tequilaOS/platform_hardware_tequila_compat
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

compat: libc: Trim down pthread_cond_timedwait hack

Browse source 
Change-Id: Ie53c8358dd0fd3d05c56353d3b388467d082241c
This commit is contained in:
Nich 2018-09-12 12:32:16 +08:00 committed by Jan Altensen (Stricted)
parent 5c6ed67f4e
commit ae85aa2b64
6 changed files with 19 additions and 423 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
libc/Android.mk
View file

@ -17,15 +17,10 @@ LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SRC_FILES := \
bionic/bionic_time_conversions.cpp \
bionic/pthread_cond.cpp
bionic/pthread_cond_timedwait.cpp
LOCAL_SHARED_LIBRARIES := libc
LOCAL_MODULE := libshim_pthreadts
LOCAL_VENDOR_MODULE := true
# TODO: remove as soon as we find out why Clang breaks camera preflash
LOCAL_CLANG := false
LOCAL_CXX_STL := none
LOCAL_SANITIZE := never
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE_CLASS := SHARED_LIBRARIES
include $(BUILD_SHARED_LIBRARY)

215
libc/bionic/pthread_cond.cpp
View file

@ -1,215 +0,0 @@
#include <pthread.h>
#include <errno.h>
#include <limits.h>
#include <stdatomic.h>
#include <sys/mman.h>
#include <time.h>
#include <unistd.h>
#include "private/bionic_futex.h"
#include "private/bionic_time_conversions.h"
// XXX *technically* there is a race condition that could allow
// XXX a signal to be missed. If thread A is preempted in _wait()
// XXX after unlocking the mutex and before waiting, and if other
// XXX threads call signal or broadcast UINT_MAX/2 times (exactly),
// XXX before thread A is scheduled again and calls futex_wait(),
// XXX then the signal will be lost.
// We use one bit in pthread_condattr_t (long) values as the 'shared' flag
// and one bit for the clock type (CLOCK_REALTIME is 0 and
// CLOCK_MONOTONIC is 1). The rest of the bits are a counter.
//
// The 'value' field in pthread_cond_t has the same layout.
#define COND_SHARED_MASK 0x0001
#define COND_CLOCK_MASK 0x0002
#define COND_COUNTER_STEP 0x0004
#define COND_FLAGS_MASK (COND_SHARED_MASK | COND_CLOCK_MASK)
#define COND_COUNTER_MASK (~COND_FLAGS_MASK)
#define COND_IS_SHARED(c) (((c) & COND_SHARED_MASK) != 0)
#define COND_GET_CLOCK(c) (((c) & COND_CLOCK_MASK) >> 1)
#define COND_SET_CLOCK(attr, c) ((attr) | (c << 1))
int pthread_condattr_init(pthread_condattr_t* attr) {
*attr = 0;
*attr |= PTHREAD_PROCESS_PRIVATE;
*attr |= (CLOCK_REALTIME << 1);
return 0;
}
int pthread_condattr_getpshared(const pthread_condattr_t* attr, int* pshared) {
*pshared = static_cast<int>(COND_IS_SHARED(*attr));
return 0;
}
int pthread_condattr_setpshared(pthread_condattr_t* attr, int pshared) {
if (pshared != PTHREAD_PROCESS_SHARED && pshared != PTHREAD_PROCESS_PRIVATE) {
return EINVAL;
}
*attr |= pshared;
return 0;
}
int pthread_condattr_getclock(const pthread_condattr_t* attr, clockid_t* clock) {
*clock = COND_GET_CLOCK(*attr);
return 0;
}
int pthread_condattr_setclock(pthread_condattr_t* attr, clockid_t clock) {
if (clock != CLOCK_MONOTONIC && clock != CLOCK_REALTIME) {
return EINVAL;
}
*attr = COND_SET_CLOCK(*attr, clock);
return 0;
}
int pthread_condattr_destroy(pthread_condattr_t* attr) {
*attr = 0xdeada11d;
return 0;
}
struct pthread_cond_internal_t {
atomic_uint state;
bool process_shared() {
return COND_IS_SHARED(atomic_load_explicit(&state, memory_order_relaxed));
}
bool use_realtime_clock() {
return COND_GET_CLOCK(atomic_load_explicit(&state, memory_order_relaxed)) == CLOCK_REALTIME;
}
#if defined(__LP64__)
char __reserved[44];
#endif
};
static_assert(sizeof(pthread_cond_t) == sizeof(pthread_cond_internal_t),
"pthread_cond_t should actually be pthread_cond_internal_t in implementation.");
// For binary compatibility with old version of pthread_cond_t, we can't use more strict alignment
// than 4-byte alignment.
static_assert(alignof(pthread_cond_t) == 4,
"pthread_cond_t should fulfill the alignment requirement of pthread_cond_internal_t.");
static pthread_cond_internal_t* __get_internal_cond(pthread_cond_t* cond_interface) {
return reinterpret_cast<pthread_cond_internal_t*>(cond_interface);
}
int pthread_cond_init(pthread_cond_t* cond_interface, const pthread_condattr_t* attr) {
