1 include/linux/dynlocks.h | 33 ++++++++++
3 lib/dynlocks.c | 152 +++++++++++++++++++++++++++++++++++++++++++++++
4 3 files changed, 187 insertions(+), 2 deletions(-)
6 Index: linux-2.6.10/fs/dcache.c
7 ===================================================================
8 --- linux-2.6.10.orig/fs/dcache.c 2006-10-21 11:52:54.000000000 +0800
9 +++ linux-2.6.10/fs/dcache.c 2006-10-21 13:04:55.000000000 +0800
12 extern void bdev_cache_init(void);
13 extern void chrdev_init(void);
14 +extern void dynlock_cache_init(void);
16 void __init vfs_caches_init_early(void)
22 + dynlock_cache_init();
25 EXPORT_SYMBOL(d_alloc);
26 Index: linux-2.6.10/include/linux/dynlocks.h
27 ===================================================================
28 --- linux-2.6.10.orig/include/linux/dynlocks.h 2006-05-31 09:15:07.000000000 +0800
29 +++ linux-2.6.10/include/linux/dynlocks.h 2006-10-21 13:04:55.000000000 +0800
31 +#ifndef _LINUX_DYNLOCKS_H
32 +#define _LINUX_DYNLOCKS_H
34 +#include <linux/list.h>
35 +#include <linux/wait.h>
37 +#define DYNLOCK_MAGIC 0xd19a10c
38 +#define DYNLOCK_MAGIC2 0xd1956ee
41 +struct dynlock_handle;
46 + * - lock to protect this list
51 + struct list_head dl_list;
52 + spinlock_t dl_list_lock;
61 +void dynlock_init(struct dynlock *dl);
62 +struct dynlock_handle *dynlock_lock(struct dynlock *dl, unsigned long value,
63 + enum dynlock_type lt, int gfp);
64 +void dynlock_unlock(struct dynlock *dl, struct dynlock_handle *lock);
68 Index: linux-2.6.10/lib/Makefile
69 ===================================================================
70 --- linux-2.6.10.orig/lib/Makefile 2004-12-25 05:33:50.000000000 +0800
71 +++ linux-2.6.10/lib/Makefile 2006-10-21 13:08:20.000000000 +0800
73 lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \
74 bust_spinlocks.o rbtree.o radix-tree.o dump_stack.o \
75 kobject.o kref.o idr.o div64.o parser.o int_sqrt.o \
76 - bitmap.o extable.o kobject_uevent.o
77 + bitmap.o extable.o kobject_uevent.o dynlocks.o
79 ifeq ($(CONFIG_DEBUG_KOBJECT),y)
80 CFLAGS_kobject.o += -DDEBUG
81 Index: linux-2.6.10/lib/dynlocks.c
82 ===================================================================
83 --- linux-2.6.10.orig/lib/dynlocks.c 2006-05-31 09:15:07.000000000 +0800
84 +++ linux-2.6.10/lib/dynlocks.c 2006-10-21 13:04:55.000000000 +0800
89 + * struct dynlock is lockspace
90 + * one may request lock (exclusive or shared) for some value
95 +#include <linux/dynlocks.h>
96 +#include <linux/module.h>
97 +#include <linux/slab.h>
98 +#include <linux/sched.h>
100 +static kmem_cache_t * dynlock_cachep = NULL;
102 +struct dynlock_handle {
104 + struct list_head dl_list;
105 + unsigned long dl_value; /* lock value */
106 + int dl_refcount; /* number of users */
109 + int dl_pid; /* holder of the lock */
110 + wait_queue_head_t dl_wait;
113 +#define DYNLOCK_LIST_MAGIC 0x11ee91e6
115 +void __init dynlock_cache_init(void)
117 + printk(KERN_INFO "init dynlocks cache\n");
118 + dynlock_cachep = kmem_cache_create("dynlock_cache",
119 + sizeof(struct dynlock_handle),
121 + SLAB_HWCACHE_ALIGN,
123 + if (dynlock_cachep == NULL)
124 + panic("Can't create dynlock cache");
130 + * initialize lockspace
133 +void dynlock_init(struct dynlock *dl)
135 + spin_lock_init(&dl->dl_list_lock);
136 + INIT_LIST_HEAD(&dl->dl_list);
137 + dl->dl_magic = DYNLOCK_LIST_MAGIC;
143 + * acquires lock (exclusive or shared) in specified lockspace
144 + * each lock in lockspace is allocated separately, so user have
145 + * to specify GFP flags.
