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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Framework for buffer objects that can be shared across devices/subsystems.
4 *
5 * Copyright(C) 2011 Linaro Limited. All rights reserved.
6 * Author: Sumit Semwal <sumit.semwal@ti.com>
7 *
8 * Many thanks to linaro-mm-sig list, and specially
9 * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
10 * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
11 * refining of this idea.
12 */
13
14#include <linux/fs.h>
15#include <linux/slab.h>
16#include <linux/dma-buf.h>
17#include <linux/dma-fence.h>
18#include <linux/anon_inodes.h>
19#include <linux/export.h>
20#include <linux/debugfs.h>
21#include <linux/module.h>
22#include <linux/seq_file.h>
23#include <linux/poll.h>
24#include <linux/dma-resv.h>
25#include <linux/mm.h>
26#include <linux/mount.h>
27#include <linux/pseudo_fs.h>
28
29#include <uapi/linux/dma-buf.h>
30#include <uapi/linux/magic.h>
31
32static inline int is_dma_buf_file(struct file *);
33
34struct dma_buf_list {
35 struct list_head head;
36 struct mutex lock;
37};
38
39static struct dma_buf_list db_list;
40
41static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
42{
43 struct dma_buf *dmabuf;
44 char name[DMA_BUF_NAME_LEN];
45 size_t ret = 0;
46
47 dmabuf = dentry->d_fsdata;
48 spin_lock(&dmabuf->name_lock);
49 if (dmabuf->name)
50 ret = strlcpy(name, dmabuf->name, DMA_BUF_NAME_LEN);
51 spin_unlock(&dmabuf->name_lock);
52
53 return dynamic_dname(dentry, buffer, buflen, "/%s:%s",
54 dentry->d_name.name, ret > 0 ? name : "");
55}
56
57static void dma_buf_release(struct dentry *dentry)
58{
59 struct dma_buf *dmabuf;
60
61 dmabuf = dentry->d_fsdata;
62 if (unlikely(!dmabuf))
63 return;
64
65 BUG_ON(dmabuf->vmapping_counter);
66
67 /*
68 * Any fences that a dma-buf poll can wait on should be signaled
69 * before releasing dma-buf. This is the responsibility of each
70 * driver that uses the reservation objects.
71 *
72 * If you hit this BUG() it means someone dropped their ref to the
73 * dma-buf while still having pending operation to the buffer.
74 */
75 BUG_ON(dmabuf->cb_shared.active || dmabuf->cb_excl.active);
76
77 dmabuf->ops->release(dmabuf);
78
79 mutex_lock(&db_list.lock);
80 list_del(&dmabuf->list_node);
81 mutex_unlock(&db_list.lock);
82
83 if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
84 dma_resv_fini(dmabuf->resv);
85
86 module_put(dmabuf->owner);
87 kfree(dmabuf->name);
88 kfree(dmabuf);
89}
90
91static const struct dentry_operations dma_buf_dentry_ops = {
92 .d_dname = dmabuffs_dname,
93 .d_release = dma_buf_release,
94};
95
96static struct vfsmount *dma_buf_mnt;
97
98static int dma_buf_fs_init_context(struct fs_context *fc)
99{
100 struct pseudo_fs_context *ctx;
101
102 ctx = init_pseudo(fc, DMA_BUF_MAGIC);
103 if (!ctx)
104 return -ENOMEM;
105 ctx->dops = &dma_buf_dentry_ops;
106 return 0;
107}
108
109static struct file_system_type dma_buf_fs_type = {
110 .name = "dmabuf",
111 .init_fs_context = dma_buf_fs_init_context,
112 .kill_sb = kill_anon_super,
113};
114
115static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
116{
117 struct dma_buf *dmabuf;
118
119 if (!is_dma_buf_file(file))
120 return -EINVAL;
121
122 dmabuf = file->private_data;
123
124 /* check if buffer supports mmap */
125 if (!dmabuf->ops->mmap)
126 return -EINVAL;
127
128 /* check for overflowing the buffer's size */
129 if (vma->vm_pgoff + vma_pages(vma) >
130 dmabuf->size >> PAGE_SHIFT)
131 return -EINVAL;
132
133 return dmabuf->ops->mmap(dmabuf, vma);
134}
135
136static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
137{
138 struct dma_buf *dmabuf;
139 loff_t base;
140
141 if (!is_dma_buf_file(file))
142 return -EBADF;
143
144 dmabuf = file->private_data;
145
146 /* only support discovering the end of the buffer,
147 but also allow SEEK_SET to maintain the idiomatic
148 SEEK_END(0), SEEK_CUR(0) pattern */
149 if (whence == SEEK_END)
150 base = dmabuf->size;
151 else if (whence == SEEK_SET)
152 base = 0;
153 else
154 return -EINVAL;
155
156 if (offset != 0)
157 return -EINVAL;
158
159 return base + offset;
160}
161
162/**
163 * DOC: implicit fence polling
164 *
165 * To support cross-device and cross-driver synchronization of buffer access
166 * implicit fences (represented internally in the kernel with &struct dma_fence)
167 * can be attached to a &dma_buf. The glue for that and a few related things are
168 * provided in the &dma_resv structure.
