11dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project/* 21dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Copyright (C) 2008 The Android Open Source Project 31dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * All rights reserved. 41dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 51dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Redistribution and use in source and binary forms, with or without 61dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * modification, are permitted provided that the following conditions 71dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * are met: 81dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * * Redistributions of source code must retain the above copyright 91dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * notice, this list of conditions and the following disclaimer. 101dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * * Redistributions in binary form must reproduce the above copyright 111dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * notice, this list of conditions and the following disclaimer in 121dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * the documentation and/or other materials provided with the 131dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * distribution. 141dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 151dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 161dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 171dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 181dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 191dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 201dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 211dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 221dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 231dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 241dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 251dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 261dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * SUCH DAMAGE. 271dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project */ 28d0c884d3595ecca03c3e70de9909c090cd5f9caePierre Peiffer 293e898476c7230b60a0f76968e64ff25f475b48c0Elliott Hughes#include <pthread.h> 303e898476c7230b60a0f76968e64ff25f475b48c0Elliott Hughes 31d0c884d3595ecca03c3e70de9909c090cd5f9caePierre Peiffer#include <errno.h> 32d0c884d3595ecca03c3e70de9909c090cd5f9caePierre Peiffer#include <limits.h> 3384114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes#include <sys/mman.h> 34d0c884d3595ecca03c3e70de9909c090cd5f9caePierre Peiffer#include <unistd.h> 35d0c884d3595ecca03c3e70de9909c090cd5f9caePierre Peiffer 361dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project#include "pthread_internal.h" 37eb847bc8666842a3cfc9c06e8458ad1abebebaf0Elliott Hughes 38eb847bc8666842a3cfc9c06e8458ad1abebebaf0Elliott Hughes#include "private/bionic_atomic_inline.h" 39eb847bc8666842a3cfc9c06e8458ad1abebebaf0Elliott Hughes#include "private/bionic_futex.h" 40eb847bc8666842a3cfc9c06e8458ad1abebebaf0Elliott Hughes#include "private/bionic_tls.h" 411dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 427c0c3793722aea293c45921ef50e4adcdf9645ceMathias Agopianextern void pthread_debug_mutex_lock_check(pthread_mutex_t *mutex); 437c0c3793722aea293c45921ef50e4adcdf9645ceMathias Agopianextern void pthread_debug_mutex_unlock_check(pthread_mutex_t *mutex); 447c0c3793722aea293c45921ef50e4adcdf9645ceMathias Agopian 451dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project/* a mutex is implemented as a 32-bit integer holding the following fields 461dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 471dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * bits: name description 4840eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes * 31-16 tid owner thread's tid (recursive and errorcheck only) 491dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 15-14 type mutex type 5088f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner * 13 shared process-shared flag 5188f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner * 12-2 counter counter of recursive mutexes 521dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 1-0 state lock state (0, 1 or 2) 531dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project */ 541dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 55e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* Convenience macro, creates a mask of 'bits' bits that starts from 56e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * the 'shift'-th least significant bit in a 32-bit word. 57e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 58e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * Examples: FIELD_MASK(0,4) -> 0xf 59e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * FIELD_MASK(16,9) -> 0x1ff0000 60e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 61e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define FIELD_MASK(shift,bits) (((1 << (bits))-1) << (shift)) 62e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 63e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* This one is used to create a bit pattern from a given field value */ 64e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define FIELD_TO_BITS(val,shift,bits) (((val) & ((1 << (bits))-1)) << (shift)) 65e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 66e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* And this one does the opposite, i.e. extract a field's value from a bit pattern */ 67e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define FIELD_FROM_BITS(val,shift,bits) (((val) >> (shift)) & ((1 << (bits))-1)) 68e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 69e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* Mutex state: 70e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 71e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 0 for unlocked 72e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 1 for locked, no waiters 73e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 2 for locked, maybe waiters 74e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 75e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_SHIFT 0 76e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_LEN 2 77e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 78e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_MASK FIELD_MASK(MUTEX_STATE_SHIFT, MUTEX_STATE_LEN) 79e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_FROM_BITS(v) FIELD_FROM_BITS(v, MUTEX_STATE_SHIFT, MUTEX_STATE_LEN) 80e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_TO_BITS(v) FIELD_TO_BITS(v, MUTEX_STATE_SHIFT, MUTEX_STATE_LEN) 81e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 82e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_UNLOCKED 0 /* must be 0 to match __PTHREAD_MUTEX_INIT_VALUE */ 83e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_LOCKED_UNCONTENDED 1 /* must be 1 due to atomic dec in unlock operation */ 84e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_LOCKED_CONTENDED 2 /* must be 1 + LOCKED_UNCONTENDED due to atomic dec */ 85e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 86e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_FROM_BITS(v) FIELD_FROM_BITS(v, MUTEX_STATE_SHIFT, MUTEX_STATE_LEN) 87e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_TO_BITS(v) FIELD_TO_BITS(v, MUTEX_STATE_SHIFT, MUTEX_STATE_LEN) 88e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 89e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_BITS_UNLOCKED MUTEX_STATE_TO_BITS(MUTEX_STATE_UNLOCKED) 90e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_BITS_LOCKED_UNCONTENDED MUTEX_STATE_TO_BITS(MUTEX_STATE_LOCKED_UNCONTENDED) 91e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_BITS_LOCKED_CONTENDED MUTEX_STATE_TO_BITS(MUTEX_STATE_LOCKED_CONTENDED) 92e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 93e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* return true iff the mutex if locked with no waiters */ 94e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_BITS_IS_LOCKED_UNCONTENDED(v) (((v) & MUTEX_STATE_MASK) == MUTEX_STATE_BITS_LOCKED_UNCONTENDED) 95e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 96e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* return true iff the mutex if locked with maybe waiters */ 