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 <lowlevelrwlock.h>
22 #include <pthread-errnos.h>
23 #include <kernel-features.h>
25 #include <stap-probe.h>
29 .globl __pthread_rwlock_rdlock
30 .type __pthread_rwlock_rdlock,@function
32 __pthread_rwlock_rdlock:
35 cfi_adjust_cfa_offset(4)
37 cfi_adjust_cfa_offset(4)
44 LIBC_PROBE (rdlock_entry, 1, %ebx)
53 cmpxchgl %edx, MUTEX(%ebx)
57 2: movl WRITER(%ebx), %eax
60 cmpl $0, WRITERS_QUEUED(%ebx)
65 3: addl $1, READERS_QUEUED(%ebx)
68 movl READERS_WAKEUP(%ebx), %edx
79 #ifdef __ASSUME_PRIVATE_FUTEX
80 movzbl PSHARED(%ebx), %ecx
81 xorl $FUTEX_PRIVATE_FLAG|FUTEX_WAIT, %ecx
83 movzbl PSHARED(%ebx), %ecx
87 xorl %gs:PRIVATE_FUTEX, %ecx
89 addl $READERS_WAKEUP, %ebx
93 subl $READERS_WAKEUP, %ebx
100 cmpxchgl %edx, (%ebx)
102 cmpxchgl %edx, MUTEX(%ebx)
106 13: subl $1, READERS_QUEUED(%ebx)
110 addl $1, NR_READERS(%ebx)
123 cfi_adjust_cfa_offset(-4)
126 cfi_adjust_cfa_offset(-4)
130 cfi_adjust_cfa_offset(8)
132 cfi_offset(%ebx, -12)
137 leal MUTEX(%ebx), %edx
139 movzbl PSHARED(%ebx), %ecx
143 14: cmpl %gs:TID, %eax
145 /* Deadlock detected. */
153 leal MUTEX(%ebx), %eax
155 movzbl PSHARED(%ebx), %ecx
156 call __lll_unlock_wake
160 8: subl $1, NR_READERS(%ebx)
165 4: subl $1, READERS_QUEUED(%ebx)
173 leal MUTEX(%ebx), %eax
175 movzbl PSHARED(%ebx), %ecx
176 call __lll_unlock_wake
183 leal MUTEX(%ebx), %edx
185 movzbl PSHARED(%ebx), %ecx
189 .size __pthread_rwlock_rdlock,.-__pthread_rwlock_rdlock
191 strong_alias (__pthread_rwlock_rdlock, pthread_rwlock_rdlock)
192 hidden_def (__pthread_rwlock_rdlock)