Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * fs/eventpoll.c ( Efficent event polling implementation ) | |
3419b23a | 3 | * Copyright (C) 2001,...,2006 Davide Libenzi |
1da177e4 LT |
4 | * |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation; either version 2 of the License, or | |
8 | * (at your option) any later version. | |
9 | * | |
10 | * Davide Libenzi <davidel@xmailserver.org> | |
11 | * | |
12 | */ | |
13 | ||
14 | #include <linux/module.h> | |
15 | #include <linux/init.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/sched.h> | |
18 | #include <linux/fs.h> | |
19 | #include <linux/file.h> | |
20 | #include <linux/signal.h> | |
21 | #include <linux/errno.h> | |
22 | #include <linux/mm.h> | |
23 | #include <linux/slab.h> | |
24 | #include <linux/poll.h> | |
1da177e4 LT |
25 | #include <linux/string.h> |
26 | #include <linux/list.h> | |
27 | #include <linux/hash.h> | |
28 | #include <linux/spinlock.h> | |
29 | #include <linux/syscalls.h> | |
30 | #include <linux/rwsem.h> | |
31 | #include <linux/rbtree.h> | |
32 | #include <linux/wait.h> | |
33 | #include <linux/eventpoll.h> | |
34 | #include <linux/mount.h> | |
35 | #include <linux/bitops.h> | |
144efe3e | 36 | #include <linux/mutex.h> |
1da177e4 LT |
37 | #include <asm/uaccess.h> |
38 | #include <asm/system.h> | |
39 | #include <asm/io.h> | |
40 | #include <asm/mman.h> | |
41 | #include <asm/atomic.h> | |
42 | #include <asm/semaphore.h> | |
43 | ||
44 | ||
45 | /* | |
46 | * LOCKING: | |
47 | * There are three level of locking required by epoll : | |
48 | * | |
144efe3e | 49 | * 1) epmutex (mutex) |
1da177e4 LT |
50 | * 2) ep->sem (rw_semaphore) |
51 | * 3) ep->lock (rw_lock) | |
52 | * | |
53 | * The acquire order is the one listed above, from 1 to 3. | |
54 | * We need a spinlock (ep->lock) because we manipulate objects | |
55 | * from inside the poll callback, that might be triggered from | |
56 | * a wake_up() that in turn might be called from IRQ context. | |
57 | * So we can't sleep inside the poll callback and hence we need | |
58 | * a spinlock. During the event transfer loop (from kernel to | |
59 | * user space) we could end up sleeping due a copy_to_user(), so | |
60 | * we need a lock that will allow us to sleep. This lock is a | |
61 | * read-write semaphore (ep->sem). It is acquired on read during | |
62 | * the event transfer loop and in write during epoll_ctl(EPOLL_CTL_DEL) | |
63 | * and during eventpoll_release_file(). Then we also need a global | |
64 | * semaphore to serialize eventpoll_release_file() and ep_free(). | |
65 | * This semaphore is acquired by ep_free() during the epoll file | |
66 | * cleanup path and it is also acquired by eventpoll_release_file() | |
67 | * if a file has been pushed inside an epoll set and it is then | |
68 | * close()d without a previous call toepoll_ctl(EPOLL_CTL_DEL). | |
69 | * It is possible to drop the "ep->sem" and to use the global | |
144efe3e | 70 | * semaphore "epmutex" (together with "ep->lock") to have it working, |
1da177e4 | 71 | * but having "ep->sem" will make the interface more scalable. |
144efe3e | 72 | * Events that require holding "epmutex" are very rare, while for |
1da177e4 LT |
73 | * normal operations the epoll private "ep->sem" will guarantee |
74 | * a greater scalability. | |
75 | */ | |
76 | ||
77 | ||
78 | #define EVENTPOLLFS_MAGIC 0x03111965 /* My birthday should work for this :) */ | |
79 | ||
80 | #define DEBUG_EPOLL 0 | |
81 | ||
82 | #if DEBUG_EPOLL > 0 | |
83 | #define DPRINTK(x) printk x | |
84 | #define DNPRINTK(n, x) do { if ((n) <= DEBUG_EPOLL) printk x; } while (0) | |
85 | #else /* #if DEBUG_EPOLL > 0 */ | |
86 | #define DPRINTK(x) (void) 0 | |
87 | #define DNPRINTK(n, x) (void) 0 | |
88 | #endif /* #if DEBUG_EPOLL > 0 */ | |
89 | ||
90 | #define DEBUG_EPI 0 | |
91 | ||
92 | #if DEBUG_EPI != 0 | |
93 | #define EPI_SLAB_DEBUG (SLAB_DEBUG_FREE | SLAB_RED_ZONE /* | SLAB_POISON */) | |
94 | #else /* #if DEBUG_EPI != 0 */ | |
95 | #define EPI_SLAB_DEBUG 0 | |
96 | #endif /* #if DEBUG_EPI != 0 */ | |
97 | ||
98 | /* Epoll private bits inside the event mask */ | |
99 | #define EP_PRIVATE_BITS (EPOLLONESHOT | EPOLLET) | |
100 | ||
101 | /* Maximum number of poll wake up nests we are allowing */ | |
102 | #define EP_MAX_POLLWAKE_NESTS 4 | |
103 | ||
e3306dd5 DL |
104 | /* Maximum msec timeout value storeable in a long int */ |
105 | #define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, (LONG_MAX - 999ULL) / HZ) | |
106 | ||
b611967d DL |
107 | #define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event)) |
108 | ||
e3306dd5 | 109 | |
1da177e4 LT |
110 | struct epoll_filefd { |
111 | struct file *file; | |
112 | int fd; | |
113 | }; | |
114 | ||
115 | /* | |
116 | * Node that is linked into the "wake_task_list" member of the "struct poll_safewake". | |
117 | * It is used to keep track on all tasks that are currently inside the wake_up() code | |
118 | * to 1) short-circuit the one coming from the same task and same wait queue head | |
119 | * ( loop ) 2) allow a maximum number of epoll descriptors inclusion nesting | |
120 | * 3) let go the ones coming from other tasks. | |
121 | */ | |
122 | struct wake_task_node { | |
123 | struct list_head llink; | |
36c8b586 | 124 | struct task_struct *task; |
1da177e4 LT |
125 | wait_queue_head_t *wq; |
126 | }; | |
127 | ||
128 | /* | |
129 | * This is used to implement the safe poll wake up avoiding to reenter | |
130 | * the poll callback from inside wake_up(). | |
131 | */ | |
132 | struct poll_safewake { | |
133 | struct list_head wake_task_list; | |
134 | spinlock_t lock; | |
135 | }; | |
136 | ||
137 | /* | |
138 | * This structure is stored inside the "private_data" member of the file | |
139 | * structure and rapresent the main data sructure for the eventpoll | |
140 | * interface. | |
141 | */ | |
142 | struct eventpoll { | |
143 | /* Protect the this structure access */ | |
144 | rwlock_t lock; | |
145 | ||
146 | /* | |
147 | * This semaphore is used to ensure that files are not removed | |
148 | * while epoll is using them. This is read-held during the event | |
149 | * collection loop and it is write-held during the file cleanup | |
150 | * path, the epoll file exit code and the ctl operations. | |
151 | */ | |
152 | struct rw_semaphore sem; | |
153 | ||
154 | /* Wait queue used by sys_epoll_wait() */ | |
155 | wait_queue_head_t wq; | |
156 | ||
157 | /* Wait queue used by file->poll() */ | |
158 | wait_queue_head_t poll_wait; | |
159 | ||
160 | /* List of ready file descriptors */ | |
161 | struct list_head rdllist; | |
162 | ||
163 | /* RB-Tree root used to store monitored fd structs */ | |
164 | struct rb_root rbr; | |
165 | }; | |
166 | ||
167 | /* Wait structure used by the poll hooks */ | |
168 | struct eppoll_entry { | |
169 | /* List header used to link this structure to the "struct epitem" */ | |
170 | struct list_head llink; | |
171 | ||
172 | /* The "base" pointer is set to the container "struct epitem" */ | |
173 | void *base; | |
174 | ||
175 | /* | |
176 | * Wait queue item that will be linked to the target file wait | |
177 | * queue head. | |
178 | */ | |
179 | wait_queue_t wait; | |
180 | ||
181 | /* The wait queue head that linked the "wait" wait queue item */ | |
182 | wait_queue_head_t *whead; | |
183 | }; | |
184 | ||
185 | /* | |
186 | * Each file descriptor added to the eventpoll interface will | |
6192bd53 | 187 | * have an entry of this type linked to the "rbr" RB tree. |
1da177e4 LT |
188 | */ |
189 | struct epitem { | |
190 | /* RB-Tree node used to link this structure to the eventpoll rb-tree */ | |
191 | struct rb_node rbn; | |
192 | ||
193 | /* List header used to link this structure to the eventpoll ready list */ | |
194 | struct list_head rdllink; | |
195 | ||
