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/* Copyright (C) 2002-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <lowlevellock.h>
#include <lowlevelrwlock.h>
#include <pthread-errnos.h>
#include <kernel-features.h>
#include <stap-probe.h>
.text
.globl __pthread_rwlock_rdlock
.type __pthread_rwlock_rdlock,@function
.align 16
__pthread_rwlock_rdlock:
cfi_startproc
pushl %esi
cfi_adjust_cfa_offset(4)
pushl %ebx
cfi_adjust_cfa_offset(4)
cfi_offset(%esi, -8)
cfi_offset(%ebx, -12)
xorl %esi, %esi
movl 12(%esp), %ebx
LIBC_PROBE (rdlock_entry, 1, %ebx)
/* Get the lock. */
movl $1, %edx
xorl %eax, %eax
LOCK
#if MUTEX == 0
cmpxchgl %edx, (%ebx)
#else
cmpxchgl %edx, MUTEX(%ebx)
#endif
jnz 1f
2: movl WRITER(%ebx), %eax
testl %eax, %eax
jne 14f
cmpl $0, WRITERS_QUEUED(%ebx)
je 5f
cmpb $0, FLAGS(%ebx)
je 5f
3: addl $1, READERS_QUEUED(%ebx)
je 4f
movl READERS_WAKEUP(%ebx), %edx
LOCK
#if MUTEX == 0
subl $1, (%ebx)
#else
subl $1, MUTEX(%ebx)
#endif
jne 10f
11:
#ifdef __ASSUME_PRIVATE_FUTEX
movzbl PSHARED(%ebx), %ecx
xorl $FUTEX_PRIVATE_FLAG|FUTEX_WAIT, %ecx
#else
movzbl PSHARED(%ebx), %ecx
# if FUTEX_WAIT != 0
orl $FUTEX_WAIT, %ecx
# endif
xorl %gs:PRIVATE_FUTEX, %ecx
#endif
addl $READERS_WAKEUP, %ebx
movl $SYS_futex, %eax
ENTER_KERNEL
subl $READERS_WAKEUP, %ebx
/* Reget the lock. */
movl $1, %edx
xorl %eax, %eax
LOCK
#if MUTEX == 0
cmpxchgl %edx, (%ebx)
#else
cmpxchgl %edx, MUTEX(%ebx)
#endif
jnz 12f
13: subl $1, READERS_QUEUED(%ebx)
jmp 2b
5: xorl %edx, %edx
addl $1, NR_READERS(%ebx)
je 8f
9: LOCK
#if MUTEX == 0
subl $1, (%ebx)
#else
subl $1, MUTEX(%ebx)
#endif
jne 6f
7:
movl %edx, %eax
popl %ebx
cfi_adjust_cfa_offset(-4)
cfi_restore(%ebx)
popl %esi
cfi_adjust_cfa_offset(-4)
cfi_restore(%esi)
ret
cfi_adjust_cfa_offset(8)
cfi_offset(%esi, -8)
cfi_offset(%ebx, -12)
1:
#if MUTEX == 0
movl %ebx, %edx
#else
leal MUTEX(%ebx), %edx
#endif
movzbl PSHARED(%ebx), %ecx
call __lll_lock_wait
jmp 2b
14: cmpl %gs:TID, %eax
jne 3b
/* Deadlock detected. */
movl $EDEADLK, %edx
jmp 9b
6:
#if MUTEX == 0
movl %ebx, %eax
#else
leal MUTEX(%ebx), %eax
#endif
movzbl PSHARED(%ebx), %ecx
call __lll_unlock_wake
jmp 7b
/* Overflow. */
8: subl $1, NR_READERS(%ebx)
movl $EAGAIN, %edx
jmp 9b
/* Overflow. */
4: subl $1, READERS_QUEUED(%ebx)
movl $EAGAIN, %edx
jmp 9b
10:
#if MUTEX == 0
movl %ebx, %eax
#else
leal MUTEX(%ebx), %eax
#endif
movzbl PSHARED(%ebx), %ecx
call __lll_unlock_wake
jmp 11b
12:
#if MUTEX == 0
movl %ebx, %edx
#else
leal MUTEX(%ebx), %edx
#endif
movzbl PSHARED(%ebx), %ecx
call __lll_lock_wait
jmp 13b
cfi_endproc
.size __pthread_rwlock_rdlock,.-__pthread_rwlock_rdlock
strong_alias (__pthread_rwlock_rdlock, pthread_rwlock_rdlock)
hidden_def (__pthread_rwlock_rdlock)
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