
82 | if (*futex > 0) |
83 | { |
84 | val = atomic_decrement_if_positive (futex); |
85 | if (val > 0) |
86 | return 0; |
87 | } |
88 | |
89 | __set_errno (EAGAIN); |
90 | return -1; |
91 | } |
92 | compat_symbol (libpthread, __old_sem_trywait, sem_trywait, GLIBC_2_0); |
93 | #endif |
94 | |