196 | /* The file descriptor information this item refers to */ | |
197 | struct epoll_filefd ffd; | |
198 | ||
199 | /* Number of active wait queue attached to poll operations */ | |
200 | int nwait; | |
201 | ||
202 | /* List containing poll wait queues */ | |
203 | struct list_head pwqlist; | |
204 | ||
205 | /* The "container" of this item */ | |
206 | struct eventpoll *ep; | |
207 | ||
208 | /* The structure that describe the interested events and the source fd */ | |
209 | struct epoll_event event; | |
210 | ||
211 | /* | |
212 | * Used to keep track of the usage count of the structure. This avoids | |
213 | * that the structure will desappear from underneath our processing. | |
214 | */ | |
215 | atomic_t usecnt; | |
216 | ||
217 | /* List header used to link this item to the "struct file" items list */ | |
218 | struct list_head fllink; | |
1da177e4 LT |
219 | }; |
220 | ||
221 | /* Wrapper struct used by poll queueing */ | |
222 | struct ep_pqueue { | |
223 | poll_table pt; | |
224 | struct epitem *epi; | |
225 | }; | |
226 | ||
227 | ||
228 | ||
229 | static void ep_poll_safewake_init(struct poll_safewake *psw); | |
230 | static void ep_poll_safewake(struct poll_safewake *psw, wait_queue_head_t *wq); | |
53d2be79 DL |
231 | static int ep_getfd(int *efd, struct inode **einode, struct file **efile, |
232 | struct eventpoll *ep); | |
233 | static int ep_alloc(struct eventpoll **pep); | |
1da177e4 LT |
234 | static void ep_free(struct eventpoll *ep); |
235 | static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd); | |
236 | static void ep_use_epitem(struct epitem *epi); | |
237 | static void ep_release_epitem(struct epitem *epi); | |
238 | static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, | |
239 | poll_table *pt); | |
240 | static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi); | |
241 | static int ep_insert(struct eventpoll *ep, struct epoll_event *event, | |
242 | struct file *tfile, int fd); | |
243 | static int ep_modify(struct eventpoll *ep, struct epitem *epi, | |
244 | struct epoll_event *event); | |
245 | static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi); | |
246 | static int ep_unlink(struct eventpoll *ep, struct epitem *epi); | |
247 | static int ep_remove(struct eventpoll *ep, struct epitem *epi); | |
248 | static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key); | |
249 | static int ep_eventpoll_close(struct inode *inode, struct file *file); | |
250 | static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait); | |
1da177e4 | 251 | static int ep_send_events(struct eventpoll *ep, struct list_head *txlist, |
6192bd53 | 252 | struct epoll_event __user *events, int maxevents); |
1da177e4 LT |
253 | static int ep_events_transfer(struct eventpoll *ep, |
254 | struct epoll_event __user *events, | |
255 | int maxevents); | |
256 | static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, | |
257 | int maxevents, long timeout); | |
258 | static int eventpollfs_delete_dentry(struct dentry *dentry); | |
259 | static struct inode *ep_eventpoll_inode(void); | |
454e2398 DH |
260 | static int eventpollfs_get_sb(struct file_system_type *fs_type, |
261 | int flags, const char *dev_name, | |
262 | void *data, struct vfsmount *mnt); | |
1da177e4 LT |
263 | |
264 | /* | |
265 | * This semaphore is used to serialize ep_free() and eventpoll_release_file(). | |
266 | */ | |
144efe3e | 267 | static struct mutex epmutex; |
1da177e4 LT |
268 | |
269 | /* Safe wake up implementation */ | |
270 | static struct poll_safewake psw; | |
271 | ||
272 | /* Slab cache used to allocate "struct epitem" */ | |
e18b890b | 273 | static struct kmem_cache *epi_cache __read_mostly; |
1da177e4 LT |
274 | |
275 | /* Slab cache used to allocate "struct eppoll_entry" */ | |
e18b890b | 276 | static struct kmem_cache *pwq_cache __read_mostly; |
1da177e4 LT |
277 | |
278 | /* Virtual fs used to allocate inodes for eventpoll files */ | |
fa3536cc | 279 | static struct vfsmount *eventpoll_mnt __read_mostly; |
1da177e4 LT |
280 | |
281 | /* File callbacks that implement the eventpoll file behaviour */ | |
4b6f5d20 | 282 | static const struct file_operations eventpoll_fops = { |
1da177e4 LT |
283 | .release = ep_eventpoll_close, |
284 | .poll = ep_eventpoll_poll | |
285 | }; | |
286 | ||
287 | /* | |
288 | * This is used to register the virtual file system from where | |
289 | * eventpoll inodes are allocated. | |
290 | */ | |
291 | static struct file_system_type eventpoll_fs_type = { | |
292 | .name = "eventpollfs", | |
293 | .get_sb = eventpollfs_get_sb, | |
294 | .kill_sb = kill_anon_super, | |
295 | }; | |
296 | ||
297 | /* Very basic directory entry operations for the eventpoll virtual file system */ | |
298 | static struct dentry_operations eventpollfs_dentry_operations = { | |
299 | .d_delete = eventpollfs_delete_dentry, | |
300 | }; | |
301 | ||
302 | ||
303 | ||
b030a4dd PE |
304 | /* Fast test to see if the file is an evenpoll file */ |
305 | static inline int is_file_epoll(struct file *f) | |
306 | { | |
307 | return f->f_op == &eventpoll_fops; | |
308 | } | |
309 | ||
310 | /* Setup the structure that is used as key for the rb-tree */ | |
311 | static inline void ep_set_ffd(struct epoll_filefd *ffd, | |
312 | struct file *file, int fd) | |
313 | { | |
314 | ffd->file = file; | |
315 | ffd->fd = fd; | |
316 | } | |
317 | ||
318 | /* Compare rb-tree keys */ | |
319 | static inline int ep_cmp_ffd(struct epoll_filefd *p1, | |
320 | struct epoll_filefd *p2) | |
321 | { | |
322 | return (p1->file > p2->file ? +1: | |
323 | (p1->file < p2->file ? -1 : p1->fd - p2->fd)); | |
324 | } | |
325 | ||
326 | /* Special initialization for the rb-tree node to detect linkage */ | |
327 | static inline void ep_rb_initnode(struct rb_node *n) | |
328 | { | |
c569882b | 329 | rb_set_parent(n, n); |
b030a4dd PE |
330 | } |
331 | ||
332 | /* Removes a node from the rb-tree and marks it for a fast is-linked check */ | |
333 | static inline void ep_rb_erase(struct rb_node *n, struct rb_root *r) | |
334 | { | |
335 | rb_erase(n, r); | |
c569882b | 336 | rb_set_parent(n, n); |
b030a4dd PE |
337 | } |
338 | ||
339 | /* Fast check to verify that the item is linked to the main rb-tree */ | |
340 | static inline int ep_rb_linked(struct rb_node *n) | |
341 | { | |
c569882b | 342 | return rb_parent(n) != n; |
b030a4dd PE |
343 | } |
344 | ||
b030a4dd PE |
345 | /* Tells us if the item is currently linked */ |
346 | static inline int ep_is_linked(struct list_head *p) | |
347 | { | |
348 | return !list_empty(p); | |
349 | } | |
350 | ||
351 | /* Get the "struct epitem" from a wait queue pointer */ | |
352 | static inline struct epitem * ep_item_from_wait(wait_queue_t *p) | |
353 | { | |
354 | return container_of(p, struct eppoll_entry, wait)->base; | |
355 | } | |
356 | ||
357 | /* Get the "struct epitem" from an epoll queue wrapper */ | |
358 | static inline struct epitem * ep_item_from_epqueue(poll_table *p) | |
359 | { | |
360 | return container_of(p, struct ep_pqueue, pt)->epi; | |
361 | } | |
362 | ||
363 | /* Tells if the epoll_ctl(2) operation needs an event copy from userspace */ | |
6192bd53 | 364 | static inline int ep_op_has_event(int op) |
b030a4dd PE |
365 | { |
366 | return op != EPOLL_CTL_DEL; | |
367 | } | |
368 | ||
1da177e4 LT |
369 | /* Initialize the poll safe wake up structure */ |
370 | static void ep_poll_safewake_init(struct poll_safewake *psw) | |
371 | { | |
372 | ||
373 | INIT_LIST_HEAD(&psw->wake_task_list); | |
374 | spin_lock_init(&psw->lock); | |
375 | } | |
376 | ||
377 | ||
378 | /* | |
379 | * Perform a safe wake up of the poll wait list. The problem is that | |
380 | * with the new callback'd wake up system, it is possible that the | |
381 | * poll callback is reentered from inside the call to wake_up() done | |