pthread_cond_internal_t* cond = __get_internal_cond(cond_interface);
unsigned int init_state = 0;
if (attr != NULL) {
init_state = (*attr & COND_FLAGS_MASK);
}
atomic_init(&cond->state, init_state);
return 0;
}
int pthread_cond_destroy(pthread_cond_t* cond_interface) {
pthread_cond_internal_t* cond = __get_internal_cond(cond_interface);
atomic_store_explicit(&cond->state, 0xdeadc04d, memory_order_relaxed);
return 0;
}
// This function is used by pthread_cond_broadcast and
// pthread_cond_signal to atomically decrement the counter
// then wake up thread_count threads.
static int __pthread_cond_pulse(pthread_cond_internal_t* cond, int thread_count) {
// We don't use a release/seq_cst fence here. Because pthread_cond_wait/signal can't be
// used as a method for memory synchronization by itself. It should always be used with
// pthread mutexes. Note that Spurious wakeups from pthread_cond_wait/timedwait may occur,
// so when using condition variables there is always a boolean predicate involving shared
// variables associated with each condition wait that is true if the thread should proceed.
// If the predicate is seen true before a condition wait, pthread_cond_wait/timedwait will
// not be called. That's why pthread_wait/signal pair can't be used as a method for memory
// synchronization. And it doesn't help even if we use any fence here.
// The increase of value should leave flags alone, even if the value can overflows.
atomic_fetch_add_explicit(&cond->state, COND_COUNTER_STEP, memory_order_relaxed);
__futex_wake_ex(&cond->state, cond->process_shared(), thread_count);
return 0;
}
static int __pthread_cond_timedwait(pthread_cond_internal_t* cond, pthread_mutex_t* mutex,
bool use_realtime_clock, const timespec* abs_timeout_or_null) {
int result = check_timespec(abs_timeout_or_null, true);
if (result != 0) {
return result;
}
unsigned int old_state = atomic_load_explicit(&cond->state, memory_order_relaxed);
pthread_mutex_unlock(mutex);
int status = __futex_wait_ex(&cond->state, cond->process_shared(), old_state,
use_realtime_clock, abs_timeout_or_null);
pthread_mutex_lock(mutex);
if (status == -ETIMEDOUT) {
return ETIMEDOUT;
}
return 0;
}
int pthread_cond_broadcast(pthread_cond_t* cond_interface) {
return __pthread_cond_pulse(__get_internal_cond(cond_interface), INT_MAX);
}
int pthread_cond_signal(pthread_cond_t* cond_interface) {
return __pthread_cond_pulse(__get_internal_cond(cond_interface), 1);
}
int pthread_cond_wait(pthread_cond_t* cond_interface, pthread_mutex_t* mutex) {
pthread_cond_internal_t* cond = __get_internal_cond(cond_interface);
return __pthread_cond_timedwait(cond, mutex, false, nullptr);
}
int pthread_cond_timedwait(pthread_cond_t *cond_interface, pthread_mutex_t * mutex,
const timespec *abstime) {
pthread_cond_internal_t* cond = __get_internal_cond(cond_interface);
return __pthread_cond_timedwait(cond, mutex, cond->use_realtime_clock(), abstime);
}
#if !defined(__LP64__)
// TODO: this exists only for backward binary compatibility on 32 bit platforms.
extern "C" int pthread_cond_timedwait_monotonic(pthread_cond_t* cond_interface,
pthread_mutex_t* mutex,
const timespec* abs_timeout) {
return __pthread_cond_timedwait(__get_internal_cond(cond_interface), mutex, false, abs_timeout);
}
extern "C" int pthread_cond_timedwait_monotonic_np(pthread_cond_t* cond_interface,
pthread_mutex_t* mutex,
const timespec* abs_timeout) {
return pthread_cond_timedwait_monotonic(cond_interface, mutex, abs_timeout);
}
// Force this function using CLOCK_MONOTONIC because it was always using
// CLOCK_MONOTONIC in history.
extern "C" int pthread_cond_timedwait_relative_np(pthread_cond_t* cond_interface,
pthread_mutex_t* mutex,
const timespec* rel_timeout) {
timespec ts;
timespec* abs_timeout = nullptr;
if (rel_timeout != nullptr) {
absolute_timespec_from_timespec(ts, *rel_timeout, CLOCK_MONOTONIC);
abs_timeout = &ts;
}
return __pthread_cond_timedwait(__get_internal_cond(cond_interface), mutex, false, abs_timeout);
}
extern "C" int pthread_cond_timeout_np(pthread_cond_t* cond_interface,
pthread_mutex_t* mutex, unsigned ms) {
timespec ts;
timespec_from_ms(ts, ms);
return pthread_cond_timedwait_relative_np(cond_interface, mutex, &ts);
}
#endif // !defined(__LP64__)

