[1] | 1 | /* |
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[563] | 2 | * rwlock.c - kernel local read/write lock implementation. |
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[1] | 3 | * |
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[629] | 4 | * Author Alain Greiner (2016,2017,2018,2019) |
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[1] | 5 | * |
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| 6 | * Copyright (c) UPMC Sorbonne Universites |
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| 7 | * |
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| 8 | * This file is part of ALMOS-MKH. |
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| 9 | * |
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| 10 | * ALMOS-MKH is free software; you can redistribute it and/or modify it |
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| 11 | * under the terms of the GNU General Public License as published by |
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| 12 | * the Free Software Foundation; version 2.0 of the License. |
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| 13 | * |
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| 14 | * ALMOS-MKH is distributed in the hope that it will be useful, but |
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| 15 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 17 | * General Public License for more details. |
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| 18 | * |
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| 19 | * You should have received a copy of the GNU General Public License |
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| 20 | * along with ALMOS-MKH; if not, write to the Free Software Foundation, |
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| 21 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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| 22 | */ |
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| 23 | |
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[14] | 24 | #include <kernel_config.h> |
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[457] | 25 | #include <hal_kernel_types.h> |
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[1] | 26 | #include <hal_atomic.h> |
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| 27 | #include <hal_special.h> |
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| 28 | #include <hal_irqmask.h> |
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| 29 | #include <thread.h> |
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| 30 | #include <printk.h> |
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| 31 | #include <rwlock.h> |
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| 32 | |
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[563] | 33 | ////////////////////////////////////////////////////////////////////////////// |
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| 34 | // Extern global variables |
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| 35 | ////////////////////////////////////////////////////////////////////////////// |
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| 36 | |
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| 37 | extern char * lock_type_str[]; // allocated in kernel_init.c |
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| 38 | |
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| 39 | |
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| 40 | ////////////////////////////////// |
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| 41 | void rwlock_init( rwlock_t * lock, |
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| 42 | uint32_t type ) |
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[1] | 43 | { |
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[563] | 44 | lock->taken = 0; |
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[1] | 45 | lock->count = 0; |
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[409] | 46 | |
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[563] | 47 | list_root_init( &lock->rd_root ); |
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| 48 | list_root_init( &lock->wr_root ); |
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[409] | 49 | |
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[563] | 50 | busylock_init( &lock->lock , type ); |
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[603] | 51 | |
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[610] | 52 | #if DEBUG_RWLOCK_TYPE |
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[603] | 53 | thread_t * this = CURRENT_THREAD; |
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[666] | 54 | bool_t cond = (lock_type == DEBUG_RWLOCK_TYPE) && |
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| 55 | (((local_cxy == (cxt_t)DEBUG_RWLOCK_CXY) && |
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| 56 | (lock == (rwlock_t*)DEBUG_RWLOCK_PTR)) || |
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| 57 | ((DEBUG_RWLOCK_CXY == 0) && |
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| 58 | (DEBUG_RWLOCK_PTR == 0))); |
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| 59 | if( cond ) printk("\n[%s] thread[%x,%x] initialise lock %s [%x,%x]\n", |
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[603] | 60 | __FUNCTION__, this->process->pid, this->trdid, |
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| 61 | lock_type_str[type], local_cxy, lock ); |
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| 62 | #endif |
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| 63 | |
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[1] | 64 | } |
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| 65 | |
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[563] | 66 | ///////////////////////////////////////// |
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| 67 | void rwlock_rd_acquire( rwlock_t * lock ) |
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[1] | 68 | { |
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[563] | 69 | thread_t * this = CURRENT_THREAD; |
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[1] | 70 | |
