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65810f0ef0
lll_robust_unlock on i386 and x86_64 first sets the futex word to FUTEX_WAITERS|0 before calling __lll_unlock_wake, which will set the futex word to 0. If the thread is killed between these steps, then the futex word will be FUTEX_WAITERS|0, and the kernel (at least current upstream) will not set it to FUTEX_OWNER_DIED|FUTEX_WAITERS because 0 is not equal to the TID of the crashed thread. The lll_robust_lock assembly code on i386 and x86_64 is not prepared to deal with this case because the fastpath tries to only CAS 0 to TID and not FUTEX_WAITERS|0 to TID; the slowpath simply waits until it can CAS 0 to TID or the futex_word has the FUTEX_OWNER_DIED bit set. This issue is fixed by removing the custom x86 assembly code and using the generic C code instead. However, instead of adding more duplicate code to the custom x86 lowlevellock.h, the code of the lll_robust* functions is inlined into the single call sites that exist for each of these functions in the pthread_mutex_* functions. The robust mutex paths in the latter have been slightly reorganized to make them simpler. This patch is meant to be easy to backport, so C11-style atomics are not used. [BZ #20985] * nptl/Makefile: Adapt. * nptl/pthread_mutex_cond_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove. (LLL_ROBUST_MUTEX_LOCK_MODIFIER): New. * nptl/pthread_mutex_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove. (LLL_ROBUST_MUTEX_LOCK_MODIFIER): New. (__pthread_mutex_lock_full): Inline lll_robust* functions and adapt. * nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Inline lll_robust* functions and adapt. * nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise. * sysdeps/nptl/lowlevellock.h (__lll_robust_lock_wait, __lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait, __lll_robust_timedlock, __lll_robust_unlock): Remove. * sysdeps/unix/sysv/linux/i386/lowlevellock.h (lll_robust_lock, lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove. * sysdeps/unix/sysv/linux/x86_64/lowlevellock.h (lll_robust_lock, lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove. * sysdeps/unix/sysv/linux/sparc/lowlevellock.h (__lll_robust_lock_wait, __lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait, __lll_robust_timedlock, __lll_robust_unlock): Remove. * nptl/lowlevelrobustlock.c: Remove file. * nptl/lowlevelrobustlock.sym: Likewise. * sysdeps/unix/sysv/linux/i386/lowlevelrobustlock.S: Likewise. * sysdeps/unix/sysv/linux/x86_64/lowlevelrobustlock.S: Likewise.
268 lines
8.9 KiB
C
268 lines
8.9 KiB
C
/* Copyright (C) 2002-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _LOWLEVELLOCK_H
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#define _LOWLEVELLOCK_H 1
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#include <stap-probe.h>
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#ifndef __ASSEMBLER__
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# include <time.h>
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# include <sys/param.h>
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# include <bits/pthreadtypes.h>
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# include <kernel-features.h>
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# include <tcb-offsets.h>
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# ifndef LOCK_INSTR
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# ifdef UP
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# define LOCK_INSTR /* nothing */
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# else
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# define LOCK_INSTR "lock;"
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# endif
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# endif
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#else
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# ifndef LOCK
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# ifdef UP
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# define LOCK
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# else
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# define LOCK lock
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# endif
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# endif
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#endif
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#include <lowlevellock-futex.h>
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/* XXX Remove when no assembler code uses futexes anymore. */
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#define SYS_futex __NR_futex
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#ifndef __ASSEMBLER__
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/* Initializer for compatibility lock. */
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#define LLL_LOCK_INITIALIZER (0)
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#define LLL_LOCK_INITIALIZER_LOCKED (1)
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#define LLL_LOCK_INITIALIZER_WAITERS (2)
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/* NB: in the lll_trylock macro we simply return the value in %eax
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after the cmpxchg instruction. In case the operation succeded this
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value is zero. In case the operation failed, the cmpxchg instruction
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has loaded the current value of the memory work which is guaranteed
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to be nonzero. */
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#if !IS_IN (libc) || defined UP
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# define __lll_trylock_asm LOCK_INSTR "cmpxchgl %2, %1"
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#else
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# define __lll_trylock_asm "cmpl $0, %%gs:%P5\n\t" \
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"je 0f\n\t" \
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"lock\n" \
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"0:\tcmpxchgl %2, %1"
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#endif
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#define lll_trylock(futex) \
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({ int ret; \
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__asm __volatile (__lll_trylock_asm \
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: "=a" (ret), "=m" (futex) \
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: "r" (LLL_LOCK_INITIALIZER_LOCKED), "m" (futex), \
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"0" (LLL_LOCK_INITIALIZER), \
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"i" (MULTIPLE_THREADS_OFFSET) \