382 | * on the poll wait queue head. The rule is that we cannot reenter the | |
383 | * wake up code from the same task more than EP_MAX_POLLWAKE_NESTS times, | |
384 | * and we cannot reenter the same wait queue head at all. This will | |
385 | * enable to have a hierarchy of epoll file descriptor of no more than | |
386 | * EP_MAX_POLLWAKE_NESTS deep. We need the irq version of the spin lock | |
387 | * because this one gets called by the poll callback, that in turn is called | |
388 | * from inside a wake_up(), that might be called from irq context. | |
389 | */ | |
390 | static void ep_poll_safewake(struct poll_safewake *psw, wait_queue_head_t *wq) | |
391 | { | |
392 | int wake_nests = 0; | |
393 | unsigned long flags; | |
36c8b586 | 394 | struct task_struct *this_task = current; |
1da177e4 LT |
395 | struct list_head *lsthead = &psw->wake_task_list, *lnk; |
396 | struct wake_task_node *tncur; | |
397 | struct wake_task_node tnode; | |
398 | ||
399 | spin_lock_irqsave(&psw->lock, flags); | |
400 | ||
401 | /* Try to see if the current task is already inside this wakeup call */ | |
402 | list_for_each(lnk, lsthead) { | |
403 | tncur = list_entry(lnk, struct wake_task_node, llink); | |
404 | ||
405 | if (tncur->wq == wq || | |
406 | (tncur->task == this_task && ++wake_nests > EP_MAX_POLLWAKE_NESTS)) { | |
407 | /* | |
408 | * Ops ... loop detected or maximum nest level reached. | |
409 | * We abort this wake by breaking the cycle itself. | |
410 | */ | |
411 | spin_unlock_irqrestore(&psw->lock, flags); | |
412 | return; | |
413 | } | |
414 | } | |
415 | ||
416 | /* Add the current task to the list */ | |
417 | tnode.task = this_task; | |
418 | tnode.wq = wq; | |
419 | list_add(&tnode.llink, lsthead); | |
420 | ||
421 | spin_unlock_irqrestore(&psw->lock, flags); | |
422 | ||
423 | /* Do really wake up now */ | |
424 | wake_up(wq); | |
425 | ||
426 | /* Remove the current task from the list */ | |
427 | spin_lock_irqsave(&psw->lock, flags); | |
428 | list_del(&tnode.llink); | |
429 | spin_unlock_irqrestore(&psw->lock, flags); | |
430 | } | |
431 | ||
432 | ||
1da177e4 LT |
433 | /* |
434 | * This is called from eventpoll_release() to unlink files from the eventpoll | |
435 | * interface. We need to have this facility to cleanup correctly files that are | |
436 | * closed without being removed from the eventpoll interface. | |
437 | */ | |
438 | void eventpoll_release_file(struct file *file) | |
439 | { | |
440 | struct list_head *lsthead = &file->f_ep_links; | |
441 | struct eventpoll *ep; | |
442 | struct epitem *epi; | |
443 | ||
444 | /* | |
445 | * We don't want to get "file->f_ep_lock" because it is not | |
446 | * necessary. It is not necessary because we're in the "struct file" | |
447 | * cleanup path, and this means that noone is using this file anymore. | |
448 | * The only hit might come from ep_free() but by holding the semaphore | |
449 | * will correctly serialize the operation. We do need to acquire | |
144efe3e | 450 | * "ep->sem" after "epmutex" because ep_remove() requires it when called |
1da177e4 LT |
451 | * from anywhere but ep_free(). |
452 | */ | |
144efe3e | 453 | mutex_lock(&epmutex); |
1da177e4 LT |
454 | |
455 | while (!list_empty(lsthead)) { | |
456 | epi = list_entry(lsthead->next, struct epitem, fllink); | |
457 | ||
458 | ep = epi->ep; | |
6192bd53 | 459 | list_del_init(&epi->fllink); |
1da177e4 LT |
460 | down_write(&ep->sem); |
461 | ep_remove(ep, epi); | |
462 | up_write(&ep->sem); | |
463 | } | |
464 | ||
144efe3e | 465 | mutex_unlock(&epmutex); |
1da177e4 LT |
466 | } |
467 | ||
468 | ||
469 | /* | |
470 | * It opens an eventpoll file descriptor by suggesting a storage of "size" | |
471 | * file descriptors. The size parameter is just an hint about how to size | |
472 | * data structures. It won't prevent the user to store more than "size" | |
473 | * file descriptors inside the epoll interface. It is the kernel part of | |
474 | * the userspace epoll_create(2). | |
475 | */ | |
476 | asmlinkage long sys_epoll_create(int size) | |
477 | { | |
b611967d | 478 | int error, fd = -1; |
53d2be79 | 479 | struct eventpoll *ep; |
1da177e4 LT |
480 | struct inode *inode; |
481 | struct file *file; | |
482 | ||
483 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d)\n", | |
484 | current, size)); | |
485 | ||
53d2be79 DL |
486 | /* |
487 | * Sanity check on the size parameter, and create the internal data | |
488 | * structure ( "struct eventpoll" ). | |
489 | */ | |
1da177e4 | 490 | error = -EINVAL; |
53d2be79 | 491 | if (size <= 0 || (error = ep_alloc(&ep)) != 0) |
1da177e4 LT |
492 | goto eexit_1; |
493 | ||
494 | /* | |
495 | * Creates all the items needed to setup an eventpoll file. That is, | |
496 | * a file structure, and inode and a free file descriptor. | |
497 | */ | |
53d2be79 | 498 | error = ep_getfd(&fd, &inode, &file, ep); |
1da177e4 LT |
499 | if (error) |
500 | goto eexit_2; | |
501 | ||
1da177e4 LT |
502 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n", |
503 | current, size, fd)); | |
504 | ||
505 | return fd; | |
506 | ||
507 | eexit_2: | |
53d2be79 DL |
508 | ep_free(ep); |
509 | kfree(ep); | |
1da177e4 LT |
510 | eexit_1: |
511 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n", | |
512 | current, size, error)); | |
513 | return error; | |
514 | } | |
515 | ||
516 | ||
517 | /* | |
518 | * The following function implements the controller interface for | |
519 | * the eventpoll file that enables the insertion/removal/change of | |
520 | * file descriptors inside the interest set. It represents | |
521 | * the kernel part of the user space epoll_ctl(2). | |
522 | */ | |
523 | asmlinkage long | |
524 | sys_epoll_ctl(int epfd, int op, int fd, struct epoll_event __user *event) | |
525 | { | |
526 | int error; | |
527 | struct file *file, *tfile; | |
528 | struct eventpoll *ep; | |
529 | struct epitem *epi; | |
530 | struct epoll_event epds; | |
531 | ||
532 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p)\n", | |
533 | current, epfd, op, fd, event)); | |
534 | ||
535 | error = -EFAULT; | |
6192bd53 | 536 | if (ep_op_has_event(op) && |
1da177e4 LT |
537 | copy_from_user(&epds, event, sizeof(struct epoll_event))) |
538 | goto eexit_1; | |
539 | ||
540 | /* Get the "struct file *" for the eventpoll file */ | |
541 | error = -EBADF; | |
542 | file = fget(epfd); | |
543 | if (!file) | |
544 | goto eexit_1; | |
545 | ||
546 | /* Get the "struct file *" for the target file */ | |
547 | tfile = fget(fd); | |
548 | if (!tfile) | |
549 | goto eexit_2; | |
550 | ||
551 | /* The target file descriptor must support poll */ | |
552 | error = -EPERM; | |
553 | if (!tfile->f_op || !tfile->f_op->poll) | |
554 | goto eexit_3; | |
555 | ||
556 | /* | |
557 | * We have to check that the file structure underneath the file descriptor | |
558 | * the user passed to us _is_ an eventpoll file. And also we do not permit | |
559 | * adding an epoll file descriptor inside itself. | |
560 | */ | |
561 | error = -EINVAL; | |
b030a4dd | 562 | if (file == tfile || !is_file_epoll(file)) |
1da177e4 LT |
563 | goto eexit_3; |
564 | ||
565 | /* | |
566 | * At this point it is safe to assume that the "private_data" contains | |
567 | * our own data structure. | |
568 | */ | |
569 | ep = file->private_data; | |
570 | ||
571 | down_write(&ep->sem); | |
572 | ||
6192bd53 | 573 | /* Try to lookup the file inside our RB tree */ |
1da177e4 LT |
574 | epi = ep_find(ep, tfile, fd); |
575 | ||
576 | error = -EINVAL; | |
577 | switch (op) { | |
578 | case EPOLL_CTL_ADD: | |
579 | if (!epi) { | |
2395140e | 580 | epds.events |= POLLERR | POLLHUP; |
1da177e4 LT |
581 | |
582 | error = ep_insert(ep, &epds, tfile, fd); | |
583 | } else | |
584 | error = -EEXIST; | |
