WebSVN – HelenOS – Diff – /branches/dynload/kernel/generic/src/synch/futex.c


/*
 * Copyright (c) 2006 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
/** @addtogroup sync
 * @{
 */
 
/**
 * @file
 * @brief   Kernel backend for futexes.
 */
 
#include <synch/futex.h>
#include <synch/rwlock.h>
#include <synch/spinlock.h>
#include <synch/synch.h>
#include <mm/frame.h>
#include <mm/page.h>
#include <mm/slab.h>
#include <proc/thread.h>
#include <proc/task.h>
#include <genarch/mm/page_pt.h>
#include <genarch/mm/page_ht.h>
#include <adt/hash_table.h>
#include <adt/list.h>
#include <arch.h>
#include <align.h>
#include <panic.h>
#include <errno.h>
#include <print.h>
 
#define FUTEX_HT_SIZE   1024    /* keep it a power of 2 */
 
static void futex_initialize(futex_t *futex);
 
static futex_t *futex_find(uintptr_t paddr);
static index_t futex_ht_hash(unative_t *key);
static bool futex_ht_compare(unative_t *key, count_t keys, link_t *item);
static void futex_ht_remove_callback(link_t *item);
 
/**
 * Read-write lock protecting global futex hash table.
 * It is also used to serialize access to all futex_t structures.
 * Must be acquired before the task futex B+tree lock.
 */
static rwlock_t futex_ht_lock;
 
/** Futex hash table. */
static hash_table_t futex_ht;
 
/** Futex hash table operations. */
static hash_table_operations_t futex_ht_ops = {
    .hash = futex_ht_hash,
    .compare = futex_ht_compare,
    .remove_callback = futex_ht_remove_callback
};
 
/** Initialize futex subsystem. */
void futex_init(void)
{
    rwlock_initialize(&futex_ht_lock);
    hash_table_create(&futex_ht, FUTEX_HT_SIZE, 1, &futex_ht_ops);
}
 
/** Initialize kernel futex structure.
 *
 * @param futex Kernel futex structure.
 */
void futex_initialize(futex_t *futex)
{
    waitq_initialize(&futex->wq);
    link_initialize(&futex->ht_link);
    futex->paddr = 0;
    futex->refcount = 1;
}
 
/** Sleep in futex wait queue.
 *
 * @param uaddr Userspace address of the futex counter.
 * @param usec If non-zero, number of microseconds this thread is willing to
 *     sleep.
 * @param flags Select mode of operation.
 *
 * @return One of ESYNCH_TIMEOUT, ESYNCH_OK_ATOMIC and ESYNCH_OK_BLOCKED. See
 *     synch.h. If there is no physical mapping for uaddr ENOENT is returned.
 */
unative_t sys_futex_sleep_timeout(uintptr_t uaddr, uint32_t usec, int flags)
{
    futex_t *futex;
    uintptr_t paddr;
    pte_t *t;
    ipl_t ipl;
    int rc;
   
    ipl = interrupts_disable();
 
    /*
     * Find physical address of futex counter.
     */
    page_table_lock(AS, true);
    t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE));
    if (!t || !PTE_VALID(t) || !PTE_PRESENT(t)) {
        page_table_unlock(AS, true);
        interrupts_restore(ipl);
        return (unative_t) ENOENT;
    }
    paddr = PTE_GET_FRAME(t) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE));
    page_table_unlock(AS, true);
   
    interrupts_restore(ipl);   
 
    futex = futex_find(paddr);
 
#ifdef CONFIG_UDEBUG
    udebug_stoppable_begin();
#endif
    rc = waitq_sleep_timeout(&futex->wq, usec, flags |
        SYNCH_FLAGS_INTERRUPTIBLE);
 
#ifdef CONFIG_UDEBUG
    udebug_stoppable_end();
#endif
    return (unative_t) rc;
}
 