38
libc/bionic/bionic_time_conversions.cpp → libc/bionic/pthread_cond_timedwait.cpp
View file

@ -1,5 +1,5 @@
/*
* Copyright (C) 2013 The Android Open Source Project
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -26,28 +26,26 @@
* SUCH DAMAGE.
*/
#include "private/bionic_time_conversions.h"
#include <pthread.h>
#include <dlfcn.h>
#include "private/bionic_constants.h"
#include <errno.h>
#include <time.h>
bool timespec_from_timeval(timespec& ts, const timeval& tv) {
// Whole seconds can just be copied.
ts.tv_sec = tv.tv_sec;
// From bionic_constants.h
#define NS_PER_S 1000000000
// But we might overflow when converting microseconds to nanoseconds.
if (tv.tv_usec >= 1000000 || tv.tv_usec < 0) {
return false;
int pthread_cond_timedwait(pthread_cond_t *cond_interface, pthread_mutex_t * mutex,
const timespec *abstime) {
// HAX: Timespec checks are failing if tv_nsec >= 1000000000L (aka 1 sec).
// Increment tv_sec while subtracting NS_PER_S from tv_nsec till tv_nsec is
// < 1000000000L such that tv_nsec doesn't overflow and passes check_timespec().
while (abstime->tv_nsec >= NS_PER_S) {
const_cast<timespec*>(abstime)->tv_nsec -= NS_PER_S;
const_cast<timespec*>(abstime)->tv_sec++;
}
ts.tv_nsec = tv.tv_usec * 1000;
return true;
}
void timespec_from_ms(timespec& ts, const int ms) {
ts.tv_sec = ms / 1000;
ts.tv_nsec = (ms % 1000) * 1000000;
}
void timeval_from_timespec(timeval& tv, const timespec& ts) {
tv.tv_sec = ts.tv_sec;
tv.tv_usec = ts.tv_nsec / 1000;
int (*real_pthread_cond_timedwait)(pthread_cond_t*, pthread_mutex_t*, const timespec*);
*(void **)&real_pthread_cond_timedwait = dlsym(RTLD_NEXT, "pthread_cond_timedwait");
return real_pthread_cond_timedwait(cond_interface, mutex, abstime);
}

22
libc/private/bionic_constants.h
View file

@ -1,22 +0,0 @@
/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef _BIONIC_CONSTANTS_H_
#define _BIONIC_CONSTANTS_H_
#define NS_PER_S 1000000000
#endif // _BIONIC_CONSTANTS_H_

