Commit | Line | Data |
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55716d26 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
b8441ed2 TH |
2 | /* |
3 | * fs/kernfs/file.c - kernfs file implementation | |
4 | * | |
5 | * Copyright (c) 2001-3 Patrick Mochel | |
6 | * Copyright (c) 2007 SUSE Linux Products GmbH | |
7 | * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> | |
b8441ed2 | 8 | */ |
414985ae TH |
9 | |
10 | #include <linux/fs.h> | |
11 | #include <linux/seq_file.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/poll.h> | |
14 | #include <linux/pagemap.h> | |
589ee628 | 15 | #include <linux/sched/mm.h> |
d911d987 | 16 | #include <linux/fsnotify.h> |
414985ae TH |
17 | |
18 | #include "kernfs-internal.h" | |
19 | ||
20 | /* | |
c525aadd | 21 | * There's one kernfs_open_file for each open file and one kernfs_open_node |
324a56e1 | 22 | * for each kernfs_node with one or more open files. |
414985ae | 23 | * |
c525aadd TH |
24 | * kernfs_node->attr.open points to kernfs_open_node. attr.open is |
25 | * protected by kernfs_open_node_lock. | |
414985ae TH |
26 | * |
27 | * filp->private_data points to seq_file whose ->private points to | |
c525aadd TH |
28 | * kernfs_open_file. kernfs_open_files are chained at |
29 | * kernfs_open_node->files, which is protected by kernfs_open_file_mutex. | |
414985ae | 30 | */ |
c525aadd TH |
31 | static DEFINE_SPINLOCK(kernfs_open_node_lock); |
32 | static DEFINE_MUTEX(kernfs_open_file_mutex); | |
414985ae | 33 | |
c525aadd | 34 | struct kernfs_open_node { |
414985ae TH |
35 | atomic_t refcnt; |
36 | atomic_t event; | |
37 | wait_queue_head_t poll; | |
c525aadd | 38 | struct list_head files; /* goes through kernfs_open_file.list */ |
414985ae TH |
39 | }; |
40 | ||
ecca47ce TH |
41 | /* |
42 | * kernfs_notify() may be called from any context and bounces notifications | |
43 | * through a work item. To minimize space overhead in kernfs_node, the | |
44 | * pending queue is implemented as a singly linked list of kernfs_nodes. | |
45 | * The list is terminated with the self pointer so that whether a | |
46 | * kernfs_node is on the list or not can be determined by testing the next | |
47 | * pointer for NULL. | |
48 | */ | |
49 | #define KERNFS_NOTIFY_EOL ((void *)&kernfs_notify_list) | |
50 | ||
51 | static DEFINE_SPINLOCK(kernfs_notify_lock); | |
52 | static struct kernfs_node *kernfs_notify_list = KERNFS_NOTIFY_EOL; | |
53 | ||
c525aadd | 54 | static struct kernfs_open_file *kernfs_of(struct file *file) |
414985ae TH |
55 | { |
56 | return ((struct seq_file *)file->private_data)->private; | |
57 | } | |
58 | ||
59 | /* | |
324a56e1 | 60 | * Determine the kernfs_ops for the given kernfs_node. This function must |
414985ae TH |
61 | * be called while holding an active reference. |
62 | */ | |
324a56e1 | 63 | static const struct kernfs_ops *kernfs_ops(struct kernfs_node *kn) |
414985ae | 64 | { |
df23fc39 | 65 | if (kn->flags & KERNFS_LOCKDEP) |
324a56e1 | 66 | lockdep_assert_held(kn); |
adc5e8b5 | 67 | return kn->attr.ops; |
414985ae TH |
68 | } |
69 | ||
bb305947 TH |
70 | /* |
71 | * As kernfs_seq_stop() is also called after kernfs_seq_start() or | |
72 | * kernfs_seq_next() failure, it needs to distinguish whether it's stopping | |
73 | * a seq_file iteration which is fully initialized with an active reference | |
74 | * or an aborted kernfs_seq_start() due to get_active failure. The | |
75 | * position pointer is the only context for each seq_file iteration and | |
76 | * thus the stop condition should be encoded in it. As the return value is | |
77 | * directly visible to userland, ERR_PTR(-ENODEV) is the only acceptable | |
78 | * choice to indicate get_active failure. | |
79 | * | |
80 | * Unfortunately, this is complicated due to the optional custom seq_file | |
81 | * operations which may return ERR_PTR(-ENODEV) too. kernfs_seq_stop() | |
82 | * can't distinguish whether ERR_PTR(-ENODEV) is from get_active failure or | |
83 | * custom seq_file operations and thus can't decide whether put_active | |
84 | * should be performed or not only on ERR_PTR(-ENODEV). | |
85 | * | |
86 | * This is worked around by factoring out the custom seq_stop() and | |
87 | * put_active part into kernfs_seq_stop_active(), skipping it from | |
88 | * kernfs_seq_stop() if ERR_PTR(-ENODEV) while invoking it directly after | |
89 | * custom seq_file operations fail with ERR_PTR(-ENODEV) - this ensures | |
90 | * that kernfs_seq_stop_active() is skipped only after get_active failure. | |
91 | */ | |
92 | static void kernfs_seq_stop_active(struct seq_file *sf, void *v) | |
93 | { | |
94 | struct kernfs_open_file *of = sf->private; | |
95 | const struct kernfs_ops *ops = kernfs_ops(of->kn); | |
96 | ||
97 | if (ops->seq_stop) | |
98 | ops->seq_stop(sf, v); | |
99 | kernfs_put_active(of->kn); | |
100 | } | |
101 | ||
414985ae TH |
102 | static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos) |
103 | { | |