585 | break; | |
586 | case EPOLL_CTL_DEL: | |
587 | if (epi) | |
588 | error = ep_remove(ep, epi); | |
589 | else | |
590 | error = -ENOENT; | |
591 | break; | |
592 | case EPOLL_CTL_MOD: | |
593 | if (epi) { | |
2395140e | 594 | epds.events |= POLLERR | POLLHUP; |
1da177e4 LT |
595 | error = ep_modify(ep, epi, &epds); |
596 | } else | |
597 | error = -ENOENT; | |
598 | break; | |
599 | } | |
600 | ||
601 | /* | |
602 | * The function ep_find() increments the usage count of the structure | |
603 | * so, if this is not NULL, we need to release it. | |
604 | */ | |
605 | if (epi) | |
606 | ep_release_epitem(epi); | |
607 | ||
608 | up_write(&ep->sem); | |
609 | ||
610 | eexit_3: | |
611 | fput(tfile); | |
612 | eexit_2: | |
613 | fput(file); | |
614 | eexit_1: | |
615 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p) = %d\n", | |
616 | current, epfd, op, fd, event, error)); | |
617 | ||
618 | return error; | |
619 | } | |
620 | ||
1da177e4 LT |
621 | |
622 | /* | |
623 | * Implement the event wait interface for the eventpoll file. It is the kernel | |
624 | * part of the user space epoll_wait(2). | |
625 | */ | |
626 | asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events, | |
627 | int maxevents, int timeout) | |
628 | { | |
629 | int error; | |
630 | struct file *file; | |
631 | struct eventpoll *ep; | |
632 | ||
633 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d)\n", | |
634 | current, epfd, events, maxevents, timeout)); | |
635 | ||
636 | /* The maximum number of event must be greater than zero */ | |
b611967d | 637 | if (maxevents <= 0 || maxevents > EP_MAX_EVENTS) |
1da177e4 LT |
638 | return -EINVAL; |
639 | ||
640 | /* Verify that the area passed by the user is writeable */ | |
641 | if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event))) { | |
642 | error = -EFAULT; | |
643 | goto eexit_1; | |
644 | } | |
645 | ||
646 | /* Get the "struct file *" for the eventpoll file */ | |
647 | error = -EBADF; | |
648 | file = fget(epfd); | |
649 | if (!file) | |
650 | goto eexit_1; | |
651 | ||
652 | /* | |
653 | * We have to check that the file structure underneath the fd | |
654 | * the user passed to us _is_ an eventpoll file. | |
655 | */ | |
656 | error = -EINVAL; | |
b030a4dd | 657 | if (!is_file_epoll(file)) |
1da177e4 LT |
658 | goto eexit_2; |
659 | ||
660 | /* | |
661 | * At this point it is safe to assume that the "private_data" contains | |
662 | * our own data structure. | |
663 | */ | |
664 | ep = file->private_data; | |
665 | ||
666 | /* Time to fish for events ... */ | |
667 | error = ep_poll(ep, events, maxevents, timeout); | |
668 | ||
669 | eexit_2: | |
670 | fput(file); | |
671 | eexit_1: | |
672 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d) = %d\n", | |
673 | current, epfd, events, maxevents, timeout, error)); | |
674 | ||
675 | return error; | |
676 | } | |
677 | ||
678 | ||
b611967d DL |
679 | #ifdef TIF_RESTORE_SIGMASK |
680 | ||
681 | /* | |
682 | * Implement the event wait interface for the eventpoll file. It is the kernel | |
683 | * part of the user space epoll_pwait(2). | |
684 | */ | |
685 | asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events, | |
686 | int maxevents, int timeout, const sigset_t __user *sigmask, | |
687 | size_t sigsetsize) | |
688 | { | |
689 | int error; | |
690 | sigset_t ksigmask, sigsaved; | |
691 | ||
692 | /* | |
693 | * If the caller wants a certain signal mask to be set during the wait, | |
694 | * we apply it here. | |
695 | */ | |
696 | if (sigmask) { | |
697 | if (sigsetsize != sizeof(sigset_t)) | |
698 | return -EINVAL; | |
699 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) | |
700 | return -EFAULT; | |
701 | sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP)); | |
702 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
703 | } | |
704 | ||
705 | error = sys_epoll_wait(epfd, events, maxevents, timeout); | |
706 | ||
707 | /* | |
708 | * If we changed the signal mask, we need to restore the original one. | |
709 | * In case we've got a signal while waiting, we do not restore the | |
710 | * signal mask yet, and we allow do_signal() to deliver the signal on | |
711 | * the way back to userspace, before the signal mask is restored. | |
712 | */ | |
713 | if (sigmask) { | |
714 | if (error == -EINTR) { | |
715 | memcpy(¤t->saved_sigmask, &sigsaved, | |
716 | sizeof(sigsaved)); | |
717 | set_thread_flag(TIF_RESTORE_SIGMASK); | |
718 | } else | |
719 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
720 | } | |
721 | ||
722 | return error; | |
723 | } | |
724 | ||
725 | #endif /* #ifdef TIF_RESTORE_SIGMASK */ | |
726 | ||
727 | ||
1da177e4 LT |
728 | /* |
729 | * Creates the file descriptor to be used by the epoll interface. | |
730 | */ | |
53d2be79 DL |
731 | static int ep_getfd(int *efd, struct inode **einode, struct file **efile, |
732 | struct eventpoll *ep) | |
1da177e4 LT |
733 | { |
734 | struct qstr this; | |
735 | char name[32]; | |
736 | struct dentry *dentry; | |
737 | struct inode *inode; | |
738 | struct file *file; | |
739 | int error, fd; | |
740 | ||
741 | /* Get an ready to use file */ | |
742 | error = -ENFILE; | |
743 | file = get_empty_filp(); | |
744 | if (!file) | |
745 | goto eexit_1; | |
746 | ||
747 | /* Allocates an inode from the eventpoll file system */ | |
748 | inode = ep_eventpoll_inode(); | |
c3b65713 JG |
749 | if (IS_ERR(inode)) { |
750 | error = PTR_ERR(inode); | |
1da177e4 | 751 | goto eexit_2; |
c3b65713 | 752 | } |
1da177e4 LT |
753 | |
754 | /* Allocates a free descriptor to plug the file onto */ | |
755 | error = get_unused_fd(); | |
756 | if (error < 0) | |
757 | goto eexit_3; | |
758 | fd = error; | |
759 | ||
760 | /* | |
761 | * Link the inode to a directory entry by creating a unique name | |
762 | * using the inode number. | |
763 | */ | |
764 | error = -ENOMEM; | |
765 | sprintf(name, "[%lu]", inode->i_ino); | |
766 | this.name = name; | |
767 | this.len = strlen(name); | |
768 | this.hash = inode->i_ino; | |
769 | dentry = d_alloc(eventpoll_mnt->mnt_sb->s_root, &this); | |
770 | if (!dentry) | |
771 | goto eexit_4; | |
772 | dentry->d_op = &eventpollfs_dentry_operations; | |
773 | d_add(dentry, inode); | |
0f7fc9e4 JJS |
774 | file->f_path.mnt = mntget(eventpoll_mnt); |
775 | file->f_path.dentry = dentry; | |
1da177e4 LT |
776 | file->f_mapping = inode->i_mapping; |
777 | ||
778 | file->f_pos = 0; | |
779 | file->f_flags = O_RDONLY; | |
780 | file->f_op = &eventpoll_fops; | |
781 | file->f_mode = FMODE_READ; | |
782 | file->f_version = 0; | |
53d2be79 | 783 | file->private_data = ep; |
1da177e4 LT |
784 | |
785 | /* Install the new setup file into the allocated fd. */ | |
786 | fd_install(fd, file); | |
787 | ||
788 | *efd = fd; | |
789 | *einode = inode; | |
790 | *efile = file; | |
791 | return 0; | |
792 | ||
793 | eexit_4: | |
794 | put_unused_fd(fd); | |
795 | eexit_3: | |
796 | iput(inode); | |
797 | eexit_2: | |
798 | put_filp(file); | |
799 | eexit_1: | |
800 | return error; | |
801 | } | |
802 | ||
803 | ||
53d2be79 | 804 | static int ep_alloc(struct eventpoll **pep) |
1da177e4 | 805 | { |
53d2be79 | 806 | struct eventpoll *ep = kzalloc(sizeof(*ep), GFP_KERNEL); |
1da177e4 | 807 | |
53d2be79 | 808 | if (!ep) |
1da177e4 LT |
809 | return -ENOMEM; |
810 | ||
1da177e4 LT |
811 | rwlock_init(&ep->lock); |
812 | init_rwsem(&ep->sem); | |
813 | init_waitqueue_head(&ep->wq); | |
814 | init_waitqueue_head(&ep->poll_wait); | |
815 | INIT_LIST_HEAD(&ep->rdllist); | |
816 | ep->rbr = RB_ROOT; | |
817 | ||
53d2be79 | 818 | *pep = ep; |
1da177e4 | 819 | |
53d2be79 | 820 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_alloc() ep=%p\n", |
1da177e4 LT |
821 | current, ep)); |
822 | return 0; | |
823 | } | |
824 | ||
825 | ||
826 | static void ep_free(struct eventpoll *ep) | |