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[563] | 71 | // check calling thread can yield |
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| 72 | thread_assert_can_yield( this , __FUNCTION__ ); |
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[1] | 73 | |
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[563] | 74 | // get busylock |
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| 75 | busylock_acquire( &lock->lock ); |
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| 76 | |
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[623] | 77 | #if DEBUG_RWLOCK_TYPE |
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[666] | 78 | uint32_t lock_type = lock->lock.type; |
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| 79 | bool_t cond = (lock_type == DEBUG_RWLOCK_TYPE) && |
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| 80 | (((local_cxy == (cxt_t)DEBUG_RWLOCK_CXY) && |
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| 81 | (lock == (rwlock_t*)DEBUG_RWLOCK_PTR)) || |
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| 82 | ((DEBUG_RWLOCK_CXY == 0) && |
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| 83 | (DEBUG_RWLOCK_PTR == 0))); |
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[623] | 84 | #endif |
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| 85 | |
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[563] | 86 | // block and deschedule if lock already taken |
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| 87 | while( lock->taken ) |
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[1] | 88 | { |
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[563] | 89 | |
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[610] | 90 | #if DEBUG_RWLOCK_TYPE |
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[666] | 91 | if( cond ) |
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[603] | 92 | printk("\n[%s] thread[%x,%x] READ BLOCK on rwlock %s [%x,%x] / taken %d / count %d\n", |
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[600] | 93 | __FUNCTION__, this->process->pid, this->trdid, |
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[610] | 94 | lock_type_str[lock_type], local_cxy, lock, lock->taken, lock->count ); |
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[563] | 95 | #endif |
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| 96 | // register reader thread in waiting queue |
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| 97 | list_add_last( &lock->rd_root , &this->wait_list ); |
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| 98 | |
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| 99 | // block reader thread |
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| 100 | thread_block( XPTR( local_cxy , this ) , THREAD_BLOCKED_LOCK ); |
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| 101 | |
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| 102 | // release busylock |
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| 103 | busylock_release( &lock->lock ); |
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| 104 | |
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| 105 | // deschedule |
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| 106 | sched_yield("reader wait rwlock"); |
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| 107 | |
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| 108 | // get busylock |
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| 109 | busylock_acquire( &lock->lock ); |
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[1] | 110 | } |
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| 111 | |
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[603] | 112 | // increment number of readers |
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| 113 | lock->count++; |
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| 114 | |
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[610] | 115 | #if DEBUG_RWLOCK_TYPE |
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[666] | 116 | if( cond ) |
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[603] | 117 | printk("\n[%s] thread[%x,%x] READ ACQUIRE rwlock %s [%x,%x] / taken %d / count %d\n", |
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[600] | 118 | __FUNCTION__, this->process->pid, this->trdid, |
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[610] | 119 | lock_type_str[lock_type], local_cxy, lock, lock->taken, lock->count ); |
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[563] | 120 | #endif |
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[1] | 121 | |
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[563] | 122 | // release busylock |
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| 123 | busylock_release( &lock->lock ); |
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[409] | 124 | |
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[563] | 125 | } // end rwlock_rd_acquire() |
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[1] | 126 | |
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[563] | 127 | ///////////////////////////////////////// |
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| 128 | void rwlock_wr_acquire( rwlock_t * lock ) |
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| 129 | { |
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| 130 | thread_t * this = CURRENT_THREAD; |
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[1] | 131 | |
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[563] | 132 | // check calling thread can yield |
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| 133 | thread_assert_can_yield( this , __FUNCTION__ ); |
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[1] | 134 | |
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[563] | 135 | // get busylock |
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| 136 | busylock_acquire( &lock->lock ); |
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[1] | 137 | |
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[623] | 138 | #if DEBUG_RWLOCK_TYPE |
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[666] | 139 | uint32_t lock_type = lock->lock.type; |
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| 140 | bool_t cond = (lock_type == DEBUG_RWLOCK_TYPE) && |