97e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_BITS_IS_LOCKED_CONTENDED(v) (((v) & MUTEX_STATE_MASK) == MUTEX_STATE_BITS_LOCKED_CONTENDED) 98e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 99e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* used to flip from LOCKED_UNCONTENDED to LOCKED_CONTENDED */ 100e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_STATE_BITS_FLIP_CONTENTION(v) ((v) ^ (MUTEX_STATE_BITS_LOCKED_CONTENDED ^ MUTEX_STATE_BITS_LOCKED_UNCONTENDED)) 101e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 102e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* Mutex counter: 103e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 104e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * We need to check for overflow before incrementing, and we also need to 105e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * detect when the counter is 0 106e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 107e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_COUNTER_SHIFT 2 108e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_COUNTER_LEN 11 109e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_COUNTER_MASK FIELD_MASK(MUTEX_COUNTER_SHIFT, MUTEX_COUNTER_LEN) 110e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 111e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_COUNTER_BITS_WILL_OVERFLOW(v) (((v) & MUTEX_COUNTER_MASK) == MUTEX_COUNTER_MASK) 112e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_COUNTER_BITS_IS_ZERO(v) (((v) & MUTEX_COUNTER_MASK) == 0) 113e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 114e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* Used to increment the counter directly after overflow has been checked */ 115e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_COUNTER_BITS_ONE FIELD_TO_BITS(1,MUTEX_COUNTER_SHIFT,MUTEX_COUNTER_LEN) 116e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 117e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* Returns true iff the counter is 0 */ 118e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_COUNTER_BITS_ARE_ZERO(v) (((v) & MUTEX_COUNTER_MASK) == 0) 1191dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 120e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* Mutex shared bit flag 121e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 122e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * This flag is set to indicate that the mutex is shared among processes. 123e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * This changes the futex opcode we use for futex wait/wake operations 124e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * (non-shared operations are much faster). 125e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 126e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_SHARED_SHIFT 13 127e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_SHARED_MASK FIELD_MASK(MUTEX_SHARED_SHIFT,1) 128e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 129e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* Mutex type: 130e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 131e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * We support normal, recursive and errorcheck mutexes. 132e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 133e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * The constants defined here *cannot* be changed because they must match 134e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * the C library ABI which defines the following initialization values in 135e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * <pthread.h>: 136e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 137e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * __PTHREAD_MUTEX_INIT_VALUE 138e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * __PTHREAD_RECURSIVE_MUTEX_VALUE 139e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * __PTHREAD_ERRORCHECK_MUTEX_INIT_VALUE 140e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 141e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_TYPE_SHIFT 14 142e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_TYPE_LEN 2 143e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_TYPE_MASK FIELD_MASK(MUTEX_TYPE_SHIFT,MUTEX_TYPE_LEN) 144022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner 145e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_TYPE_NORMAL 0 /* Must be 0 to match __PTHREAD_MUTEX_INIT_VALUE */ 146e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_TYPE_RECURSIVE 1 147e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_TYPE_ERRORCHECK 2 148e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 149e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_TYPE_TO_BITS(t) FIELD_TO_BITS(t, MUTEX_TYPE_SHIFT, MUTEX_TYPE_LEN) 150e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 151e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_TYPE_BITS_NORMAL MUTEX_TYPE_TO_BITS(MUTEX_TYPE_NORMAL) 152e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_TYPE_BITS_RECURSIVE MUTEX_TYPE_TO_BITS(MUTEX_TYPE_RECURSIVE) 153e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_TYPE_BITS_ERRORCHECK MUTEX_TYPE_TO_BITS(MUTEX_TYPE_ERRORCHECK) 154e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 155e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* Mutex owner field: 156e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 157e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * This is only used for recursive and errorcheck mutexes. It holds the 15840eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes * tid of the owning thread. Note that this works because the Linux 15940eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes * kernel _only_ uses 16-bit values for tids. 160e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 161e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * More specifically, it will wrap to 10000 when it reaches over 32768 for 162e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * application processes. You can check this by running the following inside 163e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * an adb shell session: 164e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 165e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner OLDPID=$$; 166e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner while true; do 167e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner NEWPID=$(sh -c 'echo $$') 168e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if [ "$NEWPID" -gt 32768 ]; then 169e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner echo "AARGH: new PID $NEWPID is too high!" 170e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner exit 1 171e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner fi 172e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if [ "$NEWPID" -lt "$OLDPID" ]; then 173e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner echo "****** Wrapping from PID $OLDPID to $NEWPID. *******" 174e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner else 175e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner echo -n "$NEWPID!" 176e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner fi 177e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner OLDPID=$NEWPID 178e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner done 179e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 180e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * Note that you can run the same example on a desktop Linux system, 181e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * the wrapping will also happen at 32768, but will go back to 300 instead. 182e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 183e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_OWNER_SHIFT 16 184e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_OWNER_LEN 16 185e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 186e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_OWNER_FROM_BITS(v) FIELD_FROM_BITS(v,MUTEX_OWNER_SHIFT,MUTEX_OWNER_LEN) 187e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner#define MUTEX_OWNER_TO_BITS(v) FIELD_TO_BITS(v,MUTEX_OWNER_SHIFT,MUTEX_OWNER_LEN) 188e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 189e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner/* Convenience macros. 