/** Wakeup one thread waiting in futex wait queue.
 *
 * @param uaddr Userspace address of the futex counter.
 *
 * @return ENOENT if there is no physical mapping for uaddr.
 */
unative_t sys_futex_wakeup(uintptr_t uaddr)
{
    futex_t *futex;
    uintptr_t paddr;
    pte_t *t;
    ipl_t ipl;
   
    ipl = interrupts_disable();
   
    /*
     * Find physical address of futex counter.
     */
    page_table_lock(AS, true);
    t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE));
    if (!t || !PTE_VALID(t) || !PTE_PRESENT(t)) {
        page_table_unlock(AS, true);
        interrupts_restore(ipl);
        return (unative_t) ENOENT;
    }
    paddr = PTE_GET_FRAME(t) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE));
    page_table_unlock(AS, true);
   
    interrupts_restore(ipl);
 
    futex = futex_find(paddr);
       
    waitq_wakeup(&futex->wq, WAKEUP_FIRST);
   
    return 0;
}
 
/** Find kernel address of the futex structure corresponding to paddr.
 *
 * If the structure does not exist already, a new one is created.
 *
 * @param paddr Physical address of the userspace futex counter.
 *
 * @return Address of the kernel futex structure.
 */
futex_t *futex_find(uintptr_t paddr)
{
    link_t *item;
    futex_t *futex;
    btree_node_t *leaf;
   
    /*
     * Find the respective futex structure
     * or allocate new one if it does not exist already.
     */
    rwlock_read_lock(&futex_ht_lock);
    item = hash_table_find(&futex_ht, &paddr);
    if (item) {
        futex = hash_table_get_instance(item, futex_t, ht_link);
 
        /*
         * See if the current task knows this futex.
         */
        mutex_lock(&TASK->futexes_lock);
        if (!btree_search(&TASK->futexes, paddr, &leaf)) {
            /*
             * The futex is new to the current task.
             * However, we only have read access.
             * Gain write access and try again.
             */
            mutex_unlock(&TASK->futexes_lock);
            goto gain_write_access;
        }
        mutex_unlock(&TASK->futexes_lock);
 
        rwlock_read_unlock(&futex_ht_lock);
    } else {
gain_write_access:
        /*
         * Upgrade to writer is not currently supported,
         * therefore, it is necessary to release the read lock
         * and reacquire it as a writer.
         */
        rwlock_read_unlock(&futex_ht_lock);
 
        rwlock_write_lock(&futex_ht_lock);
        /*
         * Avoid possible race condition by searching
         * the hash table once again with write access.
         */
        item = hash_table_find(&futex_ht, &paddr);
        if (item) {
            futex = hash_table_get_instance(item, futex_t, ht_link);
           
            /*
             * See if this futex is known to the current task.
             */
            mutex_lock(&TASK->futexes_lock);
            if (!btree_search(&TASK->futexes, paddr, &leaf)) {
                /*
                 * The futex is new to the current task.
                 * Upgrade its reference count and put it to the
                 * current task's B+tree of known futexes.
                 */
                futex->refcount++;
                btree_insert(&TASK->futexes, paddr, futex,
                    leaf);
            }
            mutex_unlock(&TASK->futexes_lock);
   
            rwlock_write_unlock(&futex_ht_lock);
        } else {
            futex = (futex_t *) malloc(sizeof(futex_t), 0);
            futex_initialize(futex);
            futex->paddr = paddr;
            hash_table_insert(&futex_ht, &paddr, &futex->ht_link);
           
            /*
             * This is the first task referencing the futex.
             * It can be directly inserted into its
             * B+tree of known futexes.
             */
            mutex_lock(&TASK->futexes_lock);
            btree_insert(&TASK->futexes, paddr, futex, NULL);
            mutex_unlock(&TASK->futexes_lock);
           
            rwlock_write_unlock(&futex_ht_lock);
        }
    }
   
    return futex;
}
 
/** Compute hash index into futex hash table.
 *
 * @param key Address where the key (i.e. physical address of futex counter) is
 *     stored.
 *
 * @return Index into futex hash table.
 */
index_t futex_ht_hash(unative_t *key)
{
    return *key & (FUTEX_HT_SIZE-1);
}
 