c525aadd | 104 | struct kernfs_open_file *of = sf->private; |
414985ae TH |
105 | const struct kernfs_ops *ops; |
106 | ||
107 | /* | |
2b75869b | 108 | * @of->mutex nests outside active ref and is primarily to ensure that |
414985ae TH |
109 | * the ops aren't called concurrently for the same open file. |
110 | */ | |
111 | mutex_lock(&of->mutex); | |
c637b8ac | 112 | if (!kernfs_get_active(of->kn)) |
414985ae TH |
113 | return ERR_PTR(-ENODEV); |
114 | ||
324a56e1 | 115 | ops = kernfs_ops(of->kn); |
414985ae | 116 | if (ops->seq_start) { |
bb305947 TH |
117 | void *next = ops->seq_start(sf, ppos); |
118 | /* see the comment above kernfs_seq_stop_active() */ | |
119 | if (next == ERR_PTR(-ENODEV)) | |
120 | kernfs_seq_stop_active(sf, next); | |
121 | return next; | |
414985ae TH |
122 | } else { |
123 | /* | |
124 | * The same behavior and code as single_open(). Returns | |
125 | * !NULL if pos is at the beginning; otherwise, NULL. | |
126 | */ | |
127 | return NULL + !*ppos; | |
128 | } | |
129 | } | |
130 | ||
131 | static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos) | |
132 | { | |
c525aadd | 133 | struct kernfs_open_file *of = sf->private; |
324a56e1 | 134 | const struct kernfs_ops *ops = kernfs_ops(of->kn); |
414985ae TH |
135 | |
136 | if (ops->seq_next) { | |
bb305947 TH |
137 | void *next = ops->seq_next(sf, v, ppos); |
138 | /* see the comment above kernfs_seq_stop_active() */ | |
139 | if (next == ERR_PTR(-ENODEV)) | |
140 | kernfs_seq_stop_active(sf, next); | |
141 | return next; | |
414985ae TH |
142 | } else { |
143 | /* | |
144 | * The same behavior and code as single_open(), always | |
145 | * terminate after the initial read. | |
146 | */ | |
147 | ++*ppos; | |
148 | return NULL; | |
149 | } | |
150 | } | |
151 | ||
152 | static void kernfs_seq_stop(struct seq_file *sf, void *v) | |
153 | { | |
c525aadd | 154 | struct kernfs_open_file *of = sf->private; |
414985ae | 155 | |
bb305947 TH |
156 | if (v != ERR_PTR(-ENODEV)) |
157 | kernfs_seq_stop_active(sf, v); | |
414985ae TH |
158 | mutex_unlock(&of->mutex); |
159 | } | |
160 | ||
161 | static int kernfs_seq_show(struct seq_file *sf, void *v) | |
162 | { | |
c525aadd | 163 | struct kernfs_open_file *of = sf->private; |
414985ae | 164 | |
adc5e8b5 | 165 | of->event = atomic_read(&of->kn->attr.open->event); |
414985ae | 166 | |
adc5e8b5 | 167 | return of->kn->attr.ops->seq_show(sf, v); |
414985ae TH |
168 | } |
169 | ||
170 | static const struct seq_operations kernfs_seq_ops = { | |
171 | .start = kernfs_seq_start, | |
172 | .next = kernfs_seq_next, | |
173 | .stop = kernfs_seq_stop, | |
174 | .show = kernfs_seq_show, | |
175 | }; | |
176 | ||
177 | /* | |
178 | * As reading a bin file can have side-effects, the exact offset and bytes | |
179 | * specified in read(2) call should be passed to the read callback making | |
180 | * it difficult to use seq_file. Implement simplistic custom buffering for | |
181 | * bin files. | |
182 | */ | |
c525aadd | 183 | static ssize_t kernfs_file_direct_read(struct kernfs_open_file *of, |
414985ae TH |
184 | char __user *user_buf, size_t count, |
185 | loff_t *ppos) | |
186 | { | |
187 | ssize_t len = min_t(size_t, count, PAGE_SIZE); | |
188 | const struct kernfs_ops *ops; | |
189 | char *buf; | |
190 | ||
4ef67a8c | 191 | buf = of->prealloc_buf; |
e4234a1f CW |
192 | if (buf) |
193 | mutex_lock(&of->prealloc_mutex); | |
194 | else | |
4ef67a8c | 195 | buf = kmalloc(len, GFP_KERNEL); |
414985ae TH |
196 | if (!buf) |
197 | return -ENOMEM; | |
198 | ||
199 | /* | |
4ef67a8c | 200 | * @of->mutex nests outside active ref and is used both to ensure that |
e4234a1f | 201 | * the ops aren't called concurrently for the same open file. |
414985ae TH |
202 | */ |
203 | mutex_lock(&of->mutex); | |
c637b8ac | 204 | if (!kernfs_get_active(of->kn)) { |
414985ae TH |
205 | len = -ENODEV; |
206 | mutex_unlock(&of->mutex); | |
207 | goto out_free; | |
208 | } | |
209 | ||
7cff4b18 | 210 | of->event = atomic_read(&of->kn->attr.open->event); |
324a56e1 | 211 | ops = kernfs_ops(of->kn); |
414985ae TH |
212 | if (ops->read) |
213 | len = ops->read(of, buf, len, *ppos); | |
214 | else | |
215 | len = -EINVAL; | |
216 | ||
e4234a1f CW |
217 | kernfs_put_active(of->kn); |
218 | mutex_unlock(&of->mutex); | |
219 | ||
414985ae | 220 | if (len < 0) |
e4234a1f | 221 | goto out_free; |
414985ae TH |
222 | |
223 | if (copy_to_user(user_buf, buf, len)) { | |
224 | len = -EFAULT; | |
e4234a1f | 225 | goto out_free; |
414985ae TH |
226 | } |
227 | ||
228 | *ppos += len; | |
229 | ||
230 | out_free: | |
e4234a1f CW |
231 | if (buf == of->prealloc_buf) |
232 | mutex_unlock(&of->prealloc_mutex); | |
233 | else | |
4ef67a8c | 234 | kfree(buf); |
414985ae TH |
235 | return len; |
236 | } | |
237 | ||
238 | /** | |
c637b8ac | 239 | * kernfs_fop_read - kernfs vfs read callback |
414985ae TH |
240 | * @file: file pointer |
241 | * @user_buf: data to write | |
242 | * @count: number of bytes | |