190e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 191e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * These are used to form or modify the bit pattern of a given mutex value 192e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 1931dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 1941dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 1951dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 19688f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner/* a mutex attribute holds the following fields 19788f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner * 19888f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner * bits: name description 19988f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner * 0-3 type type of mutex 20088f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner * 4 shared process-shared flag 20188f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner */ 20288f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner#define MUTEXATTR_TYPE_MASK 0x000f 20388f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner#define MUTEXATTR_SHARED_MASK 0x0010 2041dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 2051dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 2061dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Projectint pthread_mutexattr_init(pthread_mutexattr_t *attr) 2071dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project{ 20839b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes *attr = PTHREAD_MUTEX_DEFAULT; 20939b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes return 0; 2101dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 2111dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 2121dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Projectint pthread_mutexattr_destroy(pthread_mutexattr_t *attr) 2131dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project{ 21439b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes *attr = -1; 21539b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes return 0; 2161dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 2171dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 21839b644a0e270df453c53d6060cd364391bb1c512Elliott Hughesint pthread_mutexattr_gettype(const pthread_mutexattr_t *attr, int *type_p) 2191dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project{ 22039b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes int type = (*attr & MUTEXATTR_TYPE_MASK); 22139b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes 22239b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes if (type < PTHREAD_MUTEX_NORMAL || type > PTHREAD_MUTEX_ERRORCHECK) { 22339b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes return EINVAL; 2241dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } 22539b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes 22639b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes *type_p = type; 22739b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes return 0; 2281dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 2291dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 2301dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Projectint pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type) 2311dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project{ 23239b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes if (type < PTHREAD_MUTEX_NORMAL || type > PTHREAD_MUTEX_ERRORCHECK ) { 23339b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes return EINVAL; 2341dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } 23539b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes 23639b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes *attr = (*attr & ~MUTEXATTR_TYPE_MASK) | type; 23739b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes return 0; 2381dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 2391dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 2401dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project/* process-shared mutexes are not supported at the moment */ 2411dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 2421dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Projectint pthread_mutexattr_setpshared(pthread_mutexattr_t *attr, int pshared) 2431dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project{ 244b7681167cbe91c2bb95cccdc08f75184ed1fb839Mathias Agopian switch (pshared) { 245b7681167cbe91c2bb95cccdc08f75184ed1fb839Mathias Agopian case PTHREAD_PROCESS_PRIVATE: 24688f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner *attr &= ~MUTEXATTR_SHARED_MASK; 24788f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner return 0; 24888f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner 249b7681167cbe91c2bb95cccdc08f75184ed1fb839Mathias Agopian case PTHREAD_PROCESS_SHARED: 250b7681167cbe91c2bb95cccdc08f75184ed1fb839Mathias Agopian /* our current implementation of pthread actually supports shared 251b7681167cbe91c2bb95cccdc08f75184ed1fb839Mathias Agopian * mutexes but won't cleanup if a process dies with the mutex held. 252b7681167cbe91c2bb95cccdc08f75184ed1fb839Mathias Agopian * Nevertheless, it's better than nothing. Shared mutexes are used 253b7681167cbe91c2bb95cccdc08f75184ed1fb839Mathias Agopian * by surfaceflinger and audioflinger. 254b7681167cbe91c2bb95cccdc08f75184ed1fb839Mathias Agopian */ 25588f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner *attr |= MUTEXATTR_SHARED_MASK; 256b7681167cbe91c2bb95cccdc08f75184ed1fb839Mathias Agopian return 0; 257b7681167cbe91c2bb95cccdc08f75184ed1fb839Mathias Agopian } 25888f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner return EINVAL; 2591dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 2601dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 261c3f114037dbf028896310609fd28cf2b3da99c4dElliott Hughesint pthread_mutexattr_getpshared(const pthread_mutexattr_t* attr, int* pshared) { 26239b644a0e270df453c53d6060cd364391bb1c512Elliott Hughes *pshared = (*attr & MUTEXATTR_SHARED_MASK) ? PTHREAD_PROCESS_SHARED : PTHREAD_PROCESS_PRIVATE; 2631dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project return 0; 2641dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 2651dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 266dff7203ee99ccac446b9a1c4371753a5216c6db4Elliott Hughesint pthread_mutex_init(pthread_mutex_t* mutex, const pthread_mutexattr_t* attr) { 267d4e753fea9345c24dcce89531dff9019bef14eb3Elliott Hughes if (__predict_true(attr == NULL)) { 268e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mutex->value = MUTEX_TYPE_BITS_NORMAL; 26988f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner return 0; 270ba9c6f0989ae94778ba2b9f597adc827c9dc81e8David 'Digit' Turner } 27188f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner 272dff7203ee99ccac446b9a1c4371753a5216c6db4Elliott Hughes int value = 0; 273dff7203ee99ccac446b9a1c4371753a5216c6db4Elliott Hughes if ((*attr & MUTEXATTR_SHARED_MASK) != 0) { 27488f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner value |= MUTEX_SHARED_MASK; 275dff7203ee99ccac446b9a1c4371753a5216c6db4Elliott Hughes } 27688f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner 27788f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner switch (*attr & MUTEXATTR_TYPE_MASK) { 27888f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner case PTHREAD_MUTEX_NORMAL: 279e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner value |= MUTEX_TYPE_BITS_NORMAL; 28088f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner break; 28188f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner case PTHREAD_MUTEX_RECURSIVE: 282e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner value |= MUTEX_TYPE_BITS_RECURSIVE; 28388f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner break; 28488f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner case PTHREAD_MUTEX_ERRORCHECK: 285e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner value |= MUTEX_TYPE_BITS_ERRORCHECK; 28688f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner break; 28788f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner default: 28888f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner return EINVAL; 28988f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner } 29088f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner 29188f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner mutex->value = value; 29288f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner return 0; 2931dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 2941dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 2951dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 2961dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project/* 2971dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Lock a non-recursive mutex. 