xf.li | bdd93d5 | 2023-05-12 07:10:14 -0700 | [diff] [blame^] | 1 | /* Copyright (C) 2006-2016 Free Software Foundation, Inc. |
| 2 | This file is part of the GNU C Library. |
| 3 | Contributed by Jakub Jelinek <jakub@redhat.com>, 2006. |
| 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 | <http://www.gnu.org/licenses/>. */ |
| 18 | |
| 19 | #include <errno.h> |
| 20 | #include <sysdep.h> |
| 21 | #include <lowlevellock.h> |
| 22 | #include <sys/time.h> |
| 23 | #include <pthreadP.h> |
| 24 | #include <kernel-features.h> |
| 25 | |
| 26 | |
| 27 | int |
| 28 | __lll_robust_lock_wait (int *futex, int private) |
| 29 | { |
| 30 | int oldval = *futex; |
| 31 | int tid = THREAD_GETMEM (THREAD_SELF, tid); |
| 32 | |
| 33 | /* If the futex changed meanwhile try locking again. */ |
| 34 | if (oldval == 0) |
| 35 | goto try; |
| 36 | |
| 37 | do |
| 38 | { |
| 39 | /* If the owner died, return the present value of the futex. */ |
| 40 | if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED)) |
| 41 | return oldval; |
| 42 | |
| 43 | /* Try to put the lock into state 'acquired, possibly with waiters'. */ |
| 44 | int newval = oldval | FUTEX_WAITERS; |
| 45 | if (oldval != newval |
| 46 | && atomic_compare_and_exchange_bool_acq (futex, newval, oldval)) |
| 47 | continue; |
| 48 | |
| 49 | /* If *futex == 2, wait until woken. */ |
| 50 | lll_futex_wait (futex, newval, private); |
| 51 | |
| 52 | try: |
| 53 | ; |
| 54 | } |
| 55 | while ((oldval = atomic_compare_and_exchange_val_acq (futex, |
| 56 | tid | FUTEX_WAITERS, |
| 57 | 0)) != 0); |
| 58 | return 0; |
| 59 | } |
| 60 | |
| 61 | |
| 62 | int |
| 63 | __lll_robust_timedlock_wait (int *futex, const struct timespec *abstime, |
| 64 | int private) |
| 65 | { |
| 66 | /* Reject invalid timeouts. */ |
| 67 | if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) |
| 68 | return EINVAL; |
| 69 | |
| 70 | int tid = THREAD_GETMEM (THREAD_SELF, tid); |
| 71 | int oldval = *futex; |
| 72 | |
| 73 | /* If the futex changed meanwhile, try locking again. */ |
| 74 | if (oldval == 0) |
| 75 | goto try; |
| 76 | |
| 77 | /* Work around the fact that the kernel rejects negative timeout values |
| 78 | despite them being valid. */ |
| 79 | if (__glibc_unlikely (abstime->tv_sec < 0)) |
| 80 | return ETIMEDOUT; |
| 81 | |
| 82 | do |
| 83 | { |
| 84 | #if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \ |
| 85 | || !defined lll_futex_timed_wait_bitset) |
| 86 | struct timeval tv; |
| 87 | struct timespec rt; |
| 88 | |
| 89 | /* Get the current time. */ |
| 90 | (void) __gettimeofday (&tv, NULL); |
| 91 | |
| 92 | /* Compute relative timeout. */ |
| 93 | rt.tv_sec = abstime->tv_sec - tv.tv_sec; |
| 94 | rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000; |
| 95 | if (rt.tv_nsec < 0) |
| 96 | { |
| 97 | rt.tv_nsec += 1000000000; |
| 98 | --rt.tv_sec; |
| 99 | } |
| 100 | |
| 101 | /* Already timed out? */ |
| 102 | if (rt.tv_sec < 0) |
| 103 | return ETIMEDOUT; |
| 104 | #endif |
| 105 | |
| 106 | /* If the owner died, return the present value of the futex. */ |
| 107 | if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED)) |
| 108 | return oldval; |
| 109 | |
| 110 | /* Try to put the lock into state 'acquired, possibly with waiters'. */ |
| 111 | int newval = oldval | FUTEX_WAITERS; |
| 112 | if (oldval != newval |
| 113 | && atomic_compare_and_exchange_bool_acq (futex, newval, oldval)) |
| 114 | continue; |
| 115 | |
| 116 | /* If *futex == 2, wait until woken or timeout. */ |
| 117 | #if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \ |
| 118 | || !defined lll_futex_timed_wait_bitset) |
| 119 | lll_futex_timed_wait (futex, newval, &rt, private); |
| 120 | #else |
| 121 | lll_futex_timed_wait_bitset (futex, newval, abstime, |
| 122 | FUTEX_CLOCK_REALTIME, private); |
| 123 | #endif |
| 124 | |
| 125 | try: |
| 126 | ; |
| 127 | } |
| 128 | while ((oldval = atomic_compare_and_exchange_val_acq (futex, |
| 129 | tid | FUTEX_WAITERS, |
| 130 | 0)) != 0); |
| 131 | |
| 132 | return 0; |
| 133 | } |