77
libc/private/bionic_futex.h
View file

@ -1,77 +0,0 @@
/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _BIONIC_FUTEX_H
#define _BIONIC_FUTEX_H
#include <errno.h>
#include <linux/futex.h>
#include <stdbool.h>
#include <stddef.h>
#include <sys/cdefs.h>
#include <sys/syscall.h>
#include <unistd.h>
__BEGIN_DECLS
struct timespec;
static inline __always_inline int __futex(volatile void* ftx, int op, int value,
const struct timespec* timeout,
int bitset) {
// Our generated syscall assembler sets errno, but our callers (pthread functions) don't want to.
int saved_errno = errno;
int result = syscall(__NR_futex, ftx, op, value, timeout, NULL, bitset);
if (__predict_false(result == -1)) {
result = -errno;
errno = saved_errno;
}
return result;
}
static inline int __futex_wake(volatile void* ftx, int count) {
return __futex(ftx, FUTEX_WAKE, count, NULL, 0);
}
static inline int __futex_wake_ex(volatile void* ftx, bool shared, int count) {
return __futex(ftx, shared ? FUTEX_WAKE : FUTEX_WAKE_PRIVATE, count, NULL, 0);
}
static inline int __futex_wait(volatile void* ftx, int value, const struct timespec* timeout) {
return __futex(ftx, FUTEX_WAIT, value, timeout, 0);
}
static inline int __futex_wait_ex(volatile void* ftx, bool shared, int value,
bool use_realtime_clock, const struct timespec* abs_timeout) {
return __futex(ftx, (shared ? FUTEX_WAIT_BITSET : FUTEX_WAIT_BITSET_PRIVATE) |
(use_realtime_clock ? FUTEX_CLOCK_REALTIME : 0), value, abs_timeout,
FUTEX_BITSET_MATCH_ANY);
}
__END_DECLS
#endif /* _BIONIC_FUTEX_H */

83
libc/private/bionic_time_conversions.h
View file

@ -1,83 +0,0 @@
/*
* Copyright (C) 2013 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _BIONIC_TIME_CONVERSIONS_H
#define _BIONIC_TIME_CONVERSIONS_H
#include <errno.h>
#include <time.h>
#include <sys/cdefs.h>
#include "private/bionic_constants.h"
__BEGIN_DECLS
__LIBC_HIDDEN__ bool timespec_from_timeval(timespec& ts, const timeval& tv);
__LIBC_HIDDEN__ void timespec_from_ms(timespec& ts, const int ms);
__LIBC_HIDDEN__ void timeval_from_timespec(timeval& tv, const timespec& ts);
__END_DECLS
static inline int check_timespec(const timespec* ts, bool null_allowed) {
if (null_allowed && ts == nullptr) {
return 0;
}
#if 1
// HAX: Timespec checks are failing if tv_nsec < 1000000000L (aka 1 sec).
// Take out each second from tv_nsec and add them to tv_sec till tv_nsec is
// < 1000000000L such that tv_nsec doesn't overflow and passes check_timespec().
while (ts->tv_nsec >= NS_PER_S) {
const_cast<timespec*>(ts)->tv_nsec -= NS_PER_S;
const_cast<timespec*>(ts)->tv_sec += 1;
}
#endif
// glibc just segfaults if you pass a null timespec.
// That seems a lot more likely to catch bad code than returning EINVAL.
if (ts->tv_nsec < 0 || ts->tv_nsec >= NS_PER_S) {
return EINVAL;
}
if (ts->tv_sec < 0) {
return ETIMEDOUT;
}
return 0;
}
#if !defined(__LP64__)
static inline void absolute_timespec_from_timespec(timespec& abs_ts, const timespec& ts, clockid_t clock) {
clock_gettime(clock, &abs_ts);
abs_ts.tv_sec += ts.tv_sec;
abs_ts.tv_nsec += ts.tv_nsec;
if (abs_ts.tv_nsec >= NS_PER_S) {
abs_ts.tv_nsec -= NS_PER_S;
abs_ts.tv_sec++;
}
}
#endif
#endif