2981dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 2991dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * As noted above, there are three states: 3001dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 0 (unlocked, no contention) 3011dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 1 (locked, no contention) 3021dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 2 (locked, contention) 3031dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 3041dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Non-recursive mutexes don't use the thread-id or counter fields, and the 3051dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * "type" value is zero, so the only bits that will be set are the ones in 3061dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * the lock state field. 3071dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project */ 308624996026b844ff2eba2283f4dc83ec363d85a11Elliott Hughesstatic inline void _normal_lock(pthread_mutex_t* mutex, int shared) { 309e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* convenience shortcuts */ 310e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner const int unlocked = shared | MUTEX_STATE_BITS_UNLOCKED; 311e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner const int locked_uncontended = shared | MUTEX_STATE_BITS_LOCKED_UNCONTENDED; 3128641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio /* 3138641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * The common case is an unlocked mutex, so we begin by trying to 314e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * change the lock's state from 0 (UNLOCKED) to 1 (LOCKED). 315e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * __bionic_cmpxchg() returns 0 if it made the swap successfully. 316e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * If the result is nonzero, this lock is already held by another thread. 3178641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio */ 318e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (__bionic_cmpxchg(unlocked, locked_uncontended, &mutex->value) != 0) { 319e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner const int locked_contended = shared | MUTEX_STATE_BITS_LOCKED_CONTENDED; 3201dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project /* 3218641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * We want to go to sleep until the mutex is available, which 322e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * requires promoting it to state 2 (CONTENDED). We need to 323e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * swap in the new state value and then wait until somebody wakes us up. 3248641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * 325e31bfae2baa96742f998155ee26e56c826a8ce3aDavid 'Digit' Turner * __bionic_swap() returns the previous value. We swap 2 in and 3268641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * see if we got zero back; if so, we have acquired the lock. If 3278641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * not, another thread still holds the lock and we wait again. 3288641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * 3298641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * The second argument to the __futex_wait() call is compared 3308641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * against the current value. If it doesn't match, __futex_wait() 3318641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * returns immediately (otherwise, it sleeps for a time specified 3328641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * by the third argument; 0 means sleep forever). This ensures 3338641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * that the mutex is in state 2 when we go to sleep on it, which 3348641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * guarantees a wake-up call. 3358641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio */ 336624996026b844ff2eba2283f4dc83ec363d85a11Elliott Hughes while (__bionic_swap(locked_contended, &mutex->value) != unlocked) { 337624996026b844ff2eba2283f4dc83ec363d85a11Elliott Hughes __futex_wait_ex(&mutex->value, shared, locked_contended, NULL); 338624996026b844ff2eba2283f4dc83ec363d85a11Elliott Hughes } 3391dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } 340fcd00ebbdf3e7f4e1e7782a65ae10fb0fc03a1aaAndy McFadden ANDROID_MEMBAR_FULL(); 3411dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 3421dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 3431dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project/* 3441dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Release a non-recursive mutex. The caller is responsible for determining 3451dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * that we are in fact the owner of this lock. 3461dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project */ 347624996026b844ff2eba2283f4dc83ec363d85a11Elliott Hughesstatic inline void _normal_unlock(pthread_mutex_t* mutex, int shared) { 348fcd00ebbdf3e7f4e1e7782a65ae10fb0fc03a1aaAndy McFadden ANDROID_MEMBAR_FULL(); 349fcd00ebbdf3e7f4e1e7782a65ae10fb0fc03a1aaAndy McFadden 3508641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio /* 35188f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner * The mutex state will be 1 or (rarely) 2. We use an atomic decrement 352e31bfae2baa96742f998155ee26e56c826a8ce3aDavid 'Digit' Turner * to release the lock. __bionic_atomic_dec() returns the previous value; 3538641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * if it wasn't 1 we have to do some additional work. 3548641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio */ 355e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (__bionic_atomic_dec(&mutex->value) != (shared|MUTEX_STATE_BITS_LOCKED_UNCONTENDED)) { 3561dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project /* 3578641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * Start by releasing the lock. The decrement changed it from 3588641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * "contended lock" to "uncontended lock", which means we still 3598641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * hold it, and anybody who tries to sneak in will push it back 3608641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * to state 2. 3618641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * 3628641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * Once we set it to zero the lock is up for grabs. We follow 3638641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * this with a __futex_wake() to ensure that one of the waiting 3648641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * threads has a chance to grab it. 3658641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * 3668641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * This doesn't cause a race with the swap/wait pair in 3678641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * _normal_lock(), because the __futex_wait() call there will 3688641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * return immediately if the mutex value isn't 2. 3698641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio */ 37088f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner mutex->value = shared; 3718641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio 3728641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio /* 3738641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * Wake up one waiting thread. We don't know which thread will be 3748641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * woken or when it'll start executing -- futexes make no guarantees 3758641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * here. There may not even be a thread waiting. 3768641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * 3778641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * The newly-woken thread will replace the 0 we just set above 3788641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * with 2, which means that when it eventually releases the mutex 3798641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * it will also call FUTEX_WAKE. This results in one extra wake 3808641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * call whenever a lock is contended, but lets us avoid forgetting 3818641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * anyone without requiring us to track the number of sleepers. 