827 | { | |
828 | struct rb_node *rbp; | |
829 | struct epitem *epi; | |
830 | ||
831 | /* We need to release all tasks waiting for these file */ | |
832 | if (waitqueue_active(&ep->poll_wait)) | |
833 | ep_poll_safewake(&psw, &ep->poll_wait); | |
834 | ||
835 | /* | |
836 | * We need to lock this because we could be hit by | |
837 | * eventpoll_release_file() while we're freeing the "struct eventpoll". | |
838 | * We do not need to hold "ep->sem" here because the epoll file | |
839 | * is on the way to be removed and no one has references to it | |
840 | * anymore. The only hit might come from eventpoll_release_file() but | |
144efe3e | 841 | * holding "epmutex" is sufficent here. |
1da177e4 | 842 | */ |
144efe3e | 843 | mutex_lock(&epmutex); |
1da177e4 LT |
844 | |
845 | /* | |
846 | * Walks through the whole tree by unregistering poll callbacks. | |
847 | */ | |
848 | for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) { | |
849 | epi = rb_entry(rbp, struct epitem, rbn); | |
850 | ||
851 | ep_unregister_pollwait(ep, epi); | |
852 | } | |
853 | ||
854 | /* | |
6192bd53 | 855 | * Walks through the whole tree by freeing each "struct epitem". At this |
1da177e4 LT |
856 | * point we are sure no poll callbacks will be lingering around, and also by |
857 | * write-holding "sem" we can be sure that no file cleanup code will hit | |
858 | * us during this operation. So we can avoid the lock on "ep->lock". | |
859 | */ | |
860 | while ((rbp = rb_first(&ep->rbr)) != 0) { | |
861 | epi = rb_entry(rbp, struct epitem, rbn); | |
862 | ep_remove(ep, epi); | |
863 | } | |
864 | ||
144efe3e | 865 | mutex_unlock(&epmutex); |
1da177e4 LT |
866 | } |
867 | ||
868 | ||
869 | /* | |
6192bd53 | 870 | * Search the file inside the eventpoll tree. It add usage count to |
1da177e4 LT |
871 | * the returned item, so the caller must call ep_release_epitem() |
872 | * after finished using the "struct epitem". | |
873 | */ | |
874 | static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) | |
875 | { | |
876 | int kcmp; | |
877 | unsigned long flags; | |
878 | struct rb_node *rbp; | |
879 | struct epitem *epi, *epir = NULL; | |
880 | struct epoll_filefd ffd; | |
881 | ||
b030a4dd | 882 | ep_set_ffd(&ffd, file, fd); |
1da177e4 LT |
883 | read_lock_irqsave(&ep->lock, flags); |
884 | for (rbp = ep->rbr.rb_node; rbp; ) { | |
885 | epi = rb_entry(rbp, struct epitem, rbn); | |
b030a4dd | 886 | kcmp = ep_cmp_ffd(&ffd, &epi->ffd); |
1da177e4 LT |
887 | if (kcmp > 0) |
888 | rbp = rbp->rb_right; | |
889 | else if (kcmp < 0) | |
890 | rbp = rbp->rb_left; | |
891 | else { | |
892 | ep_use_epitem(epi); | |
893 | epir = epi; | |
894 | break; | |
895 | } | |
896 | } | |
897 | read_unlock_irqrestore(&ep->lock, flags); | |
898 | ||
899 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_find(%p) -> %p\n", | |
900 | current, file, epir)); | |
901 | ||
902 | return epir; | |
903 | } | |
904 | ||
905 | ||
906 | /* | |
907 | * Increment the usage count of the "struct epitem" making it sure | |
908 | * that the user will have a valid pointer to reference. | |
909 | */ | |
910 | static void ep_use_epitem(struct epitem *epi) | |
911 | { | |
912 | ||
913 | atomic_inc(&epi->usecnt); | |
914 | } | |
915 | ||
916 | ||
917 | /* | |
918 | * Decrement ( release ) the usage count by signaling that the user | |
919 | * has finished using the structure. It might lead to freeing the | |
920 | * structure itself if the count goes to zero. | |
921 | */ | |
922 | static void ep_release_epitem(struct epitem *epi) | |
923 | { | |
924 | ||
925 | if (atomic_dec_and_test(&epi->usecnt)) | |
b030a4dd | 926 | kmem_cache_free(epi_cache, epi); |
1da177e4 LT |
927 | } |
928 | ||
929 | ||
930 | /* | |
931 | * This is the callback that is used to add our wait queue to the | |
932 | * target file wakeup lists. | |
933 | */ | |
934 | static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, | |
935 | poll_table *pt) | |
936 | { | |
b030a4dd | 937 | struct epitem *epi = ep_item_from_epqueue(pt); |
1da177e4 LT |
938 | struct eppoll_entry *pwq; |
939 | ||
e94b1766 | 940 | if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) { |
1da177e4 LT |
941 | init_waitqueue_func_entry(&pwq->wait, ep_poll_callback); |
942 | pwq->whead = whead; | |
943 | pwq->base = epi; | |
944 | add_wait_queue(whead, &pwq->wait); | |
945 | list_add_tail(&pwq->llink, &epi->pwqlist); | |
946 | epi->nwait++; | |
947 | } else { | |
948 | /* We have to signal that an error occurred */ | |
949 | epi->nwait = -1; | |
950 | } | |
951 | } | |
952 | ||
953 | ||
954 | static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi) | |
955 | { | |
956 | int kcmp; | |
957 | struct rb_node **p = &ep->rbr.rb_node, *parent = NULL; | |
958 | struct epitem *epic; | |
959 | ||
960 | while (*p) { | |
961 | parent = *p; | |
962 | epic = rb_entry(parent, struct epitem, rbn); | |
b030a4dd | 963 | kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd); |
1da177e4 LT |
964 | if (kcmp > 0) |
965 | p = &parent->rb_right; | |
966 | else | |
967 | p = &parent->rb_left; | |
968 | } | |
969 | rb_link_node(&epi->rbn, parent, p); | |
970 | rb_insert_color(&epi->rbn, &ep->rbr); | |
971 | } | |
972 | ||
973 | ||
974 | static int ep_insert(struct eventpoll *ep, struct epoll_event *event, | |
975 | struct file *tfile, int fd) | |
976 | { | |
977 | int error, revents, pwake = 0; | |
978 | unsigned long flags; | |
979 | struct epitem *epi; | |
980 | struct ep_pqueue epq; | |
981 | ||
982 | error = -ENOMEM; | |
e94b1766 | 983 | if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL))) |
1da177e4 LT |
984 | goto eexit_1; |
985 | ||
986 | /* Item initialization follow here ... */ | |
b030a4dd | 987 | ep_rb_initnode(&epi->rbn); |
1da177e4 LT |
988 | INIT_LIST_HEAD(&epi->rdllink); |
989 | INIT_LIST_HEAD(&epi->fllink); | |
1da177e4 LT |
990 | INIT_LIST_HEAD(&epi->pwqlist); |
991 | epi->ep = ep; | |
b030a4dd | 992 | ep_set_ffd(&epi->ffd, tfile, fd); |
1da177e4 LT |
993 | epi->event = *event; |
994 | atomic_set(&epi->usecnt, 1); | |
995 | epi->nwait = 0; | |
996 | ||
997 | /* Initialize the poll table using the queue callback */ | |
998 | epq.epi = epi; | |
999 | init_poll_funcptr(&epq.pt, ep_ptable_queue_proc); | |
1000 | ||
1001 | /* | |
1002 | * Attach the item to the poll hooks and get current event bits. | |
1003 | * We can safely use the file* here because its usage count has | |
1004 | * been increased by the caller of this function. | |
1005 | */ | |
1006 | revents = tfile->f_op->poll(tfile, &epq.pt); | |
1007 | ||
1008 | /* | |
1009 | * We have to check if something went wrong during the poll wait queue | |
1010 | * install process. Namely an allocation for a wait queue failed due | |
1011 | * high memory pressure. | |
1012 | */ | |
1013 | if (epi->nwait < 0) | |
1014 | goto eexit_2; | |
1015 | ||
1016 | /* Add the current item to the list of active epoll hook for this file */ | |
1017 | spin_lock(&tfile->f_ep_lock); | |
1018 | list_add_tail(&epi->fllink, &tfile->f_ep_links); | |
1019 | spin_unlock(&tfile->f_ep_lock); | |
1020 | ||
1021 | /* We have to drop the new item inside our item list to keep track of it */ | |
1022 | write_lock_irqsave(&ep->lock, flags); | |
1023 | ||
1024 | /* Add the current item to the rb-tree */ | |
1025 | ep_rbtree_insert(ep, epi); | |
1026 | ||
1027 | /* If the file is already "ready" we drop it inside the ready list */ | |
b030a4dd | 1028 | if ((revents & event->events) && !ep_is_linked(&epi->rdllink)) { |
1da177e4 LT |
1029 | list_add_tail(&epi->rdllink, &ep->rdllist); |
1030 | ||
1031 | /* Notify waiting tasks that events are available */ | |
1032 | if (waitqueue_active(&ep->wq)) | |
3419b23a | 1033 | __wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE); |
1da177e4 LT |
