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9#include <linux/module.h>
10#include <linux/fs.h>
11#include <linux/mm.h>
12#include <linux/time.h>
13#include <linux/sched.h>
14#include <linux/slab.h>
15#include <linux/vmalloc.h>
16#include <linux/file.h>
17#include <linux/fdtable.h>
18#include <linux/bitops.h>
19#include <linux/interrupt.h>
20#include <linux/spinlock.h>
21#include <linux/rcupdate.h>
22#include <linux/workqueue.h>
23
24struct fdtable_defer {
25 spinlock_t lock;
26 struct work_struct wq;
27 struct fdtable *next;
28};
29
30int sysctl_nr_open __read_mostly = 1024*1024;
31int sysctl_nr_open_min = BITS_PER_LONG;
32int sysctl_nr_open_max = 1024 * 1024;
33
34
35
36
37
38
39
40static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list);
41
42static inline void *alloc_fdmem(unsigned int size)
43{
44 void *data;
45
46 data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN);
47 if (data != NULL)
48 return data;
49
50 return vmalloc(size);
51}
52
53static void free_fdmem(void *ptr)
54{
55 is_vmalloc_addr(ptr) ? vfree(ptr) : kfree(ptr);
56}
57
58static void __free_fdtable(struct fdtable *fdt)
59{
60 free_fdmem(fdt->fd);
61 free_fdmem(fdt->open_fds);
62 kfree(fdt);
63}
64
65static void free_fdtable_work(struct work_struct *work)
66{
67 struct fdtable_defer *f =
68 container_of(work, struct fdtable_defer, wq);
69 struct fdtable *fdt;
70
71 spin_lock_bh(&f->lock);
72 fdt = f->next;
73 f->next = NULL;
74 spin_unlock_bh(&f->lock);
75 while(fdt) {
76 struct fdtable *next = fdt->next;
77
78 __free_fdtable(fdt);
79 fdt = next;
80 }
81}
82
83void free_fdtable_rcu(struct rcu_head *rcu)
84{
85 struct fdtable *fdt = container_of(rcu, struct fdtable, rcu);
86 struct fdtable_defer *fddef;
87
88 BUG_ON(!fdt);
89
90 if (fdt->max_fds <= NR_OPEN_DEFAULT) {
91
92
93
94
95 kmem_cache_free(files_cachep,
96 container_of(fdt, struct files_struct, fdtab));
97 return;
98 }
99 if (!is_vmalloc_addr(fdt->fd) && !is_vmalloc_addr(fdt->open_fds)) {
100 kfree(fdt->fd);
101 kfree(fdt->open_fds);
102 kfree(fdt);
103 } else {
104 fddef = &get_cpu_var(fdtable_defer_list);
105 spin_lock(&fddef->lock);
106 fdt->next = fddef->next;
107 fddef->next = fdt;
108
109 schedule_work(&fddef->wq);
110 spin_unlock(&fddef->lock);
111 put_cpu_var(fdtable_defer_list);
112 }
113}
114
115
116
117
118
119static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt)
120{
121 unsigned int cpy, set;
122
123 BUG_ON(nfdt->max_fds < ofdt->max_fds);
124
125 cpy = ofdt->max_fds * sizeof(struct file *);
126 set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);
127 memcpy(nfdt->fd, ofdt->fd, cpy);
128 memset((char *)(nfdt->fd) + cpy, 0, set);
129
130 cpy = ofdt->max_fds / BITS_PER_BYTE;
131 set = (nfdt->max_fds - ofdt->max_fds) / BITS_PER_BYTE;
132 memcpy(nfdt->open_fds, ofdt->open_fds, cpy);
133 memset((char *)(nfdt->open_fds) + cpy, 0, set);
134 memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy);
135 memset((char *)(nfdt->close_on_exec) + cpy, 0, set);
136}
137
138static struct fdtable * alloc_fdtable(unsigned int nr)
139{
140 struct fdtable *fdt;
141 char *data;
142
143
144
145
146
147
148
149
150 nr /= (1024 / sizeof(struct file *));
151 nr = roundup_pow_of_two(nr + 1);
152 nr *= (1024 / sizeof(struct file *));
153
154
155
156
157
158
159
160