/** Compare futex hash table item with a key.
 *
 * @param key Address where the key (i.e. physical address of futex counter) is
 *     stored.
 *
 * @return True if the item matches the key. False otherwise.
 */
bool futex_ht_compare(unative_t *key, count_t keys, link_t *item)
{
    futex_t *futex;
 
    ASSERT(keys == 1);
 
    futex = hash_table_get_instance(item, futex_t, ht_link);
    return *key == futex->paddr;
}
 
/** Callback for removal items from futex hash table.
 *
 * @param item Item removed from the hash table.
 */
void futex_ht_remove_callback(link_t *item)
{
    futex_t *futex;
 
    futex = hash_table_get_instance(item, futex_t, ht_link);
    free(futex);
}
 
/** Remove references from futexes known to the current task. */
void futex_cleanup(void)
{
    link_t *cur;
   
    rwlock_write_lock(&futex_ht_lock);
    mutex_lock(&TASK->futexes_lock);
 
    for (cur = TASK->futexes.leaf_head.next;
        cur != &TASK->futexes.leaf_head; cur = cur->next) {
        btree_node_t *node;
        unsigned int i;
       
        node = list_get_instance(cur, btree_node_t, leaf_link);
        for (i = 0; i < node->keys; i++) {
            futex_t *ftx;
            uintptr_t paddr = node->key[i];
           
            ftx = (futex_t *) node->value[i];
            if (--ftx->refcount == 0)
                hash_table_remove(&futex_ht, &paddr, 1);
        }
    }
   