1034 | if (waitqueue_active(&ep->poll_wait)) |
1035 | pwake++; | |
1036 | } | |
1037 | ||
1038 | write_unlock_irqrestore(&ep->lock, flags); | |
1039 | ||
1040 | /* We have to call this outside the lock */ | |
1041 | if (pwake) | |
1042 | ep_poll_safewake(&psw, &ep->poll_wait); | |
1043 | ||
1044 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_insert(%p, %p, %d)\n", | |
1045 | current, ep, tfile, fd)); | |
1046 | ||
1047 | return 0; | |
1048 | ||
1049 | eexit_2: | |
1050 | ep_unregister_pollwait(ep, epi); | |
1051 | ||
1052 | /* | |
1053 | * We need to do this because an event could have been arrived on some | |
1054 | * allocated wait queue. | |
1055 | */ | |
1056 | write_lock_irqsave(&ep->lock, flags); | |
b030a4dd | 1057 | if (ep_is_linked(&epi->rdllink)) |
6192bd53 | 1058 | list_del_init(&epi->rdllink); |
1da177e4 LT |
1059 | write_unlock_irqrestore(&ep->lock, flags); |
1060 | ||
b030a4dd | 1061 | kmem_cache_free(epi_cache, epi); |
1da177e4 LT |
1062 | eexit_1: |
1063 | return error; | |
1064 | } | |
1065 | ||
1066 | ||
1067 | /* | |
1068 | * Modify the interest event mask by dropping an event if the new mask | |
1069 | * has a match in the current file status. | |
1070 | */ | |
1071 | static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_event *event) | |
1072 | { | |
1073 | int pwake = 0; | |
1074 | unsigned int revents; | |
1075 | unsigned long flags; | |
1076 | ||
1077 | /* | |
1078 | * Set the new event interest mask before calling f_op->poll(), otherwise | |
1079 | * a potential race might occur. In fact if we do this operation inside | |
1080 | * the lock, an event might happen between the f_op->poll() call and the | |
1081 | * new event set registering. | |
1082 | */ | |
1083 | epi->event.events = event->events; | |
1084 | ||
1085 | /* | |
1086 | * Get current event bits. We can safely use the file* here because | |
1087 | * its usage count has been increased by the caller of this function. | |
1088 | */ | |
1089 | revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL); | |
1090 | ||
1091 | write_lock_irqsave(&ep->lock, flags); | |
1092 | ||
1093 | /* Copy the data member from inside the lock */ | |
1094 | epi->event.data = event->data; | |
1095 | ||
1096 | /* | |
6192bd53 | 1097 | * If the item is not linked to the RB tree it means that it's on its |
1da177e4 LT |
1098 | * way toward the removal. Do nothing in this case. |
1099 | */ | |
b030a4dd | 1100 | if (ep_rb_linked(&epi->rbn)) { |
1da177e4 LT |
1101 | /* |
1102 | * If the item is "hot" and it is not registered inside the ready | |
1103 | * list, push it inside. If the item is not "hot" and it is currently | |
1104 | * registered inside the ready list, unlink it. | |
1105 | */ | |
1106 | if (revents & event->events) { | |
b030a4dd | 1107 | if (!ep_is_linked(&epi->rdllink)) { |
1da177e4 LT |
1108 | list_add_tail(&epi->rdllink, &ep->rdllist); |
1109 | ||
1110 | /* Notify waiting tasks that events are available */ | |
1111 | if (waitqueue_active(&ep->wq)) | |
3419b23a DL |
1112 | __wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE | |
1113 | TASK_INTERRUPTIBLE); | |
1da177e4 LT |
1114 | if (waitqueue_active(&ep->poll_wait)) |
1115 | pwake++; | |
1116 | } | |
1117 | } | |
1118 | } | |
1119 | ||
1120 | write_unlock_irqrestore(&ep->lock, flags); | |
1121 | ||
1122 | /* We have to call this outside the lock */ | |
1123 | if (pwake) | |
1124 | ep_poll_safewake(&psw, &ep->poll_wait); | |
1125 | ||
1126 | return 0; | |
1127 | } | |
1128 | ||
1129 | ||
1130 | /* | |
1131 | * This function unregister poll callbacks from the associated file descriptor. | |
1132 | * Since this must be called without holding "ep->lock" the atomic exchange trick | |
1133 | * will protect us from multiple unregister. | |
1134 | */ | |
1135 | static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi) | |
1136 | { | |
1137 | int nwait; | |
1138 | struct list_head *lsthead = &epi->pwqlist; | |
1139 | struct eppoll_entry *pwq; | |
1140 | ||
1141 | /* This is called without locks, so we need the atomic exchange */ | |
1142 | nwait = xchg(&epi->nwait, 0); | |
1143 | ||
1144 | if (nwait) { | |
1145 | while (!list_empty(lsthead)) { | |
1146 | pwq = list_entry(lsthead->next, struct eppoll_entry, llink); | |
1147 | ||
6192bd53 | 1148 | list_del_init(&pwq->llink); |
1da177e4 | 1149 | remove_wait_queue(pwq->whead, &pwq->wait); |
b030a4dd | 1150 | kmem_cache_free(pwq_cache, pwq); |
1da177e4 LT |
1151 | } |
1152 | } | |
1153 | } | |
1154 | ||
1155 | ||
1156 | /* | |
1157 | * Unlink the "struct epitem" from all places it might have been hooked up. | |
1158 | * This function must be called with write IRQ lock on "ep->lock". | |
1159 | */ | |
1160 | static int ep_unlink(struct eventpoll *ep, struct epitem *epi) | |
1161 | { | |
1162 | int error; | |
1163 | ||
1164 | /* | |
1165 | * It can happen that this one is called for an item already unlinked. | |
1166 | * The check protect us from doing a double unlink ( crash ). | |
1167 | */ | |
1168 | error = -ENOENT; | |
b030a4dd | 1169 | if (!ep_rb_linked(&epi->rbn)) |
1da177e4 LT |
1170 | goto eexit_1; |
1171 | ||
1172 | /* | |
1173 | * Clear the event mask for the unlinked item. This will avoid item | |
1174 | * notifications to be sent after the unlink operation from inside | |
1175 | * the kernel->userspace event transfer loop. | |
1176 | */ | |
1177 | epi->event.events = 0; | |
1178 | ||
1179 | /* | |
1180 | * At this point is safe to do the job, unlink the item from our rb-tree. | |
1181 | * This operation togheter with the above check closes the door to | |
1182 | * double unlinks. | |
1183 | */ | |
b030a4dd | 1184 | ep_rb_erase(&epi->rbn, &ep->rbr); |
1da177e4 LT |
1185 | |
1186 | /* | |
1187 | * If the item we are going to remove is inside the ready file descriptors | |
1188 | * we want to remove it from this list to avoid stale events. | |
1189 | */ | |
b030a4dd | 1190 | if (ep_is_linked(&epi->rdllink)) |
6192bd53 | 1191 | list_del_init(&epi->rdllink); |
1da177e4 LT |
1192 | |
1193 | error = 0; | |
1194 | eexit_1: | |
1195 | ||
1196 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_unlink(%p, %p) = %d\n", | |
45f17e0c | 1197 | current, ep, epi->ffd.file, error)); |
1da177e4 LT |
1198 | |
1199 | return error; | |
1200 | } | |
1201 | ||
1202 | ||
1203 | /* | |
6192bd53 | 1204 | * Removes a "struct epitem" from the eventpoll RB tree and deallocates |
1da177e4 LT |
1205 | * all the associated resources. |
1206 | */ | |
1207 | static int ep_remove(struct eventpoll *ep, struct epitem *epi) | |
1208 | { | |
1209 | int error; | |
1210 | unsigned long flags; | |
1211 | struct file *file = epi->ffd.file; | |
1212 | ||
1213 | /* | |
1214 | * Removes poll wait queue hooks. We _have_ to do this without holding | |
1215 | * the "ep->lock" otherwise a deadlock might occur. This because of the | |
1216 | * sequence of the lock acquisition. Here we do "ep->lock" then the wait | |
1217 | * queue head lock when unregistering the wait queue. The wakeup callback | |
1218 | * will run by holding the wait queue head lock and will call our callback | |
1219 | * that will try to get "ep->lock". | |
1220 | */ | |
1221 | ep_unregister_pollwait(ep, epi); | |
1222 | ||
1223 | /* Remove the current item from the list of epoll hooks */ | |
1224 | spin_lock(&file->f_ep_lock); | |
b030a4dd | 1225 | if (ep_is_linked(&epi->fllink)) |
6192bd53 | 1226 | list_del_init(&epi->fllink); |
1da177e4 LT |
1227 | spin_unlock(&file->f_ep_lock); |
1228 | ||
1229 | /* We need to acquire the write IRQ lock before calling ep_unlink() */ | |
1230 | write_lock_irqsave(&ep->lock, flags); | |
1231 | ||
6192bd53 | 1232 | /* Really unlink the item from the RB tree */ |
1da177e4 LT |
1233 | error = ep_unlink(ep, epi); |
1234 | ||
1235 | write_unlock_irqrestore(&ep->lock, flags); | |
1236 | ||