3828641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * 3838641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * It's possible for another thread to sneak in and grab the lock 3848641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * between the zero assignment above and the wake call below. If 3858641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * the new thread is "slow" and holds the lock for a while, we'll 3868641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * wake up a sleeper, which will swap in a 2 and then go back to 3878641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * sleep since the lock is still held. If the new thread is "fast", 3888641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * running to completion before we call wake, the thread we 3898641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * eventually wake will find an unlocked mutex and will execute. 3908641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * Either way we have correct behavior and nobody is orphaned on 3918641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio * the wait queue. 3928641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio */ 3936304d8b21891fd0cb7b5a4c25159a3d3b1709d62David 'Digit' Turner __futex_wake_ex(&mutex->value, shared, 1); 3941dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } 3951dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 3961dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 397022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner/* This common inlined function is used to increment the counter of an 398022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * errorcheck or recursive mutex. 399022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * 400022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * For errorcheck mutexes, it will return EDEADLK 401022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * If the counter overflows, it will return EAGAIN 402022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * Otherwise, it atomically increments the counter and returns 0 403022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * after providing an acquire barrier. 404022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * 405022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * mtype is the current mutex type 406022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * mvalue is the current mutex value (already loaded) 407022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * mutex pointers to the mutex. 408022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner */ 409624996026b844ff2eba2283f4dc83ec363d85a11Elliott Hughesstatic inline __always_inline int _recursive_increment(pthread_mutex_t* mutex, int mvalue, int mtype) { 410e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (mtype == MUTEX_TYPE_BITS_ERRORCHECK) { 411022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner /* trying to re-lock a mutex we already acquired */ 412022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner return EDEADLK; 413022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner } 414022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner 415022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner /* Detect recursive lock overflow and return EAGAIN. 416022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner * This is safe because only the owner thread can modify the 417b57db7581cabb98651c4d8940d65c5c404b914adDavid 'Digit' Turner * counter bits in the mutex value. 418022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner */ 419e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (MUTEX_COUNTER_BITS_WILL_OVERFLOW(mvalue)) { 420022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner return EAGAIN; 421022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner } 422022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner 423022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner /* We own the mutex, but other threads are able to change 424b57db7581cabb98651c4d8940d65c5c404b914adDavid 'Digit' Turner * the lower bits (e.g. promoting it to "contended"), so we 425e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * need to use an atomic cmpxchg loop to update the counter. 426b57db7581cabb98651c4d8940d65c5c404b914adDavid 'Digit' Turner */ 427e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner for (;;) { 428e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* increment counter, overflow was already checked */ 429e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner int newval = mvalue + MUTEX_COUNTER_BITS_ONE; 430d4e753fea9345c24dcce89531dff9019bef14eb3Elliott Hughes if (__predict_true(__bionic_cmpxchg(mvalue, newval, &mutex->value) == 0)) { 431e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* mutex is still locked, not need for a memory barrier */ 432e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner return 0; 433e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 434e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* the value was changed, this happens when another thread changes 435e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * the lower state bits from 1 to 2 to indicate contention. This 436e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * cannot change the counter, so simply reload and try again. 437e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 438e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mvalue = mutex->value; 439e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 4401dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 4411dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 44207f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughesint pthread_mutex_lock(pthread_mutex_t* mutex) { 4431543fdf616ddebee7819214437527f380e5c743bElliott Hughes#if !defined(__LP64__) 4441543fdf616ddebee7819214437527f380e5c743bElliott Hughes if (mutex == NULL) { 4451543fdf616ddebee7819214437527f380e5c743bElliott Hughes return EINVAL; 4461543fdf616ddebee7819214437527f380e5c743bElliott Hughes } 4471543fdf616ddebee7819214437527f380e5c743bElliott Hughes#endif 4481543fdf616ddebee7819214437527f380e5c743bElliott Hughes 449a12c54454f3a6132988b68873903f6e9eed7f384Wink Saville int mvalue, mtype, tid, shared; 45040e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 451022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner mvalue = mutex->value; 452022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner mtype = (mvalue & MUTEX_TYPE_MASK); 453022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner shared = (mvalue & MUTEX_SHARED_MASK); 45440e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 455ff03a7aaade5826e3708f6e320d0612d4cdbdb72Brigid Smith /* Handle non-recursive case first */ 456d4e753fea9345c24dcce89531dff9019bef14eb3Elliott Hughes if ( __predict_true(mtype == MUTEX_TYPE_BITS_NORMAL) ) { 457022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner _normal_lock(mutex, shared); 45840e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner return 0; 45940e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner } 46040e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 46140e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner /* Do we already own this recursive or error-check mutex ? */ 46240eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes tid = __get_thread()->tid; 463e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if ( tid == MUTEX_OWNER_FROM_BITS(mvalue) ) 464022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner return _recursive_increment(mutex, mvalue, mtype); 46540e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 466e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* Add in shared state to avoid extra 'or' operations below */ 4676304d8b21891fd0cb7b5a4c25159a3d3b1709d62David 'Digit' Turner mtype |= shared; 46888f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner 469e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* First, if the mutex is unlocked, try to quickly acquire it. 