    mutex_unlock(&TASK->futexes_lock);
    rwlock_write_unlock(&futex_ht_lock);
}
 
/** @}
 */
 

Rev 2927	Rev 3674
1	/*	1	/*
2	* Copyright (c) 2006 Jakub Jermar	2	* Copyright (c) 2006 Jakub Jermar
3	* All rights reserved.	3	* All rights reserved.
4	*	4	*
5	* Redistribution and use in source and binary forms, with or without	5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions	6	* modification, are permitted provided that the following conditions
7	* are met:	7	* are met:
8	*	8	*
9	* - Redistributions of source code must retain the above copyright	9	* - Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.	10	* notice, this list of conditions and the following disclaimer.
11	* - Redistributions in binary form must reproduce the above copyright	11	* - Redistributions in binary form must reproduce the above copyright
12	* notice, this list of conditions and the following disclaimer in the	12	* notice, this list of conditions and the following disclaimer in the
13	* documentation and/or other materials provided with the distribution.	13	* documentation and/or other materials provided with the distribution.
14	* - The name of the author may not be used to endorse or promote products	14	* - The name of the author may not be used to endorse or promote products
15	* derived from this software without specific prior written permission.	15	* derived from this software without specific prior written permission.
16	*	16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR	17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES	18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.	19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,	20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT	21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,	22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY	23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF	25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27	*/	27	*/
28		28
29	/** @addtogroup sync	29	/** @addtogroup sync
30	* @{	30	* @{
31	*/	31	*/
32		32
33	/**	33	/**
34	* @file	34	* @file
35	* @brief Kernel backend for futexes.	35	* @brief Kernel backend for futexes.
36	*/	36	*/
37		37
38	#include <synch/futex.h>	38	#include <synch/futex.h>
39	#include <synch/rwlock.h>	39	#include <synch/rwlock.h>
40	#include <synch/spinlock.h>	40	#include <synch/spinlock.h>
41	#include <synch/synch.h>	41	#include <synch/synch.h>
42	#include <mm/frame.h>	42	#include <mm/frame.h>
43	#include <mm/page.h>	43	#include <mm/page.h>
44	#include <mm/slab.h>	44	#include <mm/slab.h>
45	#include <proc/thread.h>	45	#include <proc/thread.h>
46	#include <proc/task.h>	46	#include <proc/task.h>
47	#include <genarch/mm/page_pt.h>	47	#include <genarch/mm/page_pt.h>
48	#include <genarch/mm/page_ht.h>	48	#include <genarch/mm/page_ht.h>
49	#include <adt/hash_table.h>	49	#include <adt/hash_table.h>
50	#include <adt/list.h>	50	#include <adt/list.h>
51	#include <arch.h>	51	#include <arch.h>
52	#include <align.h>	52	#include <align.h>
53	#include <panic.h>	53	#include <panic.h>
54	#include <errno.h>	54	#include <errno.h>
55	#include <print.h>	55	#include <print.h>
56		56
57	#define FUTEX_HT_SIZE 1024 /* keep it a power of 2 */	57	#define FUTEX_HT_SIZE 1024 /* keep it a power of 2 */
58		58
59	static void futex_initialize(futex_t *futex);	59	static void futex_initialize(futex_t *futex);
60		60
61	static futex_t *futex_find(uintptr_t paddr);	61	static futex_t *futex_find(uintptr_t paddr);
62	static index_t futex_ht_hash(unative_t *key);	62	static index_t futex_ht_hash(unative_t *key);
63	static bool futex_ht_compare(unative_t key, count_t keys, link_t item);	63	static bool futex_ht_compare(unative_t key, count_t keys, link_t item);
64	static void futex_ht_remove_callback(link_t *item);	64	static void futex_ht_remove_callback(link_t *item);
65		65
66	/**	66	/**