243 | * @ppos: starting offset | |
244 | */ | |
c637b8ac TH |
245 | static ssize_t kernfs_fop_read(struct file *file, char __user *user_buf, |
246 | size_t count, loff_t *ppos) | |
414985ae | 247 | { |
c525aadd | 248 | struct kernfs_open_file *of = kernfs_of(file); |
414985ae | 249 | |
df23fc39 | 250 | if (of->kn->flags & KERNFS_HAS_SEQ_SHOW) |
414985ae TH |
251 | return seq_read(file, user_buf, count, ppos); |
252 | else | |
253 | return kernfs_file_direct_read(of, user_buf, count, ppos); | |
254 | } | |
255 | ||
256 | /** | |
c637b8ac | 257 | * kernfs_fop_write - kernfs vfs write callback |
414985ae TH |
258 | * @file: file pointer |
259 | * @user_buf: data to write | |
260 | * @count: number of bytes | |
261 | * @ppos: starting offset | |
262 | * | |
263 | * Copy data in from userland and pass it to the matching kernfs write | |
264 | * operation. | |
265 | * | |
266 | * There is no easy way for us to know if userspace is only doing a partial | |
267 | * write, so we don't support them. We expect the entire buffer to come on | |
268 | * the first write. Hint: if you're writing a value, first read the file, | |
269 | * modify only the the value you're changing, then write entire buffer | |
270 | * back. | |
271 | */ | |
c637b8ac TH |
272 | static ssize_t kernfs_fop_write(struct file *file, const char __user *user_buf, |
273 | size_t count, loff_t *ppos) | |
414985ae | 274 | { |
c525aadd | 275 | struct kernfs_open_file *of = kernfs_of(file); |
414985ae | 276 | const struct kernfs_ops *ops; |
ba87977a | 277 | ssize_t len; |
b7ce40cf | 278 | char *buf; |
4d3773c4 | 279 | |
b7ce40cf | 280 | if (of->atomic_write_len) { |
4d3773c4 | 281 | len = count; |
b7ce40cf TH |
282 | if (len > of->atomic_write_len) |
283 | return -E2BIG; | |
4d3773c4 TH |
284 | } else { |
285 | len = min_t(size_t, count, PAGE_SIZE); | |
286 | } | |
287 | ||
2b75869b | 288 | buf = of->prealloc_buf; |
e4234a1f CW |
289 | if (buf) |
290 | mutex_lock(&of->prealloc_mutex); | |
291 | else | |
2b75869b | 292 | buf = kmalloc(len + 1, GFP_KERNEL); |
b7ce40cf TH |
293 | if (!buf) |
294 | return -ENOMEM; | |
414985ae | 295 | |
e4234a1f CW |
296 | if (copy_from_user(buf, user_buf, len)) { |
297 | len = -EFAULT; | |
298 | goto out_free; | |
299 | } | |
300 | buf[len] = '\0'; /* guarantee string termination */ | |
301 | ||
b7ce40cf | 302 | /* |
2b75869b | 303 | * @of->mutex nests outside active ref and is used both to ensure that |
e4234a1f | 304 | * the ops aren't called concurrently for the same open file. |
b7ce40cf TH |
305 | */ |
306 | mutex_lock(&of->mutex); | |
307 | if (!kernfs_get_active(of->kn)) { | |
308 | mutex_unlock(&of->mutex); | |
309 | len = -ENODEV; | |
310 | goto out_free; | |
311 | } | |
312 | ||
313 | ops = kernfs_ops(of->kn); | |
314 | if (ops->write) | |
315 | len = ops->write(of, buf, len, *ppos); | |
316 | else | |
317 | len = -EINVAL; | |
318 | ||
e4234a1f CW |
319 | kernfs_put_active(of->kn); |
320 | mutex_unlock(&of->mutex); | |
321 | ||
414985ae TH |
322 | if (len > 0) |
323 | *ppos += len; | |
2b75869b | 324 | |
b7ce40cf | 325 | out_free: |
e4234a1f CW |
326 | if (buf == of->prealloc_buf) |
327 | mutex_unlock(&of->prealloc_mutex); | |
328 | else | |
2b75869b | 329 | kfree(buf); |
414985ae TH |
330 | return len; |
331 | } | |
332 | ||
333 | static void kernfs_vma_open(struct vm_area_struct *vma) | |
334 | { | |
335 | struct file *file = vma->vm_file; | |
c525aadd | 336 | struct kernfs_open_file *of = kernfs_of(file); |
414985ae TH |
337 | |
338 | if (!of->vm_ops) | |
339 | return; | |
340 | ||
c637b8ac | 341 | if (!kernfs_get_active(of->kn)) |
414985ae TH |
342 | return; |
343 | ||
344 | if (of->vm_ops->open) | |
345 | of->vm_ops->open(vma); | |
346 | ||
c637b8ac | 347 | kernfs_put_active(of->kn); |
414985ae TH |
348 | } |
349 | ||
9ee84466 | 350 | static vm_fault_t kernfs_vma_fault(struct vm_fault *vmf) |
414985ae | 351 | { |
11bac800 | 352 | struct file *file = vmf->vma->vm_file; |
c525aadd | 353 | struct kernfs_open_file *of = kernfs_of(file); |
9ee84466 | 354 | vm_fault_t ret; |
414985ae TH |
355 | |
356 | if (!of->vm_ops) | |
357 | return VM_FAULT_SIGBUS; | |
358 | ||
c637b8ac | 359 | if (!kernfs_get_active(of->kn)) |
414985ae TH |
360 | return VM_FAULT_SIGBUS; |
361 | ||
362 | ret = VM_FAULT_SIGBUS; | |
363 | if (of->vm_ops->fault) | |
11bac800 | 364 | ret = of->vm_ops->fault(vmf); |
414985ae | 365 | |
c637b8ac | 366 | kernfs_put_active(of->kn); |
414985ae TH |
367 | return ret; |
368 | } | |
369 | ||
9ee84466 | 370 | static vm_fault_t kernfs_vma_page_mkwrite(struct vm_fault *vmf) |
414985ae | 371 | { |
11bac800 | 372 | struct file *file = vmf->vma->vm_file; |
c525aadd | 373 | struct kernfs_open_file *of = kernfs_of(file); |
9ee84466 | 374 | vm_fault_t ret; |
414985ae TH |
375 | |
376 | if (!of->vm_ops) | |
377 | return VM_FAULT_SIGBUS; | |
378 | ||
c637b8ac | 379 | if (!kernfs_get_active(of->kn)) |
414985ae TH |
380 | return VM_FAULT_SIGBUS; |
381 | ||