470e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * In the optimistic case where this works, set the state to 1 to 471e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * indicate locked with no contention */ 472e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (mvalue == mtype) { 473e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner int newval = MUTEX_OWNER_TO_BITS(tid) | mtype | MUTEX_STATE_BITS_LOCKED_UNCONTENDED; 474e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (__bionic_cmpxchg(mvalue, newval, &mutex->value) == 0) { 475e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner ANDROID_MEMBAR_FULL(); 476e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner return 0; 47740e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner } 478e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* argh, the value changed, reload before entering the loop */ 479e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mvalue = mutex->value; 480e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 48140e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 482e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner for (;;) { 483e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner int newval; 48440e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 485e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* if the mutex is unlocked, its value should be 'mtype' and 486e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * we try to acquire it by setting its owner and state atomically. 487e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * NOTE: We put the state to 2 since we _know_ there is contention 488e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * when we are in this loop. This ensures all waiters will be 489e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * unlocked. 49040e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner */ 491e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (mvalue == mtype) { 492e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner newval = MUTEX_OWNER_TO_BITS(tid) | mtype | MUTEX_STATE_BITS_LOCKED_CONTENDED; 493e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* TODO: Change this to __bionic_cmpxchg_acquire when we 494e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * implement it to get rid of the explicit memory 495e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * barrier below. 496e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 497d4e753fea9345c24dcce89531dff9019bef14eb3Elliott Hughes if (__predict_false(__bionic_cmpxchg(mvalue, newval, &mutex->value) != 0)) { 498e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mvalue = mutex->value; 499e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner continue; 500e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 501e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner ANDROID_MEMBAR_FULL(); 502e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner return 0; 503e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 504e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 505e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* the mutex is already locked by another thread, if its state is 1 506e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * we will change it to 2 to indicate contention. */ 507e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (MUTEX_STATE_BITS_IS_LOCKED_UNCONTENDED(mvalue)) { 508e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner newval = MUTEX_STATE_BITS_FLIP_CONTENTION(mvalue); /* locked state 1 => state 2 */ 509d4e753fea9345c24dcce89531dff9019bef14eb3Elliott Hughes if (__predict_false(__bionic_cmpxchg(mvalue, newval, &mutex->value) != 0)) { 510e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mvalue = mutex->value; 511e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner continue; 512e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 513e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mvalue = newval; 514e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 515e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 516e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* wait until the mutex is unlocked */ 517e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner __futex_wait_ex(&mutex->value, shared, mvalue, NULL); 51840e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 519e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mvalue = mutex->value; 52040e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner } 521e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* NOTREACHED */ 5221dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 5231dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 52407f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughesint pthread_mutex_unlock(pthread_mutex_t* mutex) { 5251543fdf616ddebee7819214437527f380e5c743bElliott Hughes#if !defined(__LP64__) 5261543fdf616ddebee7819214437527f380e5c743bElliott Hughes if (mutex == NULL) { 5271543fdf616ddebee7819214437527f380e5c743bElliott Hughes return EINVAL; 5281543fdf616ddebee7819214437527f380e5c743bElliott Hughes } 5291543fdf616ddebee7819214437527f380e5c743bElliott Hughes#endif 5301543fdf616ddebee7819214437527f380e5c743bElliott Hughes 531a12c54454f3a6132988b68873903f6e9eed7f384Wink Saville int mvalue, mtype, tid, shared; 532ba9c6f0989ae94778ba2b9f597adc827c9dc81e8David 'Digit' Turner 533022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner mvalue = mutex->value; 534022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner mtype = (mvalue & MUTEX_TYPE_MASK); 535022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner shared = (mvalue & MUTEX_SHARED_MASK); 53640e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 53740e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner /* Handle common case first */ 538d4e753fea9345c24dcce89531dff9019bef14eb3Elliott Hughes if (__predict_true(mtype == MUTEX_TYPE_BITS_NORMAL)) { 539022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner _normal_unlock(mutex, shared); 5408641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio return 0; 541ba9c6f0989ae94778ba2b9f597adc827c9dc81e8David 'Digit' Turner } 54240e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 54340e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner /* Do we already own this recursive or error-check mutex ? */ 54440eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes tid = __get_thread()->tid; 545e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if ( tid != MUTEX_OWNER_FROM_BITS(mvalue) ) 54640e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner return EPERM; 54740e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 548e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* If the counter is > 0, we can simply decrement it atomically. 549e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * Since other threads can mutate the lower state bits (and only the 550e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * lower state bits), use a cmpxchg to do it. 551e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 552e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (!MUTEX_COUNTER_BITS_IS_ZERO(mvalue)) { 553e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner for (;;) { 554e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner int newval = mvalue - MUTEX_COUNTER_BITS_ONE; 555d4e753fea9345c24dcce89531dff9019bef14eb3Elliott Hughes if (__predict_true(__bionic_cmpxchg(mvalue, newval, &mutex->value) == 0)) { 556e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* success: we still own the mutex, so no memory barrier */ 557e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner return 0; 558e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 559e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* the value changed, so reload and loop */ 560e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mvalue = mutex->value; 561e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 56240e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner } 563e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 564e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* the counter is 0, so we're going to unlock the mutex by resetting 565e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * its value to 'unlocked'. We need to perform a swap in order 566e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * to read the current state, which will be 2 if there are waiters 567e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * to awake. 