169 *
170 * Userspace can query the state of these implicitly tracked fences using poll()
171 * and related system calls:
172 *
173 * - Checking for EPOLLIN, i.e. read access, can be use to query the state of the
174 * most recent write or exclusive fence.
175 *
176 * - Checking for EPOLLOUT, i.e. write access, can be used to query the state of
177 * all attached fences, shared and exclusive ones.
178 *
179 * Note that this only signals the completion of the respective fences, i.e. the
180 * DMA transfers are complete. Cache flushing and any other necessary
181 * preparations before CPU access can begin still need to happen.
182 */
183
184static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
185{
186 struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;
187 unsigned long flags;
188
189 spin_lock_irqsave(&dcb->poll->lock, flags);
190 wake_up_locked_poll(dcb->poll, dcb->active);
191 dcb->active = 0;
192 spin_unlock_irqrestore(&dcb->poll->lock, flags);
193}
194
195static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
196{
197 struct dma_buf *dmabuf;
198 struct dma_resv *resv;
199 struct dma_resv_list *fobj;
200 struct dma_fence *fence_excl;
201 __poll_t events;
202 unsigned shared_count, seq;
203
204 dmabuf = file->private_data;
205 if (!dmabuf || !dmabuf->resv)
206 return EPOLLERR;
207
208 resv = dmabuf->resv;
209
210 poll_wait(file, &dmabuf->poll, poll);
211
212 events = poll_requested_events(poll) & (EPOLLIN | EPOLLOUT);
213 if (!events)
214 return 0;
215
216retry:
217 seq = read_seqcount_begin(&resv->seq);
218 rcu_read_lock();
219
220 fobj = rcu_dereference(resv->fence);
221 if (fobj)
222 shared_count = fobj->shared_count;
223 else
224 shared_count = 0;
225 fence_excl = rcu_dereference(resv->fence_excl);
226 if (read_seqcount_retry(&resv->seq, seq)) {
227 rcu_read_unlock();
228 goto retry;
229 }
230
231 if (fence_excl && (!(events & EPOLLOUT) || shared_count == 0)) {
232 struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_excl;
233 __poll_t pevents = EPOLLIN;
234
235 if (shared_count == 0)
236 pevents |= EPOLLOUT;
237
238 spin_lock_irq(&dmabuf->poll.lock);
239 if (dcb->active) {
240 dcb->active |= pevents;
241 events &= ~pevents;
242 } else
243 dcb->active = pevents;
244 spin_unlock_irq(&dmabuf->poll.lock);
245
246 if (events & pevents) {
247 if (!dma_fence_get_rcu(fence_excl)) {
248 /* force a recheck */
249 events &= ~pevents;
250 dma_buf_poll_cb(NULL, &dcb->cb);
251 } else if (!dma_fence_add_callback(fence_excl, &dcb->cb,
252 dma_buf_poll_cb)) {
253 events &= ~pevents;
254 dma_fence_put(fence_excl);
255 } else {
256 /*
257 * No callback queued, wake up any additional
258 * waiters.
259 */
260 dma_fence_put(fence_excl);
261 dma_buf_poll_cb(NULL, &dcb->cb);
262 }
263 }
264 }
265
266 if ((events & EPOLLOUT) && shared_count > 0) {
267 struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_shared;
268 int i;
269
270 /* Only queue a new callback if no event has fired yet */
271 spin_lock_irq(&dmabuf->poll.lock);
272 if (dcb->active)
273 events &= ~EPOLLOUT;
274 else
275 dcb->active = EPOLLOUT;
276 spin_unlock_irq(&dmabuf->poll.lock);
277
278 if (!(events & EPOLLOUT))
279 goto out;
280
281 for (i = 0; i < shared_count; ++i) {
282 struct dma_fence *fence = rcu_dereference(fobj->shared[i]);
283
284 if (!dma_fence_get_rcu(fence)) {
285 /*
286 * fence refcount dropped to zero, this means
287 * that fobj has been freed
288 *
289 * call dma_buf_poll_cb and force a recheck!
290 */
291 events &= ~EPOLLOUT;
292 dma_buf_poll_cb(NULL, &dcb->cb);
293 break;
294 }
295 if (!dma_fence_add_callback(fence, &dcb->cb,
296 dma_buf_poll_cb)) {
297 dma_fence_put(fence);
298 events &= ~EPOLLOUT;
299 break;
300 }
301 dma_fence_put(fence);
302 }
303
304 /* No callback queued, wake up any additional waiters. */
305 if (i == shared_count)
306 dma_buf_poll_cb(NULL, &dcb->cb);
307 }
308
309out:
310 rcu_read_unlock();
311 return events;
312}
313
314/**
315 * dma_buf_set_name - Set a name to a specific dma_buf to track the usage.