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| 141 | (((local_cxy == (cxt_t)DEBUG_RWLOCK_CXY) && |
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| 142 | (lock == (rwlock_t*)DEBUG_RWLOCK_PTR)) || |
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| 143 | ((DEBUG_RWLOCK_CXY == 0) && |
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| 144 | (DEBUG_RWLOCK_PTR == 0))); |
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[623] | 145 | #endif |
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| 146 | |
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[563] | 147 | // block and deschedule if lock already taken or existing read access |
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| 148 | while( lock->taken || lock->count ) |
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| 149 | { |
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| 150 | |
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[610] | 151 | #if DEBUG_RWLOCK_TYPE |
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[666] | 152 | if( cond ) |
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[603] | 153 | printk("\n[%s] thread[%x,%x] WRITE BLOCK on rwlock %s [%x,%x] / taken %d / count %d\n", |
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[600] | 154 | __FUNCTION__, this->process->pid, this->trdid, |
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[610] | 155 | lock_type_str[lock_type], local_cxy, lock, lock->taken, lock->count ); |
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[563] | 156 | #endif |
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| 157 | // register writer in waiting queue |
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| 158 | list_add_last( &lock->wr_root , &this->wait_list ); |
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[1] | 159 | |
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[603] | 160 | // block writer thread |
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[563] | 161 | thread_block( XPTR( local_cxy , this ) , THREAD_BLOCKED_LOCK ); |
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| 162 | |
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| 163 | // release busylock |
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| 164 | busylock_release( &lock->lock ); |
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| 165 | |
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| 166 | // deschedule |
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| 167 | sched_yield("writer wait rwlock"); |
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| 168 | |
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| 169 | // get busylock |
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| 170 | busylock_acquire( &lock->lock ); |
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| 171 | } |
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| 172 | |
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[603] | 173 | // take the rwlock |
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| 174 | lock->taken = 1; |
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| 175 | |
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[610] | 176 | #if DEBUG_RWLOCK_TYPE |
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[666] | 177 | if( cond ) |
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[603] | 178 | printk("\n[%s] thread[%x,%x] WRITE ACQUIRE rwlock %s [%x,%x] / taken %d / count %d\n", |
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[600] | 179 | __FUNCTION__, this->process->pid, this->trdid, |
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[610] | 180 | lock_type_str[lock_type], local_cxy, lock, lock->taken, lock->count ); |
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[409] | 181 | #endif |
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| 182 | |
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[563] | 183 | // release busylock |
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| 184 | busylock_release( &lock->lock ); |
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| 185 | |
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| 186 | } // end rwlock_wr_acquire() |
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| 187 | |
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| 188 | ///////////////////////////////////////// |
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| 189 | void rwlock_rd_release( rwlock_t * lock ) |
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| 190 | { |
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| 191 | // synchronize memory before lock release |
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| 192 | hal_fence(); |
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| 193 | |
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| 194 | // get busylock |
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| 195 | busylock_acquire( &lock->lock ); |
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| 196 | |
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[603] | 197 | // decrement number of readers |
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| 198 | lock->count--; |
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| 199 | |
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[610] | 200 | #if DEBUG_RWLOCK_TYPE |
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[600] | 201 | thread_t * this = CURRENT_THREAD; |
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[666] | 202 | uint32_t lock_type = lock->lock.type; |
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| 203 | bool_t cond = (lock_type == DEBUG_RWLOCK_TYPE) && |
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| 204 | (((local_cxy == (cxt_t)DEBUG_RWLOCK_CXY) && |
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| 205 | (lock == (rwlock_t*)DEBUG_RWLOCK_PTR)) || |
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| 206 | ((DEBUG_RWLOCK_CXY == 0) && |
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| 207 | (DEBUG_RWLOCK_PTR == 0))); |
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| 208 | #endif |
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| 209 | |
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| 210 | #if DEBUG_RWLOCK_TYPE |