382 | ret = 0; | |
383 | if (of->vm_ops->page_mkwrite) | |
11bac800 | 384 | ret = of->vm_ops->page_mkwrite(vmf); |
414985ae TH |
385 | else |
386 | file_update_time(file); | |
387 | ||
c637b8ac | 388 | kernfs_put_active(of->kn); |
414985ae TH |
389 | return ret; |
390 | } | |
391 | ||
392 | static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr, | |
393 | void *buf, int len, int write) | |
394 | { | |
395 | struct file *file = vma->vm_file; | |
c525aadd | 396 | struct kernfs_open_file *of = kernfs_of(file); |
414985ae TH |
397 | int ret; |
398 | ||
399 | if (!of->vm_ops) | |
400 | return -EINVAL; | |
401 | ||
c637b8ac | 402 | if (!kernfs_get_active(of->kn)) |
414985ae TH |
403 | return -EINVAL; |
404 | ||
405 | ret = -EINVAL; | |
406 | if (of->vm_ops->access) | |
407 | ret = of->vm_ops->access(vma, addr, buf, len, write); | |
408 | ||
c637b8ac | 409 | kernfs_put_active(of->kn); |
414985ae TH |
410 | return ret; |
411 | } | |
412 | ||
413 | #ifdef CONFIG_NUMA | |
414 | static int kernfs_vma_set_policy(struct vm_area_struct *vma, | |
415 | struct mempolicy *new) | |
416 | { | |
417 | struct file *file = vma->vm_file; | |
c525aadd | 418 | struct kernfs_open_file *of = kernfs_of(file); |
414985ae TH |
419 | int ret; |
420 | ||
421 | if (!of->vm_ops) | |
422 | return 0; | |
423 | ||
c637b8ac | 424 | if (!kernfs_get_active(of->kn)) |
414985ae TH |
425 | return -EINVAL; |
426 | ||
427 | ret = 0; | |
428 | if (of->vm_ops->set_policy) | |
429 | ret = of->vm_ops->set_policy(vma, new); | |
430 | ||
c637b8ac | 431 | kernfs_put_active(of->kn); |
414985ae TH |
432 | return ret; |
433 | } | |
434 | ||
435 | static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma, | |
436 | unsigned long addr) | |
437 | { | |
438 | struct file *file = vma->vm_file; | |
c525aadd | 439 | struct kernfs_open_file *of = kernfs_of(file); |
414985ae TH |
440 | struct mempolicy *pol; |
441 | ||
442 | if (!of->vm_ops) | |
443 | return vma->vm_policy; | |
444 | ||
c637b8ac | 445 | if (!kernfs_get_active(of->kn)) |
414985ae TH |
446 | return vma->vm_policy; |
447 | ||
448 | pol = vma->vm_policy; | |
449 | if (of->vm_ops->get_policy) | |
450 | pol = of->vm_ops->get_policy(vma, addr); | |
451 | ||
c637b8ac | 452 | kernfs_put_active(of->kn); |
414985ae TH |
453 | return pol; |
454 | } | |
455 | ||
414985ae TH |
456 | #endif |
457 | ||
458 | static const struct vm_operations_struct kernfs_vm_ops = { | |
459 | .open = kernfs_vma_open, | |
460 | .fault = kernfs_vma_fault, | |
461 | .page_mkwrite = kernfs_vma_page_mkwrite, | |
462 | .access = kernfs_vma_access, | |
463 | #ifdef CONFIG_NUMA | |
464 | .set_policy = kernfs_vma_set_policy, | |
465 | .get_policy = kernfs_vma_get_policy, | |
414985ae TH |
466 | #endif |
467 | }; | |
468 | ||
c637b8ac | 469 | static int kernfs_fop_mmap(struct file *file, struct vm_area_struct *vma) |
414985ae | 470 | { |
c525aadd | 471 | struct kernfs_open_file *of = kernfs_of(file); |
414985ae TH |
472 | const struct kernfs_ops *ops; |
473 | int rc; | |
474 | ||
9b2db6e1 TH |
475 | /* |
476 | * mmap path and of->mutex are prone to triggering spurious lockdep | |
477 | * warnings and we don't want to add spurious locking dependency | |
478 | * between the two. Check whether mmap is actually implemented | |
479 | * without grabbing @of->mutex by testing HAS_MMAP flag. See the | |
480 | * comment in kernfs_file_open() for more details. | |
481 | */ | |
df23fc39 | 482 | if (!(of->kn->flags & KERNFS_HAS_MMAP)) |
9b2db6e1 TH |
483 | return -ENODEV; |
484 | ||
414985ae TH |
485 | mutex_lock(&of->mutex); |
486 | ||
487 | rc = -ENODEV; | |
c637b8ac | 488 | if (!kernfs_get_active(of->kn)) |
414985ae TH |
489 | goto out_unlock; |
490 | ||
324a56e1 | 491 | ops = kernfs_ops(of->kn); |
9b2db6e1 | 492 | rc = ops->mmap(of, vma); |
b44b2140 TH |
493 | if (rc) |
494 | goto out_put; | |
414985ae TH |
495 | |
496 | /* | |
497 | * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup() | |
498 | * to satisfy versions of X which crash if the mmap fails: that | |
499 | * substitutes a new vm_file, and we don't then want bin_vm_ops. | |
500 | */ | |
501 | if (vma->vm_file != file) | |
502 | goto out_put; | |
503 | ||
504 | rc = -EINVAL; | |
505 | if (of->mmapped && of->vm_ops != vma->vm_ops) | |
506 | goto out_put; | |
507 | ||
508 | /* | |
509 | * It is not possible to successfully wrap close. | |
510 | * So error if someone is trying to use close. | |
511 | */ | |
512 | rc = -EINVAL; | |
513 | if (vma->vm_ops && vma->vm_ops->close) | |
514 | goto out_put; | |
515 | ||
516 | rc = 0; | |
a1d82aff | 517 | of->mmapped = true; |
414985ae TH |
518 | of->vm_ops = vma->vm_ops; |
519 | vma->vm_ops = &kernfs_vm_ops; | |
520 | out_put: | |
c637b8ac | 521 | kernfs_put_active(of->kn); |
414985ae TH |
522 | out_unlock: |
523 | mutex_unlock(&of->mutex); | |
524 | ||
525 | return rc; | |
526 | } | |
527 | ||
528 | /** | |
c637b8ac | 529 | * kernfs_get_open_node - get or create kernfs_open_node |