67	* Read-write lock protecting global futex hash table.	67	* Read-write lock protecting global futex hash table.
68	* It is also used to serialize access to all futex_t structures.	68	* It is also used to serialize access to all futex_t structures.
69	* Must be acquired before the task futex B+tree lock.	69	* Must be acquired before the task futex B+tree lock.
70	*/	70	*/
71	static rwlock_t futex_ht_lock;	71	static rwlock_t futex_ht_lock;
72		72
73	/** Futex hash table. */	73	/** Futex hash table. */
74	static hash_table_t futex_ht;	74	static hash_table_t futex_ht;
75		75
76	/** Futex hash table operations. */	76	/** Futex hash table operations. */
77	static hash_table_operations_t futex_ht_ops = {	77	static hash_table_operations_t futex_ht_ops = {
78	.hash = futex_ht_hash,	78	.hash = futex_ht_hash,
79	.compare = futex_ht_compare,	79	.compare = futex_ht_compare,
80	.remove_callback = futex_ht_remove_callback	80	.remove_callback = futex_ht_remove_callback
81	};	81	};
82		82
83	/** Initialize futex subsystem. */	83	/** Initialize futex subsystem. */
84	void futex_init(void)	84	void futex_init(void)
85	{	85	{
86	rwlock_initialize(&futex_ht_lock);	86	rwlock_initialize(&futex_ht_lock);
87	hash_table_create(&futex_ht, FUTEX_HT_SIZE, 1, &futex_ht_ops);	87	hash_table_create(&futex_ht, FUTEX_HT_SIZE, 1, &futex_ht_ops);
88	}	88	}
89		89
90	/** Initialize kernel futex structure.	90	/** Initialize kernel futex structure.
91	*	91	*
92	* @param futex Kernel futex structure.	92	* @param futex Kernel futex structure.
93	*/	93	*/
94	void futex_initialize(futex_t *futex)	94	void futex_initialize(futex_t *futex)
95	{	95	{
96	waitq_initialize(&futex->wq);	96	waitq_initialize(&futex->wq);
97	link_initialize(&futex->ht_link);	97	link_initialize(&futex->ht_link);
98	futex->paddr = 0;	98	futex->paddr = 0;
99	futex->refcount = 1;	99	futex->refcount = 1;
100	}	100	}
101		101
102	/** Sleep in futex wait queue.	102	/** Sleep in futex wait queue.
103	*	103	*
104	* @param uaddr Userspace address of the futex counter.	104	* @param uaddr Userspace address of the futex counter.
105	* @param usec If non-zero, number of microseconds this thread is willing to	105	* @param usec If non-zero, number of microseconds this thread is willing to
106	* sleep.	106	* sleep.
107	* @param flags Select mode of operation.	107	* @param flags Select mode of operation.
108	*	108	*
109	* @return One of ESYNCH_TIMEOUT, ESYNCH_OK_ATOMIC and ESYNCH_OK_BLOCKED. See	109	* @return One of ESYNCH_TIMEOUT, ESYNCH_OK_ATOMIC and ESYNCH_OK_BLOCKED. See
110	* synch.h. If there is no physical mapping for uaddr ENOENT is returned.	110	* synch.h. If there is no physical mapping for uaddr ENOENT is returned.
111	*/	111	*/
112	unative_t sys_futex_sleep_timeout(uintptr_t uaddr, uint32_t usec, int flags)	112	unative_t sys_futex_sleep_timeout(uintptr_t uaddr, uint32_t usec, int flags)
113	{	113	{
114	futex_t *futex;	114	futex_t *futex;
115	uintptr_t paddr;	115	uintptr_t paddr;
116	pte_t *t;	116	pte_t *t;
117	ipl_t ipl;	117	ipl_t ipl;
-		118	int rc;
118		119
119	ipl = interrupts_disable();	120	ipl = interrupts_disable();
120		121
121	/*	122	/*
122	* Find physical address of futex counter.	123	* Find physical address of futex counter.
123	*/	124	*/
124	page_table_lock(AS, true);	125	page_table_lock(AS, true);
125	t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE));	126	t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE));
126	if (!t \|\| !PTE_VALID(t) \|\| !PTE_PRESENT(t)) {	127	if (!t \|\| !PTE_VALID(t) \|\| !PTE_PRESENT(t)) {
127	page_table_unlock(AS, true);	128	page_table_unlock(AS, true);
128	interrupts_restore(ipl);	129	interrupts_restore(ipl);
129	return (unative_t) ENOENT;	130	return (unative_t) ENOENT;
130	}	131	}
131	paddr = PTE_GET_FRAME(t) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE));	132	paddr = PTE_GET_FRAME(t) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE));
