source: trunk/kernel/syscalls/sys_thread_join.c @ 1

Last change on this file since 1 was 1, checked in by alain, 5 years ago

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1/*
2 * kern/sys_thread_join.c - passive wait on the end of a given thread
3 *
4 * Copyright (c) 2008,2009,2010,2011,2012 Ghassan Almaless
5 * Copyright (c) 2011,2012 UPMC Sorbonne Universites
6 *
7 * This file is part of ALMOS-kernel.
8 *
9 * ALMOS-kernel is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; version 2.0 of the License.
12 *
13 * ALMOS-kernel is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with ALMOS-kernel; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#include <list.h>
24#include <thread.h>
25#include <scheduler.h>
26#include <kmem.h>
27#include <errno.h>
28#include <task.h>
29#include <spinlock.h>
30
31int sys_thread_join (pthread_t tid, void **thread_return)
32{
33        register struct task_s *task;
34        register struct thread_s *this;
35        register struct thread_s *target_th;
36        register uint_t state = 0;
37        void *retval;
38        int err;
39
40        this   = current_thread;
41        task   = this->task;
42        retval = 0;
43
44        if((tid > task->max_order) || 
45           ((thread_return != NULL) && 
46            (NOT_IN_USPACE((uint_t)thread_return + sizeof(void*)))))
47        {
48                err = EINVAL;
49                goto fail_arg;
50        }
51
52        /* try to write to userland address */
53        if(thread_return)
54        {
55                if((err = cpu_copy_to_uspace(thread_return, &retval, sizeof(void *)))) 
56                        goto fail_uspace_ret;
57        }
58
59        spinlock_lock(&task->th_lock);
60        target_th = task->th_tbl[tid];
61
62        if((target_th == NULL)                 ||
63           (target_th->signature != THREAD_ID) || 
64           (target_th->info.attr.key != tid))
65        {
66                err = ESRCH;
67                goto fail_srch;
68        }
69
70        if(target_th == this)
71        {
72                err = EDEADLK;
73                goto fail_deadlock;
74        }
75
76        if(!(thread_isJoinable(target_th)))
77        {
78                err = EINVAL;
79                goto fail_joinable;
80        }
81   
82        spinlock_lock(&target_th->lock);
83   
84        if(target_th->info.join != NULL)
85        {
86                spinlock_unlock(&target_th->lock);
87                err = EINVAL;
88                goto fail_joined;
89        }
90
91        // Get the exit code of the target thread
92        if ((state=wait_queue_isEmpty(&target_th->info.wait_queue)))
93        {
94                target_th->info.join = this;
95                wait_on(&target_th->info.wait_queue, WAIT_ANY);
96                spinlock_unlock(&target_th->lock);
97                spinlock_unlock_nosched(&task->th_lock);
98                sched_sleep(this);
99                retval = this->info.exit_value;
100        }
101        else
102        {
103                retval = target_th->info.exit_value;
104                wakeup_one(&target_th->info.wait_queue, WAIT_ANY);
105                spinlock_unlock(&target_th->lock);
106                spinlock_unlock(&task->th_lock);
107        }
108
109        /* Probably will not fail */
110        if(thread_return)
111        {
112                if((err = cpu_copy_to_uspace(thread_return, &retval, sizeof(void *)))) 
113                        goto fail_uspace;
114        }
115
116        return 0;
117
118fail_joined:
119fail_joinable:
120fail_deadlock:
121fail_srch:
122        spinlock_unlock(&task->th_lock); 
123
124fail_uspace:
125fail_uspace_ret:
126fail_arg:
127        this->info.errno = err;
128        return err;
129}
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