324a56e1 | 530 | * @kn: target kernfs_node |
c525aadd | 531 | * @of: kernfs_open_file for this instance of open |
414985ae | 532 | * |
adc5e8b5 TH |
533 | * If @kn->attr.open exists, increment its reference count; otherwise, |
534 | * create one. @of is chained to the files list. | |
414985ae TH |
535 | * |
536 | * LOCKING: | |
537 | * Kernel thread context (may sleep). | |
538 | * | |
539 | * RETURNS: | |
540 | * 0 on success, -errno on failure. | |
541 | */ | |
c637b8ac TH |
542 | static int kernfs_get_open_node(struct kernfs_node *kn, |
543 | struct kernfs_open_file *of) | |
414985ae | 544 | { |
c525aadd | 545 | struct kernfs_open_node *on, *new_on = NULL; |
414985ae TH |
546 | |
547 | retry: | |
c525aadd TH |
548 | mutex_lock(&kernfs_open_file_mutex); |
549 | spin_lock_irq(&kernfs_open_node_lock); | |
414985ae | 550 | |
c525aadd TH |
551 | if (!kn->attr.open && new_on) { |
552 | kn->attr.open = new_on; | |
553 | new_on = NULL; | |
414985ae TH |
554 | } |
555 | ||
c525aadd TH |
556 | on = kn->attr.open; |
557 | if (on) { | |
558 | atomic_inc(&on->refcnt); | |
559 | list_add_tail(&of->list, &on->files); | |
414985ae TH |
560 | } |
561 | ||
c525aadd TH |
562 | spin_unlock_irq(&kernfs_open_node_lock); |
563 | mutex_unlock(&kernfs_open_file_mutex); | |
414985ae | 564 | |
c525aadd TH |
565 | if (on) { |
566 | kfree(new_on); | |
414985ae TH |
567 | return 0; |
568 | } | |
569 | ||
570 | /* not there, initialize a new one and retry */ | |
c525aadd TH |
571 | new_on = kmalloc(sizeof(*new_on), GFP_KERNEL); |
572 | if (!new_on) | |
414985ae TH |
573 | return -ENOMEM; |
574 | ||
c525aadd TH |
575 | atomic_set(&new_on->refcnt, 0); |
576 | atomic_set(&new_on->event, 1); | |
577 | init_waitqueue_head(&new_on->poll); | |
578 | INIT_LIST_HEAD(&new_on->files); | |
414985ae TH |
579 | goto retry; |
580 | } | |
581 | ||
582 | /** | |
c637b8ac | 583 | * kernfs_put_open_node - put kernfs_open_node |
324a56e1 | 584 | * @kn: target kernfs_nodet |
c525aadd | 585 | * @of: associated kernfs_open_file |
414985ae | 586 | * |
adc5e8b5 | 587 | * Put @kn->attr.open and unlink @of from the files list. If |
414985ae TH |
588 | * reference count reaches zero, disassociate and free it. |
589 | * | |
590 | * LOCKING: | |
591 | * None. | |
592 | */ | |
c637b8ac TH |
593 | static void kernfs_put_open_node(struct kernfs_node *kn, |
594 | struct kernfs_open_file *of) | |
414985ae | 595 | { |
c525aadd | 596 | struct kernfs_open_node *on = kn->attr.open; |
414985ae TH |
597 | unsigned long flags; |
598 | ||
c525aadd TH |
599 | mutex_lock(&kernfs_open_file_mutex); |
600 | spin_lock_irqsave(&kernfs_open_node_lock, flags); | |
414985ae TH |
601 | |
602 | if (of) | |
603 | list_del(&of->list); | |
604 | ||
c525aadd | 605 | if (atomic_dec_and_test(&on->refcnt)) |
adc5e8b5 | 606 | kn->attr.open = NULL; |
414985ae | 607 | else |
c525aadd | 608 | on = NULL; |
414985ae | 609 | |
c525aadd TH |
610 | spin_unlock_irqrestore(&kernfs_open_node_lock, flags); |
611 | mutex_unlock(&kernfs_open_file_mutex); | |
414985ae | 612 | |
c525aadd | 613 | kfree(on); |
414985ae TH |
614 | } |
615 | ||
c637b8ac | 616 | static int kernfs_fop_open(struct inode *inode, struct file *file) |
414985ae | 617 | { |
319ba91d | 618 | struct kernfs_node *kn = inode->i_private; |
555724a8 | 619 | struct kernfs_root *root = kernfs_root(kn); |
414985ae | 620 | const struct kernfs_ops *ops; |
c525aadd | 621 | struct kernfs_open_file *of; |
414985ae TH |
622 | bool has_read, has_write, has_mmap; |
623 | int error = -EACCES; | |
624 | ||
c637b8ac | 625 | if (!kernfs_get_active(kn)) |
414985ae TH |
626 | return -ENODEV; |
627 | ||
324a56e1 | 628 | ops = kernfs_ops(kn); |
414985ae TH |
629 | |
630 | has_read = ops->seq_show || ops->read || ops->mmap; | |
631 | has_write = ops->write || ops->mmap; | |
632 | has_mmap = ops->mmap; | |
633 | ||
555724a8 TH |
634 | /* see the flag definition for details */ |
635 | if (root->flags & KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK) { | |
636 | if ((file->f_mode & FMODE_WRITE) && | |
637 | (!(inode->i_mode & S_IWUGO) || !has_write)) | |
638 | goto err_out; | |
414985ae | 639 | |
555724a8 TH |
640 | if ((file->f_mode & FMODE_READ) && |
641 | (!(inode->i_mode & S_IRUGO) || !has_read)) | |
642 | goto err_out; | |
643 | } | |
414985ae | 644 | |
c525aadd | 645 | /* allocate a kernfs_open_file for the file */ |
414985ae | 646 | error = -ENOMEM; |
c525aadd | 647 | of = kzalloc(sizeof(struct kernfs_open_file), GFP_KERNEL); |
414985ae TH |
648 | if (!of) |
649 | goto err_out; | |
650 | ||
651 | /* | |
652 | * The following is done to give a different lockdep key to | |
653 | * @of->mutex for files which implement mmap. This is a rather | |
654 | * crude way to avoid false positive lockdep warning around | |
c1e8d7c6 | 655 | * mm->mmap_lock - mmap nests @of->mutex under mm->mmap_lock and |
414985ae | 656 | * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under |