568e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * 569e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * TODO: Change this to __bionic_swap_release when we implement it 570e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * to get rid of the explicit memory barrier below. 571e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 572e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner ANDROID_MEMBAR_FULL(); /* RELEASE BARRIER */ 573e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mvalue = __bionic_swap(mtype | shared | MUTEX_STATE_BITS_UNLOCKED, &mutex->value); 57440e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 57540e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner /* Wake one waiting thread, if any */ 576e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (MUTEX_STATE_BITS_IS_LOCKED_CONTENDED(mvalue)) { 5776304d8b21891fd0cb7b5a4c25159a3d3b1709d62David 'Digit' Turner __futex_wake_ex(&mutex->value, shared, 1); 57888f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner } 57940e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner return 0; 5801dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 5811dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 58207f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughesint pthread_mutex_trylock(pthread_mutex_t* mutex) { 583a12c54454f3a6132988b68873903f6e9eed7f384Wink Saville int mvalue, mtype, tid, shared; 5841dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 585022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner mvalue = mutex->value; 586022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner mtype = (mvalue & MUTEX_TYPE_MASK); 587022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner shared = (mvalue & MUTEX_SHARED_MASK); 5881dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 58940e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner /* Handle common case first */ 590d4e753fea9345c24dcce89531dff9019bef14eb3Elliott Hughes if ( __predict_true(mtype == MUTEX_TYPE_BITS_NORMAL) ) 59140e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner { 592e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if (__bionic_cmpxchg(shared|MUTEX_STATE_BITS_UNLOCKED, 593e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner shared|MUTEX_STATE_BITS_LOCKED_UNCONTENDED, 594e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner &mutex->value) == 0) { 595fcd00ebbdf3e7f4e1e7782a65ae10fb0fc03a1aaAndy McFadden ANDROID_MEMBAR_FULL(); 5968641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio return 0; 597fcd00ebbdf3e7f4e1e7782a65ae10fb0fc03a1aaAndy McFadden } 59840e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 59940e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner return EBUSY; 60040e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner } 60140e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 60240e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner /* Do we already own this recursive or error-check mutex ? */ 60340eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes tid = __get_thread()->tid; 604e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner if ( tid == MUTEX_OWNER_FROM_BITS(mvalue) ) 605022d303116f742cd337852d37547e2ea24d97a25David 'Digit' Turner return _recursive_increment(mutex, mvalue, mtype); 60640e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 607e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner /* Same as pthread_mutex_lock, except that we don't want to wait, and 608e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * the only operation that can succeed is a single cmpxchg to acquire the 609e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner * lock if it is released / not owned by anyone. No need for a complex loop. 610e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner */ 611e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mtype |= shared | MUTEX_STATE_BITS_UNLOCKED; 612e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mvalue = MUTEX_OWNER_TO_BITS(tid) | mtype | MUTEX_STATE_BITS_LOCKED_UNCONTENDED; 61340e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 614d4e753fea9345c24dcce89531dff9019bef14eb3Elliott Hughes if (__predict_true(__bionic_cmpxchg(mtype, mvalue, &mutex->value) == 0)) { 615e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner ANDROID_MEMBAR_FULL(); 616e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner return 0; 617e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 61840e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 619e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner return EBUSY; 6201dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 6211dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 6220e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughesstatic int __pthread_mutex_timedlock(pthread_mutex_t* mutex, const timespec* abs_timeout, clockid_t clock) { 6230e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes timespec ts; 6243f56b7f65adb9ee35cd0f878ca00b92011eec427David 'Digit' Turner 6250e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes int mvalue = mutex->value; 6260e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes int mtype = (mvalue & MUTEX_TYPE_MASK); 6270e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes int shared = (mvalue & MUTEX_SHARED_MASK); 6283f56b7f65adb9ee35cd0f878ca00b92011eec427David 'Digit' Turner 6290e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // Handle common case first. 6300e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (__predict_true(mtype == MUTEX_TYPE_BITS_NORMAL)) { 6310e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes const int unlocked = shared | MUTEX_STATE_BITS_UNLOCKED; 6320e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes const int locked_uncontended = shared | MUTEX_STATE_BITS_LOCKED_UNCONTENDED; 6330e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes const int locked_contended = shared | MUTEX_STATE_BITS_LOCKED_CONTENDED; 6343f56b7f65adb9ee35cd0f878ca00b92011eec427David 'Digit' Turner 6350e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // Fast path for uncontended lock. Note: MUTEX_TYPE_BITS_NORMAL is 0. 6360e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (__bionic_cmpxchg(unlocked, locked_uncontended, &mutex->value) == 0) { 6370e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes ANDROID_MEMBAR_FULL(); 6380e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes return 0; 6390e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 64040e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 6410e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // Loop while needed. 6420e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes while (__bionic_swap(locked_contended, &mutex->value) != unlocked) { 6430e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (__timespec_from_absolute(&ts, abs_timeout, clock) < 0) { 6440e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes return ETIMEDOUT; 6450e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 6460e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes __futex_wait_ex(&mutex->value, shared, locked_contended, &ts); 6470e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 6480e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes ANDROID_MEMBAR_FULL(); 6490e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes return 0; 6500e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 651e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner 6520e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // Do we already own this recursive or error-check mutex? 