132	page_table_unlock(AS, true);	133	page_table_unlock(AS, true);
133		134
134	interrupts_restore(ipl);	135	interrupts_restore(ipl);
135		136
136	futex = futex_find(paddr);	137	futex = futex_find(paddr);
137		138
-		139	#ifdef CONFIG_UDEBUG
-		140	udebug_stoppable_begin();
-		141	#endif
138	return (unative_t) waitq_sleep_timeout(&futex->wq, usec, flags \|	142	rc = waitq_sleep_timeout(&futex->wq, usec, flags \|
139	SYNCH_FLAGS_INTERRUPTIBLE);	143	SYNCH_FLAGS_INTERRUPTIBLE);
-		144
-		145	#ifdef CONFIG_UDEBUG
-		146	udebug_stoppable_end();
-		147	#endif
-		148	return (unative_t) rc;
140	}	149	}
141		150
142	/** Wakeup one thread waiting in futex wait queue.	151	/** Wakeup one thread waiting in futex wait queue.
143	*	152	*
144	* @param uaddr Userspace address of the futex counter.	153	* @param uaddr Userspace address of the futex counter.
145	*	154	*
146	* @return ENOENT if there is no physical mapping for uaddr.	155	* @return ENOENT if there is no physical mapping for uaddr.
147	*/	156	*/
148	unative_t sys_futex_wakeup(uintptr_t uaddr)	157	unative_t sys_futex_wakeup(uintptr_t uaddr)
149	{	158	{
150	futex_t *futex;	159	futex_t *futex;
151	uintptr_t paddr;	160	uintptr_t paddr;
152	pte_t *t;	161	pte_t *t;
153	ipl_t ipl;	162	ipl_t ipl;
154		163
155	ipl = interrupts_disable();	164	ipl = interrupts_disable();
156		165
157	/*	166	/*
158	* Find physical address of futex counter.	167	* Find physical address of futex counter.
159	*/	168	*/
160	page_table_lock(AS, true);	169	page_table_lock(AS, true);
161	t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE));	170	t = page_mapping_find(AS, ALIGN_DOWN(uaddr, PAGE_SIZE));
162	if (!t \|\| !PTE_VALID(t) \|\| !PTE_PRESENT(t)) {	171	if (!t \|\| !PTE_VALID(t) \|\| !PTE_PRESENT(t)) {
163	page_table_unlock(AS, true);	172	page_table_unlock(AS, true);
164	interrupts_restore(ipl);	173	interrupts_restore(ipl);
165	return (unative_t) ENOENT;	174	return (unative_t) ENOENT;
166	}	175	}
167	paddr = PTE_GET_FRAME(t) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE));	176	paddr = PTE_GET_FRAME(t) + (uaddr - ALIGN_DOWN(uaddr, PAGE_SIZE));
168	page_table_unlock(AS, true);	177	page_table_unlock(AS, true);
169		178
170	interrupts_restore(ipl);	179	interrupts_restore(ipl);
171		180
172	futex = futex_find(paddr);	181	futex = futex_find(paddr);
173		182
174	waitq_wakeup(&futex->wq, WAKEUP_FIRST);	183	waitq_wakeup(&futex->wq, WAKEUP_FIRST);
175		184
176	return 0;	185	return 0;
177	}	186	}
178		187
179	/** Find kernel address of the futex structure corresponding to paddr.	188	/** Find kernel address of the futex structure corresponding to paddr.
180	*	189	*
181	* If the structure does not exist already, a new one is created.	190	* If the structure does not exist already, a new one is created.
182	*	191	*
183	* @param paddr Physical address of the userspace futex counter.	192	* @param paddr Physical address of the userspace futex counter.
184	*	193	*
185	* @return Address of the kernel futex structure.	194	* @return Address of the kernel futex structure.
186	*/	195	*/
187	futex_t *futex_find(uintptr_t paddr)	196	futex_t *futex_find(uintptr_t paddr)
188	{	197	{
189	link_t *item;	198	link_t *item;
190	futex_t *futex;	199	futex_t *futex;
191	btree_node_t *leaf;	200	btree_node_t *leaf;
192		201
193	/*	202	/*
194	* Find the respective futex structure	203	* Find the respective futex structure
195	* or allocate new one if it does not exist already.	204	* or allocate new one if it does not exist already.
196	*/	205	*/
197	rwlock_read_lock(&futex_ht_lock);	206	rwlock_read_lock(&futex_ht_lock);
198	item = hash_table_find(&futex_ht, &paddr);	207	item = hash_table_find(&futex_ht, &paddr);
199	if (item) {	208	if (item) {
200	futex = hash_table_get_instance(item, futex_t, ht_link);	209	futex = hash_table_get_instance(item, futex_t, ht_link);
201		210
202	/*	211	/*
