source: trunk/kernel/libk/remote_mutex.h @ 581

Last change on this file since 581 was 581, checked in by alain, 3 years ago

1) Improve the busylock debug infrastructure.
2) introduce a non-distributed, but portable implementation for the pthread_barrier.

File size: 7.1 KB
Line 
1/*
2 * remote_mutex.h -  POSIX mutex definition.
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-MKH; if not, write to the Free Software Foundation,
21 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24#ifndef _REMOTE_MUTEX_H_
25#define _REMOTE_MUTEX_H_
26
27#include <kernel_config.h>
28#include <hal_kernel_types.h>
29#include <xlist.h>
30
31/*****************************************************************************************
32 * This file defines the ALMOS-MKH implementation of an user level POSIX compliant mutex.
33 *
34 * It can be used by muti-threaded user applications to synchronise user threads
35 * running in different clusters.
36 *
37 * A mutex is declared by a given user process as a "pthread_mutex_t" global variable.
38 * This user type is implemented as an unsigned long, but the value is not used by the
39 * kernel. ALMOS-MKH uses only the mutex virtual address as an identifier.
40 * For each user mutex, ALMOS-MKH creates a kernel "remote_mutex_t" structure,
41 * dynamically allocated in the reference cluster by the remote_mutex_create() function,
42 * and destroyed by the remote_mutex_destroy() function, using RPC if the calling thread
43 * is not running in the reference cluster.
44 *
45 * The blocking "remote_mutex_lock()" function implements a descheduling policy when
46 * the lock is already taken by another thread : the calling thread is registered
47 * in a waiting queue, rooted in the mutex structure, and the the calling thread
48 * is blocked on the THREAD_BLOCKED_MUTEX condition.
49 * The "remote_mutex_unlock()" function unblocks the first waiting thread in the queue
50 * without releasing the mutex if queue is not empty.
51 ****************************************************************************************/
52
53/*****************************************************************************************
54 * This structure defines the kernel implementation of an user level mutex.
55 ****************************************************************************************/
56
57typedef struct remote_mutex_s
58{
59    remote_busylock_t  lock;            /*! lock protecting the mutex state             */
60    intptr_t           ident;           /*! mutex identifier (vaddr in user space)      */ 
61    uint32_t           taken;           /*! mutex non allocated if 0                    */
62    xlist_entry_t      list;            /*! member of list of mutex in same process     */
63    xlist_entry_t      root;            /*! root of list of waiting threads             */
64    xptr_t             owner;           /*! extended pointer on owner thread            */
65}
66remote_mutex_t;
67
68/*****************************************************************************************
69 * This function returns an extended pointer on the remote mutex, identified
70 * by its virtual address in a given user process. It makes an associative search,
71 * scanning the list of mutex rooted in the reference process descriptor.
72 *****************************************************************************************
73 * @ ident    : mutex virtual address, used as identifier.
74 * @ returns extended pointer on mutex if success / returns XPTR_NULL if not found.
75 ****************************************************************************************/
76xptr_t remote_mutex_from_ident( intptr_t  ident );
77
78/*****************************************************************************************
79 * This function implements the pthread_mutex_init() syscall.
80 * It allocates memory for the mutex descriptor in the reference cluster for
81 * the calling process, it initializes the mutex state, and register it in the
82 * list of mutex owned by the reference process.
83 *****************************************************************************************
84 * @ ident       : mutex identifier (virtual address in user space).
85 * @ return 0 if success / ENOMEM if no memory / EINVAL if invalid argument.
86 ****************************************************************************************/
87error_t remote_mutex_create( intptr_t ident );
88
89/*****************************************************************************************
90 * This function implements the pthread_mutex_destroy() syscall.
91 * It releases thr memory allocated for the mutex descriptor, and remove the mutex
92 * from the list of mutex owned by the reference process.
93 *****************************************************************************************
94 * @ mutex_xp  : extended pointer on mutex descriptor.
95 ****************************************************************************************/
96void remote_mutex_destroy( xptr_t  mutex_xp );
97
98/*****************************************************************************************
99 * This blocking function implements the pthread_mutex_lock() syscall.
100 * It returns only when the ownership of the mutex identified by the <mutex_xp>
101 * argument has been obtained by the calling thread. It register in the mutex waiting
102 * queue when the mutex is already taken by another thread.
103 *****************************************************************************************
104 * @ mutex_xp  : extended pointer on mutex descriptor.
105 ****************************************************************************************/
106void remote_mutex_lock( xptr_t  mutex_xp );
107
108/*****************************************************************************************
109 * This function implements the pthread_mutex_unlock() syscall.
110 * It cheks that the calling thread is actually the mutex owner.
111 * It reset the "taken" & "owner" fields for the mutex identified by <mutex_xp>.
112 * It unblocks the first thread registered in the mutex waiting queue, when the
113 * queue is not empty.
114 *****************************************************************************************
115 * @ mutex_xp  : extended pointer on mutex descriptor.
116 * @ return 0 if success / return non zero if calling thread is not mutex owner.
117 ****************************************************************************************/
118error_t remote_mutex_unlock( xptr_t  mutex_xp );
119
120/*****************************************************************************************
121 * This non blocking function function attempts to lock a mutex without blocking.
122 *****************************************************************************************
123 * @ mutex_xp  : extended pointer on mutex descriptor.
124 * @ return 0 if success / return non zero if already taken.
125 ****************************************************************************************/
126error_t remote_mutex_trylock( xptr_t  mutex_xp );
127
128
129
130#endif
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