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: "memory"); \
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ret; })
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#define lll_cond_trylock(futex) \
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({ int ret; \
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__asm __volatile (LOCK_INSTR "cmpxchgl %2, %1" \
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: "=a" (ret), "=m" (futex) \
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: "r" (LLL_LOCK_INITIALIZER_WAITERS), \
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"m" (futex), "0" (LLL_LOCK_INITIALIZER) \
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: "memory"); \
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ret; })
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#if !IS_IN (libc) || defined UP
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# define __lll_lock_asm_start LOCK_INSTR "cmpxchgl %1, %2\n\t"
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#else
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# define __lll_lock_asm_start "cmpl $0, %%gs:%P6\n\t" \
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"je 0f\n\t" \
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"lock\n" \
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"0:\tcmpxchgl %1, %2\n\t"
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#endif
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#define lll_lock(futex, private) \
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(void) \
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({ int ignore1, ignore2; \
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if (__builtin_constant_p (private) && (private) == LLL_PRIVATE) \
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__asm __volatile (__lll_lock_asm_start \
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"jz 18f\n\t" \
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"1:\tleal %2, %%ecx\n" \
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"2:\tcall __lll_lock_wait_private\n" \
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"18:" \
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: "=a" (ignore1), "=c" (ignore2), "=m" (futex) \
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: "0" (0), "1" (1), "m" (futex), \
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"i" (MULTIPLE_THREADS_OFFSET) \
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: "memory"); \
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else \
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{ \
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int ignore3; \
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__asm __volatile (__lll_lock_asm_start \
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"jz 18f\n\t" \
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"1:\tleal %2, %%edx\n" \
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"0:\tmovl %8, %%ecx\n" \
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"2:\tcall __lll_lock_wait\n" \
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"18:" \
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: "=a" (ignore1), "=c" (ignore2), \
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"=m" (futex), "=&d" (ignore3) \
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: "1" (1), "m" (futex), \
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"i" (MULTIPLE_THREADS_OFFSET), "0" (0), \
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"g" ((int) (private)) \
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: "memory"); \
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} \
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})
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/* Special version of lll_lock which causes the unlock function to
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always wakeup waiters. */
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#define lll_cond_lock(futex, private) \
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(void) \
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({ int ignore1, ignore2, ignore3; \
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__asm __volatile (LOCK_INSTR "cmpxchgl %1, %2\n\t" \
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"jz 18f\n\t" \
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"1:\tleal %2, %%edx\n" \
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"0:\tmovl %7, %%ecx\n" \
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"2:\tcall __lll_lock_wait\n" \
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"18:" \
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: "=a" (ignore1), "=c" (ignore2), "=m" (futex), \
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"=&d" (ignore3) \
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: "0" (0), "1" (2), "m" (futex), "g" ((int) (private))\
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: "memory"); \
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})
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#define lll_timedlock(futex, timeout, private) \
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({ int result, ignore1, ignore2, ignore3; \
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__asm __volatile (LOCK_INSTR "cmpxchgl %1, %3\n\t" \
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"jz 18f\n\t" \
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"1:\tleal %3, %%ecx\n" \
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"0:\tmovl %8, %%edx\n" \
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"2:\tcall __lll_timedlock_wait\n" \
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"18:" \
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: "=a" (result), "=c" (ignore1), "=&d" (ignore2), \
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"=m" (futex), "=S" (ignore3) \
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: "0" (0), "1" (1), "m" (futex), "m" (timeout), \
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"4" ((int) (private)) \
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: "memory"); \
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result; })
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extern int __lll_timedlock_elision (int *futex, short *adapt_count,
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const struct timespec *timeout,
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int private) attribute_hidden;
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#define lll_timedlock_elision(futex, adapt_count, timeout, private) \
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__lll_timedlock_elision(&(futex), &(adapt_count), timeout, private)