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| 211 | if( cond ) |
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[603] | 212 | printk("\n[%s] thread[%x,%x] READ RELEASE rwlock %s [%x,%x] / taken %d / count %d\n", |
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[600] | 213 | __FUNCTION__, this->process->pid, this->trdid, |
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[610] | 214 | lock_type_str[lock_type], local_cxy, lock, lock->taken, lock->count ); |
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[563] | 215 | #endif |
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[1] | 216 | |
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[563] | 217 | // release first writer in waiting queue if no current readers |
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| 218 | // and writers waiting queue non empty |
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| 219 | if( (lock->count == 0) && (list_is_empty( &lock->wr_root ) == false) ) |
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| 220 | { |
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| 221 | // get first writer thread |
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| 222 | thread_t * thread = LIST_FIRST( &lock->wr_root , thread_t , wait_list ); |
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| 223 | |
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[610] | 224 | #if DEBUG_RWLOCK_TYPE |
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[666] | 225 | if( cond ) |
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[600] | 226 | printk("\n[%s] thread[%x,%x] UNBLOCK thread[%x,%x] / rwlock %s [%x,%x]\n", |
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| 227 | __FUNCTION__, this->process->pid, this->trdid, thread->process->pid, thread->trdid, |
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[610] | 228 | lock_type_str[lock_type], local_cxy, lock ); |
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[563] | 229 | #endif |
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[1] | 230 | |
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[563] | 231 | // remove this waiting thread from waiting list |
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| 232 | list_unlink( &thread->wait_list ); |
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| 233 | |
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| 234 | // unblock this waiting thread |
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| 235 | thread_unblock( XPTR( local_cxy , thread ) , THREAD_BLOCKED_LOCK ); |
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| 236 | } |
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| 237 | // release all readers in waiting queue if writers waiting queue empty |
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| 238 | // and readers waiting queue non empty |
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| 239 | else if( list_is_empty( &lock->wr_root ) && (list_is_empty( &lock->rd_root ) == false) ) |
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[1] | 240 | { |
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[563] | 241 | while( list_is_empty( &lock->rd_root ) == false ) |
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| 242 | { |
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| 243 | // get first reader thread |
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| 244 | thread_t * thread = LIST_FIRST( &lock->wr_root , thread_t , wait_list ); |
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[1] | 245 | |
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[610] | 246 | #if DEBUG_RWLOCK_TYPE |
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[666] | 247 | if( cond ) |
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[600] | 248 | printk("\n[%s] thread[%x,%x] UNBLOCK thread[%x,%x] / rwlock %s [%x,%x]\n", |
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| 249 | __FUNCTION__, this->process->pid, this->trdid, thread->process->pid, thread->trdid, |
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[610] | 250 | lock_type_str[lock_type], local_cxy, lock ); |
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[563] | 251 | #endif |
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| 252 | |
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| 253 | // remove this waiting thread from waiting list |
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| 254 | list_unlink( &thread->wait_list ); |
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[1] | 255 | |
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[563] | 256 | // unblock this waiting thread |
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| 257 | thread_unblock( XPTR( local_cxy , thread ) , THREAD_BLOCKED_LOCK ); |
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| 258 | } |
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[1] | 259 | } |
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| 260 | |
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[563] | 261 | // release busylock |
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| 262 | busylock_release( &lock->lock ); |
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[1] | 263 | |
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[563] | 264 | } // end rwlock_rd_release() |
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| 265 | |
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| 266 | ///////////////////////////////////////// |
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| 267 | void rwlock_wr_release( rwlock_t * lock ) |
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| 268 | { |
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| 269 | // synchronize memory before lock release |
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| 270 | hal_fence(); |
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| 271 | |
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| 272 | // get busylock |
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| 273 | busylock_acquire( &lock->lock ); |
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| 274 | |
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[603] | 275 | // release the rwlock |