203	* See if the current task knows this futex.	212	* See if the current task knows this futex.
204	*/	213	*/
205	mutex_lock(&TASK->futexes_lock);	214	mutex_lock(&TASK->futexes_lock);
206	if (!btree_search(&TASK->futexes, paddr, &leaf)) {	215	if (!btree_search(&TASK->futexes, paddr, &leaf)) {
207	/*	216	/*
208	* The futex is new to the current task.	217	* The futex is new to the current task.
209	* However, we only have read access.	218	* However, we only have read access.
210	* Gain write access and try again.	219	* Gain write access and try again.
211	*/	220	*/
212	mutex_unlock(&TASK->futexes_lock);	221	mutex_unlock(&TASK->futexes_lock);
213	goto gain_write_access;	222	goto gain_write_access;
214	}	223	}
215	mutex_unlock(&TASK->futexes_lock);	224	mutex_unlock(&TASK->futexes_lock);
216		225
217	rwlock_read_unlock(&futex_ht_lock);	226	rwlock_read_unlock(&futex_ht_lock);
218	} else {	227	} else {
219	gain_write_access:	228	gain_write_access:
220	/*	229	/*
221	* Upgrade to writer is not currently supported,	230	* Upgrade to writer is not currently supported,
222	* therefore, it is necessary to release the read lock	231	* therefore, it is necessary to release the read lock
223	* and reacquire it as a writer.	232	* and reacquire it as a writer.
224	*/	233	*/
225	rwlock_read_unlock(&futex_ht_lock);	234	rwlock_read_unlock(&futex_ht_lock);
226		235
227	rwlock_write_lock(&futex_ht_lock);	236	rwlock_write_lock(&futex_ht_lock);
228	/*	237	/*
229	* Avoid possible race condition by searching	238	* Avoid possible race condition by searching
230	* the hash table once again with write access.	239	* the hash table once again with write access.
231	*/	240	*/
232	item = hash_table_find(&futex_ht, &paddr);	241	item = hash_table_find(&futex_ht, &paddr);
233	if (item) {	242	if (item) {
234	futex = hash_table_get_instance(item, futex_t, ht_link);	243	futex = hash_table_get_instance(item, futex_t, ht_link);
235		244
236	/*	245	/*
237	* See if this futex is known to the current task.	246	* See if this futex is known to the current task.
238	*/	247	*/
239	mutex_lock(&TASK->futexes_lock);	248	mutex_lock(&TASK->futexes_lock);
240	if (!btree_search(&TASK->futexes, paddr, &leaf)) {	249	if (!btree_search(&TASK->futexes, paddr, &leaf)) {
241	/*	250	/*
242	* The futex is new to the current task.	251	* The futex is new to the current task.
243	* Upgrade its reference count and put it to the	252	* Upgrade its reference count and put it to the
244	* current task's B+tree of known futexes.	253	* current task's B+tree of known futexes.
245	*/	254	*/
246	futex->refcount++;	255	futex->refcount++;
247	btree_insert(&TASK->futexes, paddr, futex,	256	btree_insert(&TASK->futexes, paddr, futex,
248	leaf);	257	leaf);
249	}	258	}
250	mutex_unlock(&TASK->futexes_lock);	259	mutex_unlock(&TASK->futexes_lock);
251		260
252	rwlock_write_unlock(&futex_ht_lock);	261	rwlock_write_unlock(&futex_ht_lock);
253	} else {	262	} else {
254	futex = (futex_t *) malloc(sizeof(futex_t), 0);	263	futex = (futex_t *) malloc(sizeof(futex_t), 0);
255	futex_initialize(futex);	264	futex_initialize(futex);
256	futex->paddr = paddr;	265	futex->paddr = paddr;
257	hash_table_insert(&futex_ht, &paddr, &futex->ht_link);	266	hash_table_insert(&futex_ht, &paddr, &futex->ht_link);
258		267
259	/*	268	/*
260	* This is the first task referencing the futex.	269	* This is the first task referencing the futex.
261	* It can be directly inserted into its	270	* It can be directly inserted into its
262	* B+tree of known futexes.	271	* B+tree of known futexes.
263	*/	272	*/
264	mutex_lock(&TASK->futexes_lock);	273	mutex_lock(&TASK->futexes_lock);
265	btree_insert(&TASK->futexes, paddr, futex, NULL);	274	btree_insert(&TASK->futexes, paddr, futex, NULL);
266	mutex_unlock(&TASK->futexes_lock);	275	mutex_unlock(&TASK->futexes_lock);
267		276
268	rwlock_write_unlock(&futex_ht_lock);	277	rwlock_write_unlock(&futex_ht_lock);