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#if !IS_IN (libc) || defined UP
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# define __lll_unlock_asm LOCK_INSTR "subl $1, %0\n\t"
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#else
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# define __lll_unlock_asm "cmpl $0, %%gs:%P3\n\t" \
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"je 0f\n\t" \
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"lock\n" \
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"0:\tsubl $1,%0\n\t"
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#endif
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#define lll_unlock(futex, private) \
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(void) \
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({ int ignore; \
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if (__builtin_constant_p (private) && (private) == LLL_PRIVATE) \
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__asm __volatile (__lll_unlock_asm \
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"je 18f\n\t" \
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"1:\tleal %0, %%eax\n" \
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"2:\tcall __lll_unlock_wake_private\n" \
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"18:" \
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: "=m" (futex), "=&a" (ignore) \
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: "m" (futex), "i" (MULTIPLE_THREADS_OFFSET) \
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: "memory"); \
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else \
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{ \
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int ignore2; \
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__asm __volatile (__lll_unlock_asm \
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"je 18f\n\t" \
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"1:\tleal %0, %%eax\n" \
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"0:\tmovl %5, %%ecx\n" \
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"2:\tcall __lll_unlock_wake\n" \
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"18:" \
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: "=m" (futex), "=&a" (ignore), "=&c" (ignore2) \
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: "i" (MULTIPLE_THREADS_OFFSET), "m" (futex), \
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"g" ((int) (private)) \
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: "memory"); \
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} \
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})
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#define lll_islocked(futex) \
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(futex != LLL_LOCK_INITIALIZER)
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/* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
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wake-up when the clone terminates. The memory location contains the
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thread ID while the clone is running and is reset to zero by the kernel
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afterwards. The kernel up to version 3.16.3 does not use the private futex
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operations for futex wake-up when the clone terminates. */
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#define lll_wait_tid(tid) \
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do { \
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__typeof (tid) __tid; \
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while ((__tid = (tid)) != 0) \
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lll_futex_wait (&(tid), __tid, LLL_SHARED);\
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} while (0)
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extern int __lll_timedwait_tid (int *tid, const struct timespec *abstime)
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__attribute__ ((regparm (2))) attribute_hidden;
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/* As lll_wait_tid, but with a timeout. If the timeout occurs then return
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ETIMEDOUT. If ABSTIME is invalid, return EINVAL.
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XXX Note that this differs from the generic version in that we do the
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error checking here and not in __lll_timedwait_tid. */
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#define lll_timedwait_tid(tid, abstime) \
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({ \
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int __result = 0; \
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if ((tid) != 0) \
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{ \
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if ((abstime)->tv_nsec < 0 || (abstime)->tv_nsec >= 1000000000) \
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__result = EINVAL; \
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else \
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__result = __lll_timedwait_tid (&(tid), (abstime)); \
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} \
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__result; })
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extern int __lll_lock_elision (int *futex, short *adapt_count, int private)
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attribute_hidden;
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extern int __lll_unlock_elision(int *lock, int private)
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attribute_hidden;
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extern int __lll_trylock_elision(int *lock, short *adapt_count)
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attribute_hidden;
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#define lll_lock_elision(futex, adapt_count, private) \
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__lll_lock_elision (&(futex), &(adapt_count), private)
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#define lll_unlock_elision(futex, adapt_count, private) \
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__lll_unlock_elision (&(futex), private)
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#define lll_trylock_elision(futex, adapt_count) \
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__lll_trylock_elision(&(futex), &(adapt_count))
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#endif /* !__ASSEMBLER__ */
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#endif /* lowlevellock.h */
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