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| 276 | lock->taken = 0; |
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| 277 | |
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[610] | 278 | #if DEBUG_RWLOCK_TYPE |
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[600] | 279 | thread_t * this = CURRENT_THREAD; |
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[666] | 280 | uint32_t lock_type = lock->lock.type; |
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| 281 | bool_t cond = (lock_type == DEBUG_RWLOCK_TYPE) && |
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| 282 | (((local_cxy == (cxt_t)DEBUG_RWLOCK_CXY) && |
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| 283 | (lock == (rwlock_t*)DEBUG_RWLOCK_PTR)) || |
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| 284 | ((DEBUG_RWLOCK_CXY == 0) && |
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| 285 | (DEBUG_RWLOCK_PTR == 0))); |
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| 286 | #endif |
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| 287 | |
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| 288 | #if DEBUG_RWLOCK_TYPE |
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| 289 | if( cond ) |
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[603] | 290 | printk("\n[%s] thread[%x,%x] WRITE RELEASE rwlock %s [%x,%x] / taken %d / count %d\n", |
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[600] | 291 | __FUNCTION__, this->process->pid, this->trdid, |
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[610] | 292 | lock_type_str[lock_type], local_cxy, lock, lock->taken, lock->count ); |
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[409] | 293 | #endif |
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| 294 | |
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[563] | 295 | // release first waiting writer thread if writers waiting queue non empty |
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| 296 | if( list_is_empty( &lock->wr_root ) == false ) |
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| 297 | { |
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| 298 | // get first writer thread |
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| 299 | thread_t * thread = LIST_FIRST( &lock->wr_root , thread_t , wait_list ); |
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[1] | 300 | |
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[610] | 301 | #if DEBUG_RWLOCK_TYPE |
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[666] | 302 | if( cond ) |
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[600] | 303 | printk("\n[%s] thread[%x,%x] UNBLOCK thread[%x,%x] / rwlock %s [%x,%x]\n", |
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| 304 | __FUNCTION__, this->process->pid, this->trdid, thread->process->pid, thread->trdid, |
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[610] | 305 | lock_type_str[lock_type], local_cxy, lock ); |
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[409] | 306 | #endif |
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[563] | 307 | // remove this waiting thread from waiting list |
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| 308 | list_unlink( &thread->wait_list ); |
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[409] | 309 | |
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[563] | 310 | // unblock this waiting thread |
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| 311 | thread_unblock( XPTR( local_cxy , thread ) , THREAD_BLOCKED_LOCK ); |
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| 312 | } |
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[337] | 313 | |
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[563] | 314 | // check readers waiting queue and release all if writers waiting queue empty |
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| 315 | else |
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| 316 | { |
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| 317 | while( list_is_empty( &lock->rd_root ) == false ) |
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| 318 | { |
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| 319 | // get first reader thread |
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| 320 | thread_t * thread = LIST_FIRST( &lock->rd_root , thread_t , wait_list ); |
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| 321 | |
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[610] | 322 | #if DEBUG_RWLOCK_TYPE |
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[666] | 323 | if( cond ) |
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[600] | 324 | printk("\n[%s] thread[%x,%x] UNBLOCK thread[%x,%x] / rwlock %s [%x,%x]\n", |
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| 325 | __FUNCTION__, this->process->pid, this->trdid, thread->process->pid, thread->trdid, |
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[610] | 326 | lock_type_str[lock_type], local_cxy, lock ); |
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[563] | 327 | #endif |
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| 328 | // remove this waiting thread from waiting list |
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| 329 | list_unlink( &thread->wait_list ); |
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[1] | 330 | |
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[563] | 331 | // unblock this waiting thread |
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| 332 | thread_unblock( XPTR( local_cxy , thread ) , THREAD_BLOCKED_LOCK ); |
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| 333 | } |
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| 334 | } |
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| 335 | |
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| 336 | // release busylock |
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| 337 | busylock_release( &lock->lock ); |
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| 338 | |
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| 339 | } // end rwlock_wr_release() |
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| 340 | |
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| 341 | |
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