269	}	278	}
270	}	279	}
271		280
272	return futex;	281	return futex;
273	}	282	}
274		283
275	/** Compute hash index into futex hash table.	284	/** Compute hash index into futex hash table.
276	*	285	*
277	* @param key Address where the key (i.e. physical address of futex counter) is	286	* @param key Address where the key (i.e. physical address of futex counter) is
278	* stored.	287	* stored.
279	*	288	*
280	* @return Index into futex hash table.	289	* @return Index into futex hash table.
281	*/	290	*/
282	index_t futex_ht_hash(unative_t *key)	291	index_t futex_ht_hash(unative_t *key)
283	{	292	{
284	return *key & (FUTEX_HT_SIZE-1);	293	return *key & (FUTEX_HT_SIZE-1);
285	}	294	}
286		295
287	/** Compare futex hash table item with a key.	296	/** Compare futex hash table item with a key.
288	*	297	*
289	* @param key Address where the key (i.e. physical address of futex counter) is	298	* @param key Address where the key (i.e. physical address of futex counter) is
290	* stored.	299	* stored.
291	*	300	*
292	* @return True if the item matches the key. False otherwise.	301	* @return True if the item matches the key. False otherwise.
293	*/	302	*/
294	bool futex_ht_compare(unative_t key, count_t keys, link_t item)	303	bool futex_ht_compare(unative_t key, count_t keys, link_t item)
295	{	304	{
296	futex_t *futex;	305	futex_t *futex;
297		306
298	ASSERT(keys == 1);	307	ASSERT(keys == 1);
299		308
300	futex = hash_table_get_instance(item, futex_t, ht_link);	309	futex = hash_table_get_instance(item, futex_t, ht_link);
301	return *key == futex->paddr;	310	return *key == futex->paddr;
302	}	311	}
303		312
304	/** Callback for removal items from futex hash table.	313	/** Callback for removal items from futex hash table.
305	*	314	*
306	* @param item Item removed from the hash table.	315	* @param item Item removed from the hash table.
307	*/	316	*/
308	void futex_ht_remove_callback(link_t *item)	317	void futex_ht_remove_callback(link_t *item)
309	{	318	{
310	futex_t *futex;	319	futex_t *futex;
311		320
312	futex = hash_table_get_instance(item, futex_t, ht_link);	321	futex = hash_table_get_instance(item, futex_t, ht_link);
313	free(futex);	322	free(futex);
314	}	323	}
315		324
316	/** Remove references from futexes known to the current task. */	325	/** Remove references from futexes known to the current task. */
317	void futex_cleanup(void)	326	void futex_cleanup(void)
318	{	327	{
319	link_t *cur;	328	link_t *cur;
320		329
321	rwlock_write_lock(&futex_ht_lock);	330	rwlock_write_lock(&futex_ht_lock);
322	mutex_lock(&TASK->futexes_lock);	331	mutex_lock(&TASK->futexes_lock);
323		332
324	for (cur = TASK->futexes.leaf_head.next;	333	for (cur = TASK->futexes.leaf_head.next;
325	cur != &TASK->futexes.leaf_head; cur = cur->next) {	334	cur != &TASK->futexes.leaf_head; cur = cur->next) {
326	btree_node_t *node;	335	btree_node_t *node;
327	unsigned int i;	336	unsigned int i;
328		337
329	node = list_get_instance(cur, btree_node_t, leaf_link);	338	node = list_get_instance(cur, btree_node_t, leaf_link);
330	for (i = 0; i < node->keys; i++) {	339	for (i = 0; i < node->keys; i++) {
331	futex_t *ftx;	340	futex_t *ftx;
332	uintptr_t paddr = node->key[i];	341	uintptr_t paddr = node->key[i];
333		342
334	ftx = (futex_t *) node->value[i];	343	ftx = (futex_t *) node->value[i];
335	if (--ftx->refcount == 0)	344	if (--ftx->refcount == 0)
336	hash_table_remove(&futex_ht, &paddr, 1);	345	hash_table_remove(&futex_ht, &paddr, 1);
337	}	346	}
338	}	347	}
339		348
340	mutex_unlock(&TASK->futexes_lock);	349	mutex_unlock(&TASK->futexes_lock);
341	rwlock_write_unlock(&futex_ht_lock);	350	rwlock_write_unlock(&futex_ht_lock);
342	}	351	}
343		352
344	/** @}	353	/** @}
345	*/	354	*/
346		355

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(root)/branches/dynload/kernel/generic/src/synch/futex.c – Rev 2927 → 3674