| 1 | /* low level locking for pthread library. Generic futex-using version. |
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| 2 | Copyright (C) 2003-2022 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | The GNU C Library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Lesser General Public License for more details. |
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| 14 | |
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| 15 | You should have received a copy of the GNU Lesser General Public |
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| 16 | License along with the GNU C Library; if not, see |
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| 17 | <https://www.gnu.org/licenses/>. */ |
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| 18 | |
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| 19 | #include <sysdep.h> |
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| 20 | #include <futex-internal.h> |
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| 21 | #include <atomic.h> |
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| 22 | #include <stap-probe.h> |
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| 23 | |
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| 24 | void |
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| 25 | __lll_lock_wait_private (int *futex) |
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| 26 | { |
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| 27 | if (atomic_load_relaxed (futex) == 2) |
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| 28 | goto futex; |
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| 29 | |
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| 30 | while (atomic_exchange_acquire (futex, 2) != 0) |
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| 31 | { |
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| 32 | futex: |
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| 33 | LIBC_PROBE (lll_lock_wait_private, 1, futex); |
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| 34 | futex_wait (futex_word: (unsigned int *) futex, expected: 2, LLL_PRIVATE); /* Wait if *futex == 2. */ |
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| 35 | } |
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| 36 | } |
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| 37 | libc_hidden_def (__lll_lock_wait_private) |
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| 38 | |
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| 39 | void |
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| 40 | __lll_lock_wait (int *futex, int private) |
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| 41 | { |
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| 42 | if (atomic_load_relaxed (futex) == 2) |
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| 43 | goto futex; |
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| 44 | |
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| 45 | while (atomic_exchange_acquire (futex, 2) != 0) |
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| 46 | { |
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| 47 | futex: |
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| 48 | LIBC_PROBE (lll_lock_wait, 1, futex); |
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| 49 | futex_wait (futex_word: (unsigned int *) futex, expected: 2, private); /* Wait if *futex == 2. */ |
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| 50 | } |
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| 51 | } |
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| 52 | libc_hidden_def (__lll_lock_wait) |
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| 53 | |
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| 54 | void |
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| 55 | __lll_lock_wake_private (int *futex) |
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| 56 | { |
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| 57 | lll_futex_wake (futex, 1, LLL_PRIVATE); |
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| 58 | } |
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| 59 | libc_hidden_def (__lll_lock_wake_private) |
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| 60 | |
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| 61 | void |
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| 62 | __lll_lock_wake (int *futex, int private) |
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| 63 | { |
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| 64 | lll_futex_wake (futex, 1, private); |
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| 65 | } |
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| 66 | libc_hidden_def (__lll_lock_wake) |
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| 67 | |
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| 68 | #if ENABLE_ELISION_SUPPORT |
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| 69 | int __pthread_force_elision; |
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| 70 | libc_hidden_data_def (__pthread_force_elision) |
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| 71 | #endif |
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| 72 | |
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