6530e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes pid_t tid = __get_thread()->tid; 6540e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (tid == MUTEX_OWNER_FROM_BITS(mvalue)) { 6550e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes return _recursive_increment(mutex, mvalue, mtype); 6560e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 6578641833b62e3b319796dc80ea16eb1592c05edf6Fabrice Di Meglio 6580e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // The following implements the same loop as pthread_mutex_lock_impl 6590e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // but adds checks to ensure that the operation never exceeds the 6600e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // absolute expiration time. 6610e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes mtype |= shared; 66240e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 6630e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // First try a quick lock. 6640e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (mvalue == mtype) { 6650e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes mvalue = MUTEX_OWNER_TO_BITS(tid) | mtype | MUTEX_STATE_BITS_LOCKED_UNCONTENDED; 6660e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (__predict_true(__bionic_cmpxchg(mtype, mvalue, &mutex->value) == 0)) { 6670e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes ANDROID_MEMBAR_FULL(); 6680e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes return 0; 6690e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 6700e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes mvalue = mutex->value; 6710e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 6720e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes 6730e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes while (true) { 6740e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // If the value is 'unlocked', try to acquire it directly. 6750e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // NOTE: put state to 2 since we know there is contention. 6760e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (mvalue == mtype) { // Unlocked. 6770e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes mvalue = MUTEX_OWNER_TO_BITS(tid) | mtype | MUTEX_STATE_BITS_LOCKED_CONTENDED; 6780e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (__bionic_cmpxchg(mtype, mvalue, &mutex->value) == 0) { 679fcd00ebbdf3e7f4e1e7782a65ae10fb0fc03a1aaAndy McFadden ANDROID_MEMBAR_FULL(); 68040e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner return 0; 6810e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 6820e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // The value changed before we could lock it. We need to check 6830e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // the time to avoid livelocks, reload the value, then loop again. 6840e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (__timespec_from_absolute(&ts, abs_timeout, clock) < 0) { 6850e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes return ETIMEDOUT; 6860e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 6870e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes 6880e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes mvalue = mutex->value; 6890e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes continue; 69040e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner } 6913f56b7f65adb9ee35cd0f878ca00b92011eec427David 'Digit' Turner 6920e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // The value is locked. If 'uncontended', try to switch its state 6930e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // to 'contented' to ensure we get woken up later. 6940e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (MUTEX_STATE_BITS_IS_LOCKED_UNCONTENDED(mvalue)) { 6950e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes int newval = MUTEX_STATE_BITS_FLIP_CONTENTION(mvalue); 6960e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (__bionic_cmpxchg(mvalue, newval, &mutex->value) != 0) { 6970e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // This failed because the value changed, reload it. 698e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner mvalue = mutex->value; 6990e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } else { 7000e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // This succeeded, update mvalue. 7010e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes mvalue = newval; 7020e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 703e1414aa96bb62057b1a25c6a9ea1797dd38dce59David 'Digit' Turner } 70488f06cd84a70f8a5212cb03272ec2c7cf0017afaDavid 'Digit' Turner 7050e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // Check time and update 'ts'. 7060e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (__timespec_from_absolute(&ts, abs_timeout, clock) < 0) { 7070e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes return ETIMEDOUT; 7080e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 70940e6b822866ee59f7823000384321bb899416cb1David 'Digit' Turner 7100e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // Only wait to be woken up if the state is '2', otherwise we'll 7110e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // simply loop right now. This can happen when the second cmpxchg 7120e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes // in our loop failed because the mutex was unlocked by another thread. 7130e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (MUTEX_STATE_BITS_IS_LOCKED_CONTENDED(mvalue)) { 7140e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (__futex_wait_ex(&mutex->value, shared, mvalue, &ts) == -ETIMEDOUT) { 7150e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes return ETIMEDOUT; 7160e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 7170e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes mvalue = mutex->value; 718ba9c6f0989ae94778ba2b9f597adc827c9dc81e8David 'Digit' Turner } 7190e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 7200e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes /* NOTREACHED */ 721ba9c6f0989ae94778ba2b9f597adc827c9dc81e8David 'Digit' Turner} 722ba9c6f0989ae94778ba2b9f597adc827c9dc81e8David 'Digit' Turner 7230e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes#if !defined(__LP64__) 7240e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughesextern "C" int pthread_mutex_lock_timeout_np(pthread_mutex_t* mutex, unsigned ms) { 7250e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes timespec abs_timeout; 7260e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes clock_gettime(CLOCK_MONOTONIC, &abs_timeout); 7270e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes abs_timeout.tv_sec += ms / 1000; 7280e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes abs_timeout.tv_nsec += (ms % 1000) * 1000000; 7290e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes if (abs_timeout.tv_nsec >= 1000000000) { 7300e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes abs_timeout.tv_sec++; 7310e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes abs_timeout.tv_nsec -= 1000000000; 7320e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 7330e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes 73407f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes int error = __pthread_mutex_timedlock(mutex, &abs_timeout, CLOCK_MONOTONIC); 73507f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes if (error == ETIMEDOUT) { 73607f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes error = EBUSY; 7370e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes } 73807f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes return error; 7390e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes} 7400e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes#endif 7410e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes 7420e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughesint pthread_mutex_timedlock(pthread_mutex_t* mutex, const timespec* abs_timeout) { 7430e714a5b41451e84c5ded93a42c9a4b0a9440691Elliott Hughes return __pthread_mutex_timedlock(mutex, abs_timeout, CLOCK_REALTIME); 7447c0c3793722aea293c45921ef50e4adcdf9645ceMathias Agopian} 7457c0c3793722aea293c45921ef50e4adcdf9645ceMathias Agopian 74607f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughesint pthread_mutex_destroy(pthread_mutex_t* mutex) { 74707f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes // Use trylock to ensure that the mutex is valid and not already locked. 74807f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes int error = pthread_mutex_trylock(mutex); 74907f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes if (error != 0) { 75007f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes return error; 75107f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes } 75207f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes mutex->value = 0xdead10cc; 75307f1ded1399805fa9367f4db2936832b0c22b7a5Elliott Hughes return 0; 7547c0c3793722aea293c45921ef50e4adcdf9645ceMathias Agopian} 755