c1e8d7c6 | 657 | * which mm->mmap_lock nests, while holding @of->mutex. As each |
414985ae TH |
658 | * open file has a separate mutex, it's okay as long as those don't |
659 | * happen on the same file. At this point, we can't easily give | |
660 | * each file a separate locking class. Let's differentiate on | |
661 | * whether the file has mmap or not for now. | |
9b2db6e1 TH |
662 | * |
663 | * Both paths of the branch look the same. They're supposed to | |
664 | * look that way and give @of->mutex different static lockdep keys. | |
414985ae TH |
665 | */ |
666 | if (has_mmap) | |
667 | mutex_init(&of->mutex); | |
668 | else | |
669 | mutex_init(&of->mutex); | |
670 | ||
324a56e1 | 671 | of->kn = kn; |
414985ae TH |
672 | of->file = file; |
673 | ||
b7ce40cf TH |
674 | /* |
675 | * Write path needs to atomic_write_len outside active reference. | |
676 | * Cache it in open_file. See kernfs_fop_write() for details. | |
677 | */ | |
678 | of->atomic_write_len = ops->atomic_write_len; | |
679 | ||
4ef67a8c N |
680 | error = -EINVAL; |
681 | /* | |
682 | * ->seq_show is incompatible with ->prealloc, | |
683 | * as seq_read does its own allocation. | |
684 | * ->read must be used instead. | |
685 | */ | |
686 | if (ops->prealloc && ops->seq_show) | |
687 | goto err_free; | |
2b75869b N |
688 | if (ops->prealloc) { |
689 | int len = of->atomic_write_len ?: PAGE_SIZE; | |
690 | of->prealloc_buf = kmalloc(len + 1, GFP_KERNEL); | |
691 | error = -ENOMEM; | |
692 | if (!of->prealloc_buf) | |
693 | goto err_free; | |
e4234a1f | 694 | mutex_init(&of->prealloc_mutex); |
2b75869b N |
695 | } |
696 | ||
414985ae TH |
697 | /* |
698 | * Always instantiate seq_file even if read access doesn't use | |
699 | * seq_file or is not requested. This unifies private data access | |
700 | * and readable regular files are the vast majority anyway. | |
701 | */ | |
702 | if (ops->seq_show) | |
703 | error = seq_open(file, &kernfs_seq_ops); | |
704 | else | |
705 | error = seq_open(file, NULL); | |
706 | if (error) | |
707 | goto err_free; | |
708 | ||
0e67db2f TH |
709 | of->seq_file = file->private_data; |
710 | of->seq_file->private = of; | |
414985ae TH |
711 | |
712 | /* seq_file clears PWRITE unconditionally, restore it if WRITE */ | |
713 | if (file->f_mode & FMODE_WRITE) | |
714 | file->f_mode |= FMODE_PWRITE; | |
715 | ||
c637b8ac TH |
716 | /* make sure we have open node struct */ |
717 | error = kernfs_get_open_node(kn, of); | |
414985ae | 718 | if (error) |
0e67db2f TH |
719 | goto err_seq_release; |
720 | ||
721 | if (ops->open) { | |
722 | /* nobody has access to @of yet, skip @of->mutex */ | |
723 | error = ops->open(of); | |
724 | if (error) | |
725 | goto err_put_node; | |
726 | } | |
414985ae TH |
727 | |
728 | /* open succeeded, put active references */ | |
c637b8ac | 729 | kernfs_put_active(kn); |
414985ae TH |
730 | return 0; |
731 | ||
0e67db2f TH |
732 | err_put_node: |
733 | kernfs_put_open_node(kn, of); | |
734 | err_seq_release: | |
414985ae TH |
735 | seq_release(inode, file); |
736 | err_free: | |
2b75869b | 737 | kfree(of->prealloc_buf); |
414985ae TH |
738 | kfree(of); |
739 | err_out: | |
c637b8ac | 740 | kernfs_put_active(kn); |
414985ae TH |
741 | return error; |
742 | } | |
743 | ||
0e67db2f TH |
744 | /* used from release/drain to ensure that ->release() is called exactly once */ |
745 | static void kernfs_release_file(struct kernfs_node *kn, | |
746 | struct kernfs_open_file *of) | |
747 | { | |
f83f3c51 TH |
748 | /* |
749 | * @of is guaranteed to have no other file operations in flight and | |
750 | * we just want to synchronize release and drain paths. | |
751 | * @kernfs_open_file_mutex is enough. @of->mutex can't be used | |
752 | * here because drain path may be called from places which can | |
753 | * cause circular dependency. | |
754 | */ | |
755 | lockdep_assert_held(&kernfs_open_file_mutex); | |
0e67db2f | 756 | |
0e67db2f TH |
757 | if (!of->released) { |
758 | /* | |
759 | * A file is never detached without being released and we | |
760 | * need to be able to release files which are deactivated | |
761 | * and being drained. Don't use kernfs_ops(). | |
762 | */ | |
763 | kn->attr.ops->release(of); | |
764 | of->released = true; | |
765 | } | |
0e67db2f TH |
766 | } |
767 | ||
c637b8ac | 768 | static int kernfs_fop_release(struct inode *inode, struct file *filp) |
414985ae | 769 | { |
319ba91d | 770 | struct kernfs_node *kn = inode->i_private; |
c525aadd | 771 | struct kernfs_open_file *of = kernfs_of(filp); |
414985ae | 772 | |
f83f3c51 TH |
773 | if (kn->flags & KERNFS_HAS_RELEASE) { |
774 | mutex_lock(&kernfs_open_file_mutex); | |
775 | kernfs_release_file(kn, of); | |
776 | mutex_unlock(&kernfs_open_file_mutex); | |
777 | } | |
778 | ||
c637b8ac | 779 | kernfs_put_open_node(kn, of); |
414985ae | 780 | seq_release(inode, filp); |
2b75869b | 781 | kfree(of->prealloc_buf); |
414985ae TH |
782 | kfree(of); |
783 | ||
784 | return 0; | |
785 | } | |
786 | ||