146 + * routine returns pointer to lock. this pointer is intended to
147 + * be passed to dynlock_unlock
150 +struct dynlock_handle *dynlock_lock(struct dynlock *dl, unsigned long value,
151 + enum dynlock_type lt, int gfp)
153 + struct dynlock_handle *nhl = NULL;
154 + struct dynlock_handle *hl;
155 + struct list_head *cur;
158 + BUG_ON(dl == NULL);
159 + BUG_ON(dl->dl_magic != DYNLOCK_LIST_MAGIC);
161 + if (lt == DLT_NONE)
164 + /* find requested lock in lockspace */
165 + spin_lock(&dl->dl_list_lock);
166 + BUG_ON(dl->dl_list.next == NULL);
167 + BUG_ON(dl->dl_list.prev == NULL);
168 + list_for_each(cur, &dl->dl_list) {
169 + BUG_ON(cur->next == NULL);
170 + BUG_ON(cur->prev == NULL);
171 + hl = list_entry(cur, struct dynlock_handle, dl_list);
172 + BUG_ON(hl->dl_magic != DYNLOCK_MAGIC);
173 + if (hl->dl_value == value) {
174 + /* lock is found */
176 + /* someone else just allocated
177 + * lock we didn't find and just created
178 + * so, we drop our lock
180 + kmem_cache_free(dynlock_cachep, nhl);
188 + /* lock not found */
190 + /* we already have allocated lock. use it */
193 + list_add(&hl->dl_list, &dl->dl_list);
196 + spin_unlock(&dl->dl_list_lock);
198 + /* lock not found and we haven't allocated lock yet. allocate it */
199 + nhl = kmem_cache_alloc(dynlock_cachep, gfp);
202 + nhl->dl_refcount = 1;
203 + nhl->dl_value = value;
204 + nhl->dl_readers = 0;
205 + nhl->dl_writers = 0;
206 + nhl->dl_magic = DYNLOCK_MAGIC;
207 + init_waitqueue_head(&nhl->dl_wait);
209 + /* while lock is being allocated, someone else may allocate it
210 + * and put onto to list. check this situation
215 + if (lt == DLT_WRITE) {
216 + /* exclusive lock: user don't want to share lock at all
217 + * NOTE: one process may take the same lock several times
218 + * this functionaly is useful for rename operations */
219 + while ((hl->dl_writers && hl->dl_pid != current->pid) ||
221 + spin_unlock(&dl->dl_list_lock);
222 + wait_event(hl->dl_wait,
223 + hl->dl_writers == 0 && hl->dl_readers == 0);
224 + spin_lock(&dl->dl_list_lock);
228 + /* shared lock: user do not want to share lock with writer */
229 + while (hl->dl_writers) {
230 + spin_unlock(&dl->dl_list_lock);
231 + wait_event(hl->dl_wait, hl->dl_writers == 0);
232 + spin_lock(&dl->dl_list_lock);
236 + hl->dl_pid = current->pid;
237 + spin_unlock(&dl->dl_list_lock);
246 + * user have to specify lockspace (dl) and pointer to lock structure
247 + * returned by dynlock_lock()
250 +void dynlock_unlock(struct dynlock *dl, struct dynlock_handle *hl)
254 + BUG_ON(dl == NULL);
255 + BUG_ON(hl == NULL);
256 + BUG_ON(dl->dl_magic != DYNLOCK_LIST_MAGIC);
257 + BUG_ON(hl->dl_magic != DYNLOCK_MAGIC);
258 + BUG_ON(current->pid != hl->dl_pid);
260 + spin_lock(&dl->dl_list_lock);
261 + if (hl->dl_writers) {
262 + BUG_ON(hl->dl_readers > 0 || hl->dl_readers < 0);
264 + if (hl->dl_writers == 0)
266 + } else if (hl->dl_readers) {
268 + if (hl->dl_readers == 0)
275 + wake_up(&hl->dl_wait);
277 + if (--(hl->dl_refcount) == 0) {
278 + hl->dl_magic = DYNLOCK_MAGIC2;
279 + list_del(&hl->dl_list);
280 + kmem_cache_free(dynlock_cachep, hl);
282 + spin_unlock(&dl->dl_list_lock);
285 +EXPORT_SYMBOL(dynlock_init);
286 +EXPORT_SYMBOL(dynlock_lock);
287 +EXPORT_SYMBOL(dynlock_unlock);