1237 | if (error) | |
1238 | goto eexit_1; | |
1239 | ||
1240 | /* At this point it is safe to free the eventpoll item */ | |
1241 | ep_release_epitem(epi); | |
1242 | ||
1243 | error = 0; | |
1244 | eexit_1: | |
1245 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_remove(%p, %p) = %d\n", | |
1246 | current, ep, file, error)); | |
1247 | ||
1248 | return error; | |
1249 | } | |
1250 | ||
1251 | ||
1252 | /* | |
1253 | * This is the callback that is passed to the wait queue wakeup | |
1254 | * machanism. It is called by the stored file descriptors when they | |
1255 | * have events to report. | |
1256 | */ | |
1257 | static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key) | |
1258 | { | |
1259 | int pwake = 0; | |
1260 | unsigned long flags; | |
b030a4dd | 1261 | struct epitem *epi = ep_item_from_wait(wait); |
1da177e4 LT |
1262 | struct eventpoll *ep = epi->ep; |
1263 | ||
1264 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: poll_callback(%p) epi=%p ep=%p\n", | |
45f17e0c | 1265 | current, epi->ffd.file, epi, ep)); |
1da177e4 LT |
1266 | |
1267 | write_lock_irqsave(&ep->lock, flags); | |
1268 | ||
1269 | /* | |
1270 | * If the event mask does not contain any poll(2) event, we consider the | |
1271 | * descriptor to be disabled. This condition is likely the effect of the | |
1272 | * EPOLLONESHOT bit that disables the descriptor when an event is received, | |
1273 | * until the next EPOLL_CTL_MOD will be issued. | |
1274 | */ | |
1275 | if (!(epi->event.events & ~EP_PRIVATE_BITS)) | |
1276 | goto is_disabled; | |
1277 | ||
1278 | /* If this file is already in the ready list we exit soon */ | |
b030a4dd | 1279 | if (ep_is_linked(&epi->rdllink)) |
1da177e4 LT |
1280 | goto is_linked; |
1281 | ||
1282 | list_add_tail(&epi->rdllink, &ep->rdllist); | |
1283 | ||
1284 | is_linked: | |
1285 | /* | |
1286 | * Wake up ( if active ) both the eventpoll wait list and the ->poll() | |
1287 | * wait list. | |
1288 | */ | |
1289 | if (waitqueue_active(&ep->wq)) | |
3419b23a DL |
1290 | __wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE | |
1291 | TASK_INTERRUPTIBLE); | |
1da177e4 LT |
1292 | if (waitqueue_active(&ep->poll_wait)) |
1293 | pwake++; | |
1294 | ||
1295 | is_disabled: | |
1296 | write_unlock_irqrestore(&ep->lock, flags); | |
1297 | ||
1298 | /* We have to call this outside the lock */ | |
1299 | if (pwake) | |
1300 | ep_poll_safewake(&psw, &ep->poll_wait); | |
1301 | ||
1302 | return 1; | |
1303 | } | |
1304 | ||
1305 | ||
1306 | static int ep_eventpoll_close(struct inode *inode, struct file *file) | |
1307 | { | |
1308 | struct eventpoll *ep = file->private_data; | |
1309 | ||
1310 | if (ep) { | |
1311 | ep_free(ep); | |
1312 | kfree(ep); | |
1313 | } | |
1314 | ||
1315 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: close() ep=%p\n", current, ep)); | |
1316 | return 0; | |
1317 | } | |
1318 | ||
1319 | ||
1320 | static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait) | |
1321 | { | |
1322 | unsigned int pollflags = 0; | |
1323 | unsigned long flags; | |
1324 | struct eventpoll *ep = file->private_data; | |
1325 | ||
1326 | /* Insert inside our poll wait queue */ | |
1327 | poll_wait(file, &ep->poll_wait, wait); | |
1328 | ||
1329 | /* Check our condition */ | |
1330 | read_lock_irqsave(&ep->lock, flags); | |
1331 | if (!list_empty(&ep->rdllist)) | |
1332 | pollflags = POLLIN | POLLRDNORM; | |
1333 | read_unlock_irqrestore(&ep->lock, flags); | |
1334 | ||
1335 | return pollflags; | |
1336 | } | |
1337 | ||
1338 | ||
1da177e4 LT |
1339 | /* |
1340 | * This function is called without holding the "ep->lock" since the call to | |
1341 | * __copy_to_user() might sleep, and also f_op->poll() might reenable the IRQ | |
1342 | * because of the way poll() is traditionally implemented in Linux. | |
1343 | */ | |
1344 | static int ep_send_events(struct eventpoll *ep, struct list_head *txlist, | |
6192bd53 | 1345 | struct epoll_event __user *events, int maxevents) |
1da177e4 | 1346 | { |
6192bd53 | 1347 | int eventcnt, error = -EFAULT, pwake = 0; |
1da177e4 | 1348 | unsigned int revents; |
6192bd53 | 1349 | unsigned long flags; |
1da177e4 | 1350 | struct epitem *epi; |
6192bd53 DL |
1351 | struct list_head injlist; |
1352 | ||
1353 | INIT_LIST_HEAD(&injlist); | |
1da177e4 LT |
1354 | |
1355 | /* | |
1356 | * We can loop without lock because this is a task private list. | |
6192bd53 DL |
1357 | * We just splice'd out the ep->rdllist in ep_collect_ready_items(). |
1358 | * Items cannot vanish during the loop because we are holding "sem" in | |
1359 | * read. | |
1da177e4 | 1360 | */ |
6192bd53 DL |
1361 | for (eventcnt = 0; !list_empty(txlist) && eventcnt < maxevents;) { |
1362 | epi = list_entry(txlist->next, struct epitem, rdllink); | |
1363 | prefetch(epi->rdllink.next); | |
1da177e4 LT |
1364 | |
1365 | /* | |
1366 | * Get the ready file event set. We can safely use the file | |
1367 | * because we are holding the "sem" in read and this will | |
1368 | * guarantee that both the file and the item will not vanish. | |
1369 | */ | |
1370 | revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL); | |
6192bd53 | 1371 | revents &= epi->event.events; |
1da177e4 LT |
1372 | |
1373 | /* | |
6192bd53 DL |
1374 | * Is the event mask intersect the caller-requested one, |
1375 | * deliver the event to userspace. Again, we are holding | |
1376 | * "sem" in read, so no operations coming from userspace | |
1377 | * can change the item. | |
1da177e4 | 1378 | */ |
6192bd53 DL |
1379 | if (revents) { |
1380 | if (__put_user(revents, | |
1da177e4 LT |
1381 | &events[eventcnt].events) || |
1382 | __put_user(epi->event.data, | |
1383 | &events[eventcnt].data)) | |
6192bd53 | 1384 | goto errxit; |
1da177e4 LT |
1385 | if (epi->event.events & EPOLLONESHOT) |
1386 | epi->event.events &= EP_PRIVATE_BITS; | |
1387 | eventcnt++; | |
1388 | } | |
1da177e4 LT |
1389 | |
1390 | /* | |
6192bd53 DL |
1391 | * This is tricky. We are holding the "sem" in read, and this |
1392 | * means that the operations that can change the "linked" status | |
1393 | * of the epoll item (epi->rbn and epi->rdllink), cannot touch | |
1394 | * them. Also, since we are "linked" from a epi->rdllink POV | |
1395 | * (the item is linked to our transmission list we just | |
1396 | * spliced), the ep_poll_callback() cannot touch us either, | |
1397 | * because of the check present in there. Another parallel | |
1398 | * epoll_wait() will not get the same result set, since we | |
1399 | * spliced the ready list before. Note that list_del() still | |
1400 | * shows the item as linked to the test in ep_poll_callback(). | |
1da177e4 | 1401 | */ |
6192bd53 DL |
1402 | list_del(&epi->rdllink); |
1403 | if (!(epi->event.events & EPOLLET) && | |
1404 | (revents & epi->event.events)) | |
1405 | list_add_tail(&epi->rdllink, &injlist); | |
1406 | else { | |
1407 | /* | |
1408 | * Be sure the item is totally detached before re-init | |
1409 | * the list_head. After INIT_LIST_HEAD() is committed, | |
1410 | * the ep_poll_callback() can requeue the item again, | |
1411 | * but we don't care since we are already past it. | |
1412 | */ | |
1413 | smp_mb(); | |
1414 | INIT_LIST_HEAD(&epi->rdllink); | |
1da177e4 LT |
1415 | } |
1416 | } | |
6192bd53 | 1417 | error = 0; |
1da177e4 | 1418 | |
6192bd53 DL |
1419 | errxit: |
1420 | ||
1421 | /* | |
1422 | * If the re-injection list or the txlist are not empty, re-splice | |
1423 | * them to the ready list and do proper wakeups. | |
1424 | */ | |
1425 | if (!list_empty(&injlist) || !list_empty(txlist)) { | |
1426 | write_lock_irqsave(&ep->lock, flags); | |
1427 | ||
1428 | list_splice(txlist, &ep->rdllist); | |
1429 | list_splice(&injlist, &ep->rdllist); | |
1da177e4 LT |
1430 | /* |
