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6d7e8eda | 1 | /* Copyright (C) 2003-2023 Free Software Foundation, Inc. |
a88c9263 | 2 | This file is part of the GNU C Library. |
a88c9263 UD |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or | |
5 | modify it under the terms of the GNU Lesser General Public | |
6 | License as published by the Free Software Foundation; either | |
7 | version 2.1 of the License, or (at your option) any later version. | |
8 | ||
9 | The GNU C Library is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | Lesser General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 | 15 | License along with the GNU C Library; if not, see |
5a82c748 | 16 | <https://www.gnu.org/licenses/>. */ |
a88c9263 UD |
17 | |
18 | #include <endian.h> | |
19 | #include <errno.h> | |
20 | #include <sysdep.h> | |
ed19993b | 21 | #include <futex-internal.h> |
a88c9263 UD |
22 | #include <pthread.h> |
23 | #include <pthreadP.h> | |
5acf7263 | 24 | #include <stap-probe.h> |
ed19993b | 25 | #include <atomic.h> |
a88c9263 UD |
26 | |
27 | #include <shlib-compat.h> | |
28 | ||
ed19993b | 29 | #include "pthread_cond_common.c" |
a88c9263 | 30 | |
ed19993b TR |
31 | |
32 | /* We do the following steps from __pthread_cond_signal in one critical | |
33 | section: (1) signal all waiters in G1, (2) close G1 so that it can become | |
34 | the new G2 and make G2 the new G1, and (3) signal all waiters in the new | |
35 | G1. We don't need to do all these steps if there are no waiters in G1 | |
36 | and/or G2. See __pthread_cond_signal for further details. */ | |
a88c9263 | 37 | int |
08129b15 | 38 | ___pthread_cond_broadcast (pthread_cond_t *cond) |
a88c9263 | 39 | { |
5acf7263 RM |
40 | LIBC_PROBE (cond_broadcast, 1, cond); |
41 | ||
ed19993b TR |
42 | unsigned int wrefs = atomic_load_relaxed (&cond->__data.__wrefs); |
43 | if (wrefs >> 3 == 0) | |
44 | return 0; | |
45 | int private = __condvar_get_private (wrefs); | |
46 | ||
47 | __condvar_acquire_lock (cond, private); | |
a88c9263 | 48 | |
ed19993b TR |
49 | unsigned long long int wseq = __condvar_load_wseq_relaxed (cond); |
50 | unsigned int g2 = wseq & 1; | |
51 | unsigned int g1 = g2 ^ 1; | |
52 | wseq >>= 1; | |
53 | bool do_futex_wake = false; | |
54 | ||
55 | /* Step (1): signal all waiters remaining in G1. */ | |
56 | if (cond->__data.__g_size[g1] != 0) | |
a88c9263 | 57 | { |
ed19993b TR |
58 | /* Add as many signals as the remaining size of the group. */ |
59 | atomic_fetch_add_relaxed (cond->__data.__g_signals + g1, | |
60 | cond->__data.__g_size[g1] << 1); | |
61 | cond->__data.__g_size[g1] = 0; | |
62 | ||
63 | /* We need to wake G1 waiters before we quiesce G1 below. */ | |
64 | /* TODO Only set it if there are indeed futex waiters. We could | |
65 | also try to move this out of the critical section in cases when | |
66 | G2 is empty (and we don't need to quiesce). */ | |
67 | futex_wake (cond->__data.__g_signals + g1, INT_MAX, private); | |
a88c9263 UD |
68 | } |
69 | ||
ed19993b TR |
70 | /* G1 is complete. Step (2) is next unless there are no waiters in G2, in |
71 | which case we can stop. */ | |
72 | if (__condvar_quiesce_and_switch_g1 (cond, wseq, &g1, private)) | |
73 | { | |
74 | /* Step (3): Send signals to all waiters in the old G2 / new G1. */ | |
75 | atomic_fetch_add_relaxed (cond->__data.__g_signals + g1, | |
76 | cond->__data.__g_size[g1] << 1); | |
77 | cond->__data.__g_size[g1] = 0; | |
78 | /* TODO Only set it if there are indeed futex waiters. */ | |
79 | do_futex_wake = true; | |
80 | } | |
81 | ||
82 | __condvar_release_lock (cond, private); | |
83 | ||
84 | if (do_futex_wake) | |
85 | futex_wake (cond->__data.__g_signals + g1, INT_MAX, private); | |
a88c9263 UD |
86 | |
87 | return 0; | |
88 | } | |
08129b15 FW |
89 | versioned_symbol (libc, ___pthread_cond_broadcast, |
90 | pthread_cond_broadcast, GLIBC_2_3_2); | |
91 | libc_hidden_ver (___pthread_cond_broadcast, __pthread_cond_broadcast) | |
0431f171 FW |
92 | #ifndef SHARED |
93 | strong_alias (___pthread_cond_broadcast, __pthread_cond_broadcast) | |
94 | #endif |