161 if (unlikely(nr > sysctl_nr_open))
162 nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1;
163
164 fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL);
165 if (!fdt)
166 goto out;
167 fdt->max_fds = nr;
168 data = alloc_fdmem(nr * sizeof(struct file *));
169 if (!data)
170 goto out_fdt;
171 fdt->fd = (struct file **)data;
172 data = alloc_fdmem(max_t(unsigned int,
173 2 * nr / BITS_PER_BYTE, L1_CACHE_BYTES));
174 if (!data)
175 goto out_arr;
176 fdt->open_fds = (fd_set *)data;
177 data += nr / BITS_PER_BYTE;
178 fdt->close_on_exec = (fd_set *)data;
179 fdt->next = NULL;
180
181 return fdt;
182
183out_arr:
184 free_fdmem(fdt->fd);
185out_fdt:
186 kfree(fdt);
187out:
188 return NULL;
189}
190
191
192
193
194
195
196
197
198static int expand_fdtable(struct files_struct *files, int nr)
199 __releases(files->file_lock)
200 __acquires(files->file_lock)
201{
202 struct fdtable *new_fdt, *cur_fdt;
203
204 spin_unlock(&files->file_lock);
205 new_fdt = alloc_fdtable(nr);
206 spin_lock(&files->file_lock);
207 if (!new_fdt)
208 return -ENOMEM;
209
210
211
212
213 if (unlikely(new_fdt->max_fds <= nr)) {
214 __free_fdtable(new_fdt);
215 return -EMFILE;
216 }
217
218
219
220
221 cur_fdt = files_fdtable(files);
222 if (nr >= cur_fdt->max_fds) {
223
224 copy_fdtable(new_fdt, cur_fdt);
225 rcu_assign_pointer(files->fdt, new_fdt);
226 if (cur_fdt->max_fds > NR_OPEN_DEFAULT)
227 free_fdtable(cur_fdt);
228 } else {
229
230 __free_fdtable(new_fdt);
231 }
232 return 1;
233}
234
235
236
237
238
239
240
241
242
243int expand_files(struct files_struct *files, int nr)
244{
245 struct fdtable *fdt;
246
247 fdt = files_fdtable(files);
248
249
250
251
252
253 if (nr >= rlimit(RLIMIT_NOFILE))
254 return -EMFILE;
255
256
257 if (nr < fdt->max_fds)
258 return 0;
259
260
261 if (nr >= sysctl_nr_open)
262 return -EMFILE;
263
264
265 return expand_fdtable(files, nr);
266}
267
268static int count_open_files(struct fdtable *fdt)
269{
270 int size = fdt->max_fds;
271 int i;
272
273
274 for (i = size/(8*sizeof(long)); i > 0; ) {
275 if (fdt->open_fds->fds_bits[--i])
276 break;
277 }
278 i = (i+1) * 8 * sizeof(long);
279 return i;
280}
281
282
283
284
285
286
287struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
288{
289 struct files_struct *newf;
290 struct file **old_fds, **new_fds;
291 int open_files, size, i;
292 struct fdtable *old_fdt, *new_fdt;
293
294 *errorp = -ENOMEM;
295 newf = kmem_cache_alloc(files_cachep, GFP_KERNEL);
296 if (!newf)
297 goto out;
298
299 atomic_set(&newf->count, 1);
300
301 spin_lock_init(&newf->file_lock);
302 newf->next_fd = 0;
303 new_fdt = &newf->fdtab;
304 new_fdt->max_fds = NR_OPEN_DEFAULT;
305 new_fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init;
306 new_fdt->open_fds = (fd_set *)&newf->open_fds_init;
307 new_fdt->fd = &newf->fd_array[0];
308 new_fdt->next = NULL;
309
310 spin_lock(&oldf->file_lock);
311 old_fdt = files_fdtable(oldf);
312 open_files = count_open_files(old_fdt);
313
314
315
316
317 while (unlikely(open_files > new_fdt->max_fds)) {
318 spin_unlock(&oldf->file_lock);
319
320 if (new_fdt != &newf->fdtab)
321 __free_fdtable(new_fdt);
322
323 new_fdt = alloc_fdtable(open_files - 1);
324 if (!new_fdt) {
325 *errorp = -ENOMEM;
326 goto out_release;
327 }
328
329
330 if (unlikely(new_fdt->max_fds < open_files)) {
