| [1] | 1 | /* |
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| 2 | * remote_rwlock.h - kernel remote_rwlock definition. |
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| 3 | * |
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| [436] | 4 | * Authors Alain Greiner (2016,2017,2018) |
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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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| 24 | #ifndef _REMOTE_RWLOCK_H_ |
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| 25 | #define _REMOTE_RWLOCK_H_ |
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| 26 | |
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| [14] | 27 | #include <kernel_config.h> |
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| [1] | 28 | #include <hal_types.h> |
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| 29 | #include <xlist.h> |
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| 30 | |
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| 31 | /*************************************************************************************** |
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| [23] | 32 | * This file defines a remote kernel lock, that supports several simultaneous read |
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| [1] | 33 | * accesses, but only one write access. It implements a ticket based allocation policy. |
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| 34 | * It can be used to synchronize threads running in different clusters, because |
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| 35 | * all access functions use remote pointers. |
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| 36 | * - A reader take the lock to atomically increments the registered readers count. |
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| 37 | * Then it release the lock and access the protected structure. It atomically |
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| 38 | * decrements the readers count without taking the lock when access is completed. |
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| 39 | * - A writer take the lock and keep it, but must wait completion of all current read |
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| 40 | * accesses before starting its own access. |
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| 41 | * When the lock is taken by another thread, the new-comers use a busy waiting policy. |
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| 42 | **************************************************************************************/ |
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| 43 | |
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| 44 | typedef struct remote_rwlock_s |
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| 45 | { |
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| [409] | 46 | uint32_t ticket; /*! first free ticket index */ |
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| 47 | uint32_t current; /*! ticket index of current owner */ |
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| 48 | uint32_t count; /*! current number of reader threads */ |
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| 49 | |
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| [438] | 50 | #if DEBUG_REMOTE_RWLOCKS |
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| [409] | 51 | xptr_t owner; /*! extended pointer on writer thread */ |
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| 52 | xlist_entry_t list; /*! member of list of remote locks taken by owner */ |
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| 53 | #endif |
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| 54 | |
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| [1] | 55 | } |
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| 56 | remote_rwlock_t; |
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| 57 | |
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| 58 | /*************************************************************************************** |
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| 59 | * This function initializes a remote rwlock. |
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| 60 | *************************************************************************************** |
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| 61 | * @ lock_xp : extended pointer on the remote rwlock |
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| 62 | **************************************************************************************/ |
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| 63 | void remote_rwlock_init( xptr_t lock_xp ); |
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| 64 | |
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| 65 | /*************************************************************************************** |
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| 66 | * This blocking function get access to a remote rwlock for a reader. |
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| 67 | * It increments the calling thread locks count when the lock has been taken. |
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| 68 | *************************************************************************************** |
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| 69 | * @ lock_xp : extended pointer on the remote rwlock |
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| 70 | **************************************************************************************/ |
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| 71 | void remote_rwlock_rd_lock( xptr_t lock_xp ); |
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| 72 | |
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| 73 | /*************************************************************************************** |
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| 74 | * This function releases a remote rwlock for a reader. |
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| 75 | * It decrements the calling thread locks count when the lock has been released. |
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| 76 | *************************************************************************************** |
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| 77 | * @ lock_xp : extended pointer on the remote rwlock |
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| 78 | **************************************************************************************/ |
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| 79 | void remote_rwlock_rd_unlock( xptr_t lock_xp ); |
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| 80 | |
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| 81 | /*************************************************************************************** |
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| 82 | * This blocking function get access to a remote rwlock for a writer. |
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| 83 | * It increments the calling thread locks count when the lock has been taken. |
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| 84 | *************************************************************************************** |
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| 85 | * @ lock_xp : extended pointer on the remote rwlock |
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| 86 | **************************************************************************************/ |
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| 87 | void remote_rwlock_wr_lock( xptr_t lock_xp ); |
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| 88 | |
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| 89 | /*************************************************************************************** |
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| 90 | * This function releases a remote rwlock for a writer. |
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| 91 | * It decrements the calling thread locks count when the lock has been released. |
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| 92 | *************************************************************************************** |
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| 93 | * @ lock_xp : extended pointer on the remote rwlock |
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| 94 | **************************************************************************************/ |
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| 95 | void remote_rwlock_wr_unlock( xptr_t lock_xp ); |
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| 96 | |
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| [50] | 97 | /*************************************************************************************** |
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| 98 | * Display the lock state on kernel TTY. |
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| 99 | *************************************************************************************** |
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| 100 | * @ lock_xp : extended pointer on the remote rwlock |
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| 101 | * @ comment : comment to be printed. |
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| 102 | **************************************************************************************/ |
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| 103 | void remote_rwlock_print( xptr_t lock_xp, |
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| 104 | char * comment ); |
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| 105 | |
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| [1] | 106 | #endif |
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