1431 | * Wake up ( if active ) both the eventpoll wait list and the ->poll() | |
1432 | * wait list. | |
1433 | */ | |
1434 | if (waitqueue_active(&ep->wq)) | |
3419b23a DL |
1435 | __wake_up_locked(&ep->wq, TASK_UNINTERRUPTIBLE | |
1436 | TASK_INTERRUPTIBLE); | |
1da177e4 LT |
1437 | if (waitqueue_active(&ep->poll_wait)) |
1438 | pwake++; | |
1da177e4 | 1439 | |
6192bd53 DL |
1440 | write_unlock_irqrestore(&ep->lock, flags); |
1441 | } | |
1da177e4 LT |
1442 | |
1443 | /* We have to call this outside the lock */ | |
1444 | if (pwake) | |
1445 | ep_poll_safewake(&psw, &ep->poll_wait); | |
6192bd53 DL |
1446 | |
1447 | return eventcnt == 0 ? error: eventcnt; | |
1da177e4 LT |
1448 | } |
1449 | ||
1450 | ||
1451 | /* | |
1452 | * Perform the transfer of events to user space. | |
1453 | */ | |
1454 | static int ep_events_transfer(struct eventpoll *ep, | |
1455 | struct epoll_event __user *events, int maxevents) | |
1456 | { | |
6192bd53 DL |
1457 | int eventcnt; |
1458 | unsigned long flags; | |
1da177e4 LT |
1459 | struct list_head txlist; |
1460 | ||
1461 | INIT_LIST_HEAD(&txlist); | |
1462 | ||
1463 | /* | |
1464 | * We need to lock this because we could be hit by | |
1465 | * eventpoll_release_file() and epoll_ctl(EPOLL_CTL_DEL). | |
1466 | */ | |
1467 | down_read(&ep->sem); | |
1468 | ||
6192bd53 DL |
1469 | /* |
1470 | * Steal the ready list, and re-init the original one to the | |
1471 | * empty list. | |
1472 | */ | |
1473 | write_lock_irqsave(&ep->lock, flags); | |
1474 | list_splice(&ep->rdllist, &txlist); | |
1475 | INIT_LIST_HEAD(&ep->rdllist); | |
1476 | write_unlock_irqrestore(&ep->lock, flags); | |
1da177e4 | 1477 | |
6192bd53 DL |
1478 | /* Build result set in userspace */ |
1479 | eventcnt = ep_send_events(ep, &txlist, events, maxevents); | |
1da177e4 LT |
1480 | |
1481 | up_read(&ep->sem); | |
1482 | ||
1483 | return eventcnt; | |
1484 | } | |
1485 | ||
1486 | ||
1487 | static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, | |
1488 | int maxevents, long timeout) | |
1489 | { | |
1490 | int res, eavail; | |
1491 | unsigned long flags; | |
1492 | long jtimeout; | |
1493 | wait_queue_t wait; | |
1494 | ||
1495 | /* | |
1496 | * Calculate the timeout by checking for the "infinite" value ( -1 ) | |
1497 | * and the overflow condition. The passed timeout is in milliseconds, | |
1498 | * that why (t * HZ) / 1000. | |
1499 | */ | |
e3306dd5 DL |
1500 | jtimeout = (timeout < 0 || timeout >= EP_MAX_MSTIMEO) ? |
1501 | MAX_SCHEDULE_TIMEOUT : (timeout * HZ + 999) / 1000; | |
1da177e4 LT |
1502 | |
1503 | retry: | |
1504 | write_lock_irqsave(&ep->lock, flags); | |
1505 | ||
1506 | res = 0; | |
1507 | if (list_empty(&ep->rdllist)) { | |
1508 | /* | |
1509 | * We don't have any available event to return to the caller. | |
1510 | * We need to sleep here, and we will be wake up by | |
1511 | * ep_poll_callback() when events will become available. | |
1512 | */ | |
1513 | init_waitqueue_entry(&wait, current); | |
3419b23a | 1514 | __add_wait_queue(&ep->wq, &wait); |
1da177e4 LT |
1515 | |
1516 | for (;;) { | |
1517 | /* | |
1518 | * We don't want to sleep if the ep_poll_callback() sends us | |
1519 | * a wakeup in between. That's why we set the task state | |
1520 | * to TASK_INTERRUPTIBLE before doing the checks. | |
1521 | */ | |
1522 | set_current_state(TASK_INTERRUPTIBLE); | |
1523 | if (!list_empty(&ep->rdllist) || !jtimeout) | |
1524 | break; | |
1525 | if (signal_pending(current)) { | |
1526 | res = -EINTR; | |
1527 | break; | |
1528 | } | |
1529 | ||
1530 | write_unlock_irqrestore(&ep->lock, flags); | |
1531 | jtimeout = schedule_timeout(jtimeout); | |
1532 | write_lock_irqsave(&ep->lock, flags); | |
1533 | } | |
3419b23a | 1534 | __remove_wait_queue(&ep->wq, &wait); |
1da177e4 LT |
1535 | |
1536 | set_current_state(TASK_RUNNING); | |
1537 | } | |
1538 | ||
1539 | /* Is it worth to try to dig for events ? */ | |
1540 | eavail = !list_empty(&ep->rdllist); | |
1541 | ||
1542 | write_unlock_irqrestore(&ep->lock, flags); | |
1543 | ||
1544 | /* | |
1545 | * Try to transfer events to user space. In case we get 0 events and | |
1546 | * there's still timeout left over, we go trying again in search of | |
1547 | * more luck. | |
1548 | */ | |
1549 | if (!res && eavail && | |
1550 | !(res = ep_events_transfer(ep, events, maxevents)) && jtimeout) | |
1551 | goto retry; | |
1552 | ||
1553 | return res; | |
1554 | } | |
1555 | ||
1da177e4 LT |
1556 | static int eventpollfs_delete_dentry(struct dentry *dentry) |
1557 | { | |
1558 | ||
1559 | return 1; | |
1560 | } | |
1561 | ||
1da177e4 LT |
1562 | static struct inode *ep_eventpoll_inode(void) |
1563 | { | |
1564 | int error = -ENOMEM; | |
1565 | struct inode *inode = new_inode(eventpoll_mnt->mnt_sb); | |
1566 | ||
1567 | if (!inode) | |
1568 | goto eexit_1; | |
1569 | ||
1570 | inode->i_fop = &eventpoll_fops; | |
1571 | ||
1572 | /* | |
1573 | * Mark the inode dirty from the very beginning, | |
1574 | * that way it will never be moved to the dirty | |
1575 | * list because mark_inode_dirty() will think | |
1576 | * that it already _is_ on the dirty list. | |
1577 | */ | |
1578 | inode->i_state = I_DIRTY; | |
1579 | inode->i_mode = S_IRUSR | S_IWUSR; | |
1580 | inode->i_uid = current->fsuid; | |
1581 | inode->i_gid = current->fsgid; | |
1582 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
1da177e4 LT |
1583 | return inode; |
1584 | ||
1585 | eexit_1: | |
1586 | return ERR_PTR(error); | |
1587 | } | |
1588 | ||
454e2398 | 1589 | static int |
1da177e4 | 1590 | eventpollfs_get_sb(struct file_system_type *fs_type, int flags, |
454e2398 | 1591 | const char *dev_name, void *data, struct vfsmount *mnt) |
1da177e4 | 1592 | { |
454e2398 DH |
1593 | return get_sb_pseudo(fs_type, "eventpoll:", NULL, EVENTPOLLFS_MAGIC, |
1594 | mnt); | |
1da177e4 LT |
1595 | } |
1596 | ||
1597 | ||
1598 | static int __init eventpoll_init(void) | |
1599 | { | |
1600 | int error; | |
1601 | ||
144efe3e | 1602 | mutex_init(&epmutex); |
1da177e4 LT |
1603 | |
1604 | /* Initialize the structure used to perform safe poll wait head wake ups */ | |
1605 | ep_poll_safewake_init(&psw); | |
1606 | ||
1607 | /* Allocates slab cache used to allocate "struct epitem" items */ | |
1608 | epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem), | |
1609 | 0, SLAB_HWCACHE_ALIGN|EPI_SLAB_DEBUG|SLAB_PANIC, | |
1610 | NULL, NULL); | |
1611 | ||
1612 | /* Allocates slab cache used to allocate "struct eppoll_entry" */ | |
1613 | pwq_cache = kmem_cache_create("eventpoll_pwq", | |
1614 | sizeof(struct eppoll_entry), 0, | |
1615 | EPI_SLAB_DEBUG|SLAB_PANIC, NULL, NULL); | |
1616 | ||
1617 | /* | |
1618 | * Register the virtual file system that will be the source of inodes | |
1619 | * for the eventpoll files | |
1620 | */ | |
1621 | error = register_filesystem(&eventpoll_fs_type); | |
1622 | if (error) | |
1623 | goto epanic; | |
1624 | ||
1625 | /* Mount the above commented virtual file system */ | |
1626 | eventpoll_mnt = kern_mount(&eventpoll_fs_type); | |
1627 | error = PTR_ERR(eventpoll_mnt); | |
1628 | if (IS_ERR(eventpoll_mnt)) | |
1629 | goto epanic; | |
1630 | ||
1631 | DNPRINTK(3, (KERN_INFO "[%p] eventpoll: successfully initialized.\n", | |
1632 | current)); | |
1633 | return 0; | |
1634 | ||
1635 | epanic: | |
1636 | panic("eventpoll_init() failed\n"); | |
1637 | } | |
1638 | ||
1639 | ||
1640 | static void __exit eventpoll_exit(void) | |
1641 | { | |
1642 | /* Undo all operations done inside eventpoll_init() */ | |
1643 | unregister_filesystem(&eventpoll_fs_type); | |
1644 | mntput(eventpoll_mnt); | |
1645 | kmem_cache_destroy(pwq_cache); | |
1646 | kmem_cache_destroy(epi_cache); | |
1647 | } | |
1648 | ||
1649 | module_init(eventpoll_init); | |
1650 | module_exit(eventpoll_exit); | |
1651 | ||
1652 | MODULE_LICENSE("GPL"); |