331 __free_fdtable(new_fdt);
332 *errorp = -EMFILE;
333 goto out_release;
334 }
335
336
337
338
339
340
341 spin_lock(&oldf->file_lock);
342 old_fdt = files_fdtable(oldf);
343 open_files = count_open_files(old_fdt);
344 }
345
346 old_fds = old_fdt->fd;
347 new_fds = new_fdt->fd;
348
349 memcpy(new_fdt->open_fds->fds_bits,
350 old_fdt->open_fds->fds_bits, open_files/8);
351 memcpy(new_fdt->close_on_exec->fds_bits,
352 old_fdt->close_on_exec->fds_bits, open_files/8);
353
354 for (i = open_files; i != 0; i--) {
355 struct file *f = *old_fds++;
356 if (f) {
357 get_file(f);
358 } else {
359
360
361
362
363
364
365 FD_CLR(open_files - i, new_fdt->open_fds);
366 }
367 rcu_assign_pointer(*new_fds++, f);
368 }
369 spin_unlock(&oldf->file_lock);
370
371
372 size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
373
374
375 memset(new_fds, 0, size);
376
377 if (new_fdt->max_fds > open_files) {
378 int left = (new_fdt->max_fds-open_files)/8;
379 int start = open_files / (8 * sizeof(unsigned long));
380
381 memset(&new_fdt->open_fds->fds_bits[start], 0, left);
382 memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
383 }
384
385 rcu_assign_pointer(newf->fdt, new_fdt);
386
387 return newf;
388
389out_release:
390 kmem_cache_free(files_cachep, newf);
391out:
392 return NULL;
393}
394
395static void __devinit fdtable_defer_list_init(int cpu)
396{
397 struct fdtable_defer *fddef = &per_cpu(fdtable_defer_list, cpu);
398 spin_lock_init(&fddef->lock);
399 INIT_WORK(&fddef->wq, free_fdtable_work);
400 fddef->next = NULL;
401}
402
403void __init files_defer_init(void)
404{
405 int i;
406 for_each_possible_cpu(i)
407 fdtable_defer_list_init(i);
408 sysctl_nr_open_max = min((size_t)INT_MAX, ~(size_t)0/sizeof(void *)) &
409 -BITS_PER_LONG;
410}
411
412struct files_struct init_files = {
413 .count = ATOMIC_INIT(1),
414 .fdt = &init_files.fdtab,
415 .fdtab = {
416 .max_fds = NR_OPEN_DEFAULT,
417 .fd = &init_files.fd_array[0],
418 .close_on_exec = (fd_set *)&init_files.close_on_exec_init,
419 .open_fds = (fd_set *)&init_files.open_fds_init,
420 },
421 .file_lock = __SPIN_LOCK_UNLOCKED(init_task.file_lock),
422};
423
424
425
426
427int alloc_fd(unsigned start, unsigned flags)
428{
429 struct files_struct *files = current->files;
430 unsigned int fd;
431 int error;
432 struct fdtable *fdt;
433
434 spin_lock(&files->file_lock);
435repeat:
436 fdt = files_fdtable(files);
437 fd = start;
438 if (fd < files->next_fd)
439 fd = files->next_fd;
440
441 if (fd < fdt->max_fds)
442 fd = find_next_zero_bit(fdt->open_fds->fds_bits,
443 fdt->max_fds, fd);
444
445 error = expand_files(files, fd);
446 if (error < 0)
447 goto out;
448
449
450
451
452
453 if (error)
454 goto repeat;
455
456 if (start <= files->next_fd)
457 files->next_fd = fd + 1;
458
459 FD_SET(fd, fdt->open_fds);
460 if (flags & O_CLOEXEC)
461 FD_SET(fd, fdt->close_on_exec);
462 else
463 FD_CLR(fd, fdt->close_on_exec);
464 error = fd;
465#if 1
466
467 if (rcu_dereference_raw(fdt->fd[fd]) != NULL) {
468 printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
469 rcu_assign_pointer(fdt->fd[fd], NULL);
470 }
471#endif
472
473out:
474 spin_unlock(&files->file_lock);
475 return error;
476}
477
478int get_unused_fd(void)
479{
480 return alloc_fd(0, 0);
481}
482EXPORT_SYMBOL(get_unused_fd);
483