| [563] | 1 | /* |
|---|
| 2 | * queuelock.h: local kernel lock with waiting queue implementation. |
|---|
| 3 | * |
|---|
| 4 | * Authors Alain Greiner (2016,2017,2018) |
|---|
| 5 | * |
|---|
| 6 | * Copyright (c) UPMC Sorbonne Universites |
|---|
| 7 | * |
|---|
| 8 | * This file is part of ALMOS-MKH. |
|---|
| 9 | * |
|---|
| 10 | * ALMOS-MKH is free software; you can redistribute it and/or modify it |
|---|
| 11 | * under the terms of the GNU General Public License as published by |
|---|
| 12 | * the Free Software Foundation; version 2.0 of the License. |
|---|
| 13 | * |
|---|
| 14 | * ALMOS-MKH is distributed in the hope that it will be useful, but |
|---|
| 15 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
|---|
| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
|---|
| 17 | * General Public License for more details. |
|---|
| 18 | * |
|---|
| 19 | * You should have received a copy of the GNU General Public License |
|---|
| 20 | * along with ALMOS-kernel; if not, write to the Free Software Foundation, |
|---|
| 21 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
|---|
| 22 | */ |
|---|
| 23 | |
|---|
| 24 | #ifndef _QUEUELOCK_H_ |
|---|
| 25 | #define _QUEUELOCK_H_ |
|---|
| 26 | |
|---|
| 27 | #include <kernel_config.h> |
|---|
| 28 | #include <hal_kernel_types.h> |
|---|
| 29 | #include <busylock.h> |
|---|
| 30 | #include <list.h> |
|---|
| 31 | |
|---|
| 32 | /******************************************************************************************* |
|---|
| 33 | * This synchronisation object sequencializes concurrent read or write accesses to a |
|---|
| 34 | * locally shared object in a given cluster (i.e. made by thread(s) running in same cluster. |
|---|
| 35 | * This lock has only two states: taken or free. |
|---|
| 36 | * When the lock has been taken by another thread T', the thread T executing the |
|---|
| 37 | * queuelock_acquire() function blocks and deschedules, after registering in the waiting |
|---|
| 38 | * queue rooted in lock descriptor. The first thread in the waiting queue will be unblocked |
|---|
| 39 | * by the owner thread executing the queuelock_release() function. |
|---|
| 40 | * To handle concurrent accesses between a thread T executing the acquire() function |
|---|
| 41 | * and a thread T' executing the release() function, the "queuelock" is protected |
|---|
| 42 | * by a "busylock" used by these two access functions. |
|---|
| 43 | * WARNING: this queuelock is NOT registered in the thread "local_locks" field. |
|---|
| 44 | ******************************************************************************************/ |
|---|
| 45 | |
|---|
| 46 | |
|---|
| 47 | /******************************************************************************************* |
|---|
| 48 | * This structure defines a queuelock. |
|---|
| 49 | ******************************************************************************************/ |
|---|
| 50 | |
|---|
| 51 | typedef struct queuelock_s |
|---|
| 52 | { |
|---|
| 53 | busylock_t lock; /*! protect atomic access to queuelock */ |
|---|
| 54 | volatile uint32_t taken; /*! state : free if zero / taken if non zero */ |
|---|
| 55 | list_entry_t root; /*! root of list of locally waiting threads */ |
|---|
| 56 | } |
|---|
| 57 | queuelock_t; |
|---|
| 58 | |
|---|
| 59 | /******************************************************************************************* |
|---|
| 60 | * This function initializes a local queuelock in free state. |
|---|
| 61 | * The <type> argument defines the lock usage and is only used for debug. |
|---|
| 62 | * This type is actually stored in the associated busylock descriptor. |
|---|
| 63 | ******************************************************************************************* |
|---|
| 64 | * @ lock : local pointer on queuelock. |
|---|
| 65 | * @ type : lock usage for debug. |
|---|
| 66 | ******************************************************************************************/ |
|---|
| 67 | inline void queuelock_init( queuelock_t * lock, |
|---|
| 68 | uint32_t type ); |
|---|
| 69 | |
|---|
| 70 | /******************************************************************************************* |
|---|
| 71 | * This blocking function acquires a queuelock. |
|---|
| 72 | * The calling thread and the lock must be in same cluster. |
|---|
| 73 | * It uses the busylock to atomically access/update the queuelock state. |
|---|
| 74 | * If the lock is already taken, the calling thread atomically registers in the list |
|---|
| 75 | * of waiting threads (rooted in the lock descriptor), block and deschedule. |
|---|
| 76 | ******************************************************************************************* |
|---|
| 77 | * @ lock : local pointer on queuelock. |
|---|
| 78 | ******************************************************************************************/ |
|---|
| 79 | void queuelock_acquire( queuelock_t * lock ); |
|---|
| 80 | |
|---|
| 81 | /******************************************************************************************* |
|---|
| 82 | * This function releases a queuelock. |
|---|
| 83 | * The calling thread and the lock must be in same cluster. |
|---|
| 84 | * It uses the busylock to atomically access/update the queuelock state. |
|---|
| 85 | * If the list of waiting threads is not empty, the first waiting thread is unblocked. |
|---|
| 86 | ******************************************************************************************* |
|---|
| 87 | * @ lock : local pointer on queuelock. |
|---|
| 88 | ******************************************************************************************/ |
|---|
| 89 | void queuelock_release( queuelock_t * lock ); |
|---|
| 90 | |
|---|
| 91 | |
|---|
| 92 | #endif /* _QUEUELOCK_H_ */ |
|---|