0e67db2f | 787 | void kernfs_drain_open_files(struct kernfs_node *kn) |
414985ae | 788 | { |
c525aadd TH |
789 | struct kernfs_open_node *on; |
790 | struct kernfs_open_file *of; | |
414985ae | 791 | |
0e67db2f | 792 | if (!(kn->flags & (KERNFS_HAS_MMAP | KERNFS_HAS_RELEASE))) |
55f6e30d GKH |
793 | return; |
794 | ||
c525aadd TH |
795 | spin_lock_irq(&kernfs_open_node_lock); |
796 | on = kn->attr.open; | |
797 | if (on) | |
798 | atomic_inc(&on->refcnt); | |
799 | spin_unlock_irq(&kernfs_open_node_lock); | |
800 | if (!on) | |
414985ae TH |
801 | return; |
802 | ||
c525aadd | 803 | mutex_lock(&kernfs_open_file_mutex); |
0e67db2f | 804 | |
c525aadd | 805 | list_for_each_entry(of, &on->files, list) { |
414985ae | 806 | struct inode *inode = file_inode(of->file); |
0e67db2f TH |
807 | |
808 | if (kn->flags & KERNFS_HAS_MMAP) | |
809 | unmap_mapping_range(inode->i_mapping, 0, 0, 1); | |
810 | ||
966fa72a VJ |
811 | if (kn->flags & KERNFS_HAS_RELEASE) |
812 | kernfs_release_file(kn, of); | |
414985ae | 813 | } |
0e67db2f | 814 | |
c525aadd | 815 | mutex_unlock(&kernfs_open_file_mutex); |
414985ae | 816 | |
c637b8ac | 817 | kernfs_put_open_node(kn, NULL); |
414985ae TH |
818 | } |
819 | ||
c637b8ac TH |
820 | /* |
821 | * Kernfs attribute files are pollable. The idea is that you read | |
414985ae TH |
822 | * the content and then you use 'poll' or 'select' to wait for |
823 | * the content to change. When the content changes (assuming the | |
824 | * manager for the kobject supports notification), poll will | |
a9a08845 | 825 | * return EPOLLERR|EPOLLPRI, and select will return the fd whether |
414985ae TH |
826 | * it is waiting for read, write, or exceptions. |
827 | * Once poll/select indicates that the value has changed, you | |
828 | * need to close and re-open the file, or seek to 0 and read again. | |
829 | * Reminder: this only works for attributes which actively support | |
830 | * it, and it is not possible to test an attribute from userspace | |
831 | * to see if it supports poll (Neither 'poll' nor 'select' return | |
832 | * an appropriate error code). When in doubt, set a suitable timeout value. | |
833 | */ | |
147e1a97 JW |
834 | __poll_t kernfs_generic_poll(struct kernfs_open_file *of, poll_table *wait) |
835 | { | |
836 | struct kernfs_node *kn = kernfs_dentry_node(of->file->f_path.dentry); | |
837 | struct kernfs_open_node *on = kn->attr.open; | |
838 | ||
839 | poll_wait(of->file, &on->poll, wait); | |
840 | ||
841 | if (of->event != atomic_read(&on->event)) | |
842 | return DEFAULT_POLLMASK|EPOLLERR|EPOLLPRI; | |
843 | ||
844 | return DEFAULT_POLLMASK; | |
845 | } | |
846 | ||
076ccb76 | 847 | static __poll_t kernfs_fop_poll(struct file *filp, poll_table *wait) |
414985ae | 848 | { |
c525aadd | 849 | struct kernfs_open_file *of = kernfs_of(filp); |
319ba91d | 850 | struct kernfs_node *kn = kernfs_dentry_node(filp->f_path.dentry); |
147e1a97 | 851 | __poll_t ret; |
414985ae | 852 | |
c637b8ac | 853 | if (!kernfs_get_active(kn)) |
147e1a97 | 854 | return DEFAULT_POLLMASK|EPOLLERR|EPOLLPRI; |
414985ae | 855 | |
147e1a97 JW |
856 | if (kn->attr.ops->poll) |
857 | ret = kn->attr.ops->poll(of, wait); | |
858 | else | |
859 | ret = kernfs_generic_poll(of, wait); | |
414985ae | 860 | |
c637b8ac | 861 | kernfs_put_active(kn); |
147e1a97 | 862 | return ret; |
414985ae TH |
863 | } |
864 | ||
ecca47ce | 865 | static void kernfs_notify_workfn(struct work_struct *work) |
414985ae | 866 | { |
ecca47ce | 867 | struct kernfs_node *kn; |
d911d987 | 868 | struct kernfs_super_info *info; |
ecca47ce TH |
869 | repeat: |
870 | /* pop one off the notify_list */ | |
871 | spin_lock_irq(&kernfs_notify_lock); | |
872 | kn = kernfs_notify_list; | |
873 | if (kn == KERNFS_NOTIFY_EOL) { | |
874 | spin_unlock_irq(&kernfs_notify_lock); | |
d911d987 | 875 | return; |
ecca47ce TH |
876 | } |
877 | kernfs_notify_list = kn->attr.notify_next; | |
878 | kn->attr.notify_next = NULL; | |
879 | spin_unlock_irq(&kernfs_notify_lock); | |
d911d987 | 880 | |
d911d987 TH |
881 | /* kick fsnotify */ |
882 | mutex_lock(&kernfs_mutex); | |
883 | ||
ecca47ce | 884 | list_for_each_entry(info, &kernfs_root(kn)->supers, node) { |
df6a58c5 | 885 | struct kernfs_node *parent; |
d911d987 | 886 | struct inode *inode; |
25b229df | 887 | struct qstr name; |
d911d987 | 888 | |
df6a58c5 TH |
889 | /* |
890 | * We want fsnotify_modify() on @kn but as the | |
891 | * modifications aren't originating from userland don't | |
892 | * have the matching @file available. Look up the inodes | |
893 | * and generate the events manually. | |
894 | */ | |
67c0496e | 895 | inode = ilookup(info->sb, kernfs_ino(kn)); |
d911d987 TH |
896 | if (!inode) |
897 | continue; | |
898 | ||
25b229df | 899 | name = (struct qstr)QSTR_INIT(kn->name, strlen(kn->name)); |
df6a58c5 TH |
900 | parent = kernfs_get_parent(kn); |
901 | if (parent) { | |
902 | struct inode *p_inode; | |
903 | ||
67c0496e | 904 | p_inode = ilookup(info->sb, kernfs_ino(parent)); |
