1 /* Copyright (C) 2002-2014 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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.
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.
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/>. */
20 #include <lowlevellock.h>
21 #include <lowlevelbarrier.h>
25 .globl pthread_barrier_wait
26 .type pthread_barrier_wait,@function
31 cfi_adjust_cfa_offset(4)
40 cmpxchgl %edx, MUTEX(%ebx)
43 /* One less waiter. If this was the last one needed wake
45 2: subl $1, LEFT(%ebx)
48 /* There are more threads to come. */
50 cfi_adjust_cfa_offset(4)
56 movl CURR_EVENT(%ebx), %edx
59 /* Release the mutex. */
64 /* Wait for the remaining threads. The call will return immediately
65 if the CURR_EVENT memory has meanwhile been changed. */
68 movl PRIVATE(%ebx), %ecx
70 movl $FUTEX_WAIT, %ecx
71 orl PRIVATE(%ebx), %ecx
74 8: movl $SYS_futex, %eax
77 /* Don't return on spurious wakeups. The syscall does not change
78 any register except %eax so there is no need to reload any of
83 cmpl %edx, CURR_EVENT(%ebx)
87 /* Increment LEFT. If this brings the count back to the
88 initial count unlock the object. */
90 movl INIT_COUNT(%ebx), %ecx
92 xaddl %edx, LEFT(%ebx)
97 /* Release the mutex. We cannot release the lock before
98 waking the waiting threads since otherwise a new thread might
99 arrive and gets waken up, too. */
104 /* Note: %esi is still zero. */
105 10: movl %esi, %eax /* != PTHREAD_BARRIER_SERIAL_THREAD */
108 cfi_adjust_cfa_offset(-4)
111 cfi_adjust_cfa_offset(-4)
115 cfi_adjust_cfa_offset(4)
118 /* The necessary number of threads arrived. */
123 addl $1, CURR_EVENT(%ebx)
126 /* Wake up all waiters. The count is a signed number in the kernel
127 so 0x7fffffff is the highest value. */
128 movl $0x7fffffff, %edx
129 movl $FUTEX_WAKE, %ecx
130 orl PRIVATE(%ebx), %ecx
131 movl $SYS_futex, %eax
134 /* Increment LEFT. If this brings the count back to the
135 initial count unlock the object. */
137 movl INIT_COUNT(%ebx), %ecx
139 xaddl %edx, LEFT(%ebx)
144 /* Release the mutex. We cannot release the lock before
145 waking the waiting threads since otherwise a new thread might
146 arrive and gets waken up, too. */
151 5: orl $-1, %eax /* == PTHREAD_BARRIER_SERIAL_THREAD */
154 cfi_adjust_cfa_offset(-4)
158 cfi_adjust_cfa_offset(4)
160 1: movl PRIVATE(%ebx), %ecx
161 leal MUTEX(%ebx), %edx
162 xorl $LLL_SHARED, %ecx
166 4: movl PRIVATE(%ebx), %ecx
167 leal MUTEX(%ebx), %eax
168 xorl $LLL_SHARED, %ecx
169 call __lll_unlock_wake
172 cfi_adjust_cfa_offset(4)
173 cfi_offset(%esi, -12)
174 6: movl PRIVATE(%ebx), %ecx
175 leal MUTEX(%ebx), %eax
176 xorl $LLL_SHARED, %ecx
177 call __lll_unlock_wake
180 9: movl PRIVATE(%ebx), %ecx
181 leal MUTEX(%ebx), %eax
182 xorl $LLL_SHARED, %ecx
183 call __lll_unlock_wake
186 .size pthread_barrier_wait,.-pthread_barrier_wait