316 * The name of the dma-buf buffer can only be set when the dma-buf is not
317 * attached to any devices. It could theoritically support changing the
318 * name of the dma-buf if the same piece of memory is used for multiple
319 * purpose between different devices.
320 *
321 * @dmabuf: [in] dmabuf buffer that will be renamed.
322 * @buf: [in] A piece of userspace memory that contains the name of
323 * the dma-buf.
324 *
325 * Returns 0 on success. If the dma-buf buffer is already attached to
326 * devices, return -EBUSY.
327 *
328 */
329static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
330{
331 char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
332 long ret = 0;
333
334 if (IS_ERR(name))
335 return PTR_ERR(name);
336
337 dma_resv_lock(dmabuf->resv, NULL);
338 if (!list_empty(&dmabuf->attachments)) {
339 ret = -EBUSY;
340 kfree(name);
341 goto out_unlock;
342 }
343 spin_lock(&dmabuf->name_lock);
344 kfree(dmabuf->name);
345 dmabuf->name = name;
346 spin_unlock(&dmabuf->name_lock);
347
348out_unlock:
349 dma_resv_unlock(dmabuf->resv);
350 return ret;
351}
352
353static long dma_buf_ioctl(struct file *file,
354 unsigned int cmd, unsigned long arg)
355{
356 struct dma_buf *dmabuf;
357 struct dma_buf_sync sync;
358 enum dma_data_direction direction;
359 int ret;
360
361 dmabuf = file->private_data;
362
363 switch (cmd) {
364 case DMA_BUF_IOCTL_SYNC:
365 if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
366 return -EFAULT;
367
368 if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
369 return -EINVAL;
370
371 switch (sync.flags & DMA_BUF_SYNC_RW) {
372 case DMA_BUF_SYNC_READ:
373 direction = DMA_FROM_DEVICE;
374 break;
375 case DMA_BUF_SYNC_WRITE:
376 direction = DMA_TO_DEVICE;
377 break;
378 case DMA_BUF_SYNC_RW:
379 direction = DMA_BIDIRECTIONAL;
380 break;
381 default:
382 return -EINVAL;
383 }
384
385 if (sync.flags & DMA_BUF_SYNC_END)
386 ret = dma_buf_end_cpu_access(dmabuf, direction);
387 else
388 ret = dma_buf_begin_cpu_access(dmabuf, direction);
389
390 return ret;
391
392 case DMA_BUF_SET_NAME_A:
393 case DMA_BUF_SET_NAME_B:
394 return dma_buf_set_name(dmabuf, (const char __user *)arg);
395
396 default:
397 return -ENOTTY;
398 }
399}
400
401static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file)
402{
403 struct dma_buf *dmabuf = file->private_data;
404
405 seq_printf(m, "size:\t%zu\n", dmabuf->size);
406 /* Don't count the temporary reference taken inside procfs seq_show */
407 seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1);
408 seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name);
409 spin_lock(&dmabuf->name_lock);
410 if (dmabuf->name)
411 seq_printf(m, "name:\t%s\n", dmabuf->name);
412 spin_unlock(&dmabuf->name_lock);
413}
414
415static const struct file_operations dma_buf_fops = {
416 .mmap = dma_buf_mmap_internal,
417 .llseek = dma_buf_llseek,
418 .poll = dma_buf_poll,
419 .unlocked_ioctl = dma_buf_ioctl,
420 .compat_ioctl = compat_ptr_ioctl,
421 .show_fdinfo = dma_buf_show_fdinfo,
422};
423
424/*
425 * is_dma_buf_file - Check if struct file* is associated with dma_buf
426 */
427static inline int is_dma_buf_file(struct file *file)
428{
429 return file->f_op == &dma_buf_fops;
430}
431
432static struct file *dma_buf_getfile(struct dma_buf *dmabuf, int flags)
433{
434 struct file *file;
435 struct inode *inode = alloc_anon_inode(dma_buf_mnt->mnt_sb);
436
437 if (IS_ERR(inode))
438 return ERR_CAST(inode);
439
440 inode->i_size = dmabuf->size;
441 inode_set_bytes(inode, dmabuf->size);
442
443 file = alloc_file_pseudo(inode, dma_buf_mnt, "dmabuf",
444 flags, &dma_buf_fops);
445 if (IS_ERR(file))
446 goto err_alloc_file;
447 file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
448 file->private_data = dmabuf;
449 file->f_path.dentry->d_fsdata = dmabuf;
450
451 return file;
452
453err_alloc_file:
454 iput(inode);
455 return file;
456}
457
458/**
459 * DOC: dma buf device access
460 *
461 * For device DMA access to a shared DMA buffer the usual sequence of operations
462 * is fairly simple:
463 *
464 * 1. The exporter defines his exporter instance using
465 * DEFINE_DMA_BUF_EXPORT_INFO