df6a58c5 TH |
905 | if (p_inode) { |
906 | fsnotify(p_inode, FS_MODIFY | FS_EVENT_ON_CHILD, | |
25b229df | 907 | inode, FSNOTIFY_EVENT_INODE, &name, 0); |
df6a58c5 TH |
908 | iput(p_inode); |
909 | } | |
910 | ||
911 | kernfs_put(parent); | |
d911d987 TH |
912 | } |
913 | ||
df6a58c5 | 914 | fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE, |
25b229df | 915 | &name, 0); |
d911d987 TH |
916 | iput(inode); |
917 | } | |
918 | ||
919 | mutex_unlock(&kernfs_mutex); | |
ecca47ce TH |
920 | kernfs_put(kn); |
921 | goto repeat; | |
922 | } | |
923 | ||
924 | /** | |
925 | * kernfs_notify - notify a kernfs file | |
926 | * @kn: file to notify | |
927 | * | |
928 | * Notify @kn such that poll(2) on @kn wakes up. Maybe be called from any | |
929 | * context. | |
930 | */ | |
931 | void kernfs_notify(struct kernfs_node *kn) | |
932 | { | |
933 | static DECLARE_WORK(kernfs_notify_work, kernfs_notify_workfn); | |
934 | unsigned long flags; | |
03c0a920 | 935 | struct kernfs_open_node *on; |
ecca47ce TH |
936 | |
937 | if (WARN_ON(kernfs_type(kn) != KERNFS_FILE)) | |
938 | return; | |
939 | ||
03c0a920 RR |
940 | /* kick poll immediately */ |
941 | spin_lock_irqsave(&kernfs_open_node_lock, flags); | |
942 | on = kn->attr.open; | |
943 | if (on) { | |
944 | atomic_inc(&on->event); | |
945 | wake_up_interruptible(&on->poll); | |
946 | } | |
947 | spin_unlock_irqrestore(&kernfs_open_node_lock, flags); | |
948 | ||
949 | /* schedule work to kick fsnotify */ | |
ecca47ce TH |
950 | spin_lock_irqsave(&kernfs_notify_lock, flags); |
951 | if (!kn->attr.notify_next) { | |
952 | kernfs_get(kn); | |
953 | kn->attr.notify_next = kernfs_notify_list; | |
954 | kernfs_notify_list = kn; | |
955 | schedule_work(&kernfs_notify_work); | |
956 | } | |
957 | spin_unlock_irqrestore(&kernfs_notify_lock, flags); | |
414985ae TH |
958 | } |
959 | EXPORT_SYMBOL_GPL(kernfs_notify); | |
960 | ||
a797bfc3 | 961 | const struct file_operations kernfs_file_fops = { |
c637b8ac TH |
962 | .read = kernfs_fop_read, |
963 | .write = kernfs_fop_write, | |
414985ae | 964 | .llseek = generic_file_llseek, |
c637b8ac TH |
965 | .mmap = kernfs_fop_mmap, |
966 | .open = kernfs_fop_open, | |
967 | .release = kernfs_fop_release, | |
968 | .poll = kernfs_fop_poll, | |
2a9becdd | 969 | .fsync = noop_fsync, |
414985ae TH |
970 | }; |
971 | ||
972 | /** | |
2063d608 | 973 | * __kernfs_create_file - kernfs internal function to create a file |
414985ae TH |
974 | * @parent: directory to create the file in |
975 | * @name: name of the file | |
976 | * @mode: mode of the file | |
488dee96 DT |
977 | * @uid: uid of the file |
978 | * @gid: gid of the file | |
414985ae TH |
979 | * @size: size of the file |
980 | * @ops: kernfs operations for the file | |
981 | * @priv: private data for the file | |
982 | * @ns: optional namespace tag of the file | |
983 | * @key: lockdep key for the file's active_ref, %NULL to disable lockdep | |
984 | * | |
985 | * Returns the created node on success, ERR_PTR() value on error. | |
986 | */ | |
2063d608 TH |
987 | struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent, |
988 | const char *name, | |
488dee96 DT |
989 | umode_t mode, kuid_t uid, kgid_t gid, |
990 | loff_t size, | |
2063d608 TH |
991 | const struct kernfs_ops *ops, |
992 | void *priv, const void *ns, | |
2063d608 | 993 | struct lock_class_key *key) |
414985ae | 994 | { |
324a56e1 | 995 | struct kernfs_node *kn; |
2063d608 | 996 | unsigned flags; |
414985ae TH |
997 | int rc; |
998 | ||
2063d608 | 999 | flags = KERNFS_FILE; |
2063d608 | 1000 | |
488dee96 DT |
1001 | kn = kernfs_new_node(parent, name, (mode & S_IALLUGO) | S_IFREG, |
1002 | uid, gid, flags); | |
324a56e1 | 1003 | if (!kn) |
414985ae TH |
1004 | return ERR_PTR(-ENOMEM); |
1005 | ||
adc5e8b5 TH |
1006 | kn->attr.ops = ops; |
1007 | kn->attr.size = size; | |
1008 | kn->ns = ns; | |
324a56e1 | 1009 | kn->priv = priv; |
414985ae TH |
1010 | |
1011 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
1012 | if (key) { | |
0f605db5 | 1013 | lockdep_init_map(&kn->dep_map, "kn->active", key, 0); |
df23fc39 | 1014 | kn->flags |= KERNFS_LOCKDEP; |
414985ae TH |
1015 | } |
1016 | #endif | |
1017 | ||
1018 | /* | |
adc5e8b5 | 1019 | * kn->attr.ops is accesible only while holding active ref. We |
414985ae TH |
1020 | * need to know whether some ops are implemented outside active |
1021 | * ref. Cache their existence in flags. | |
1022 | */ | |
1023 | if (ops->seq_show) | |
df23fc39 | 1024 | kn->flags |= KERNFS_HAS_SEQ_SHOW; |
414985ae | 1025 | if (ops->mmap) |
df23fc39 | 1026 | kn->flags |= KERNFS_HAS_MMAP; |
0e67db2f TH |
1027 | if (ops->release) |
1028 | kn->flags |= KERNFS_HAS_RELEASE; | |
414985ae | 1029 | |
988cd7af | 1030 | rc = kernfs_add_one(kn); |
414985ae | 1031 | if (rc) { |
324a56e1 | 1032 | kernfs_put(kn); |
414985ae TH |
1033 | return ERR_PTR(rc); |
1034 | } | |
324a56e1 | 1035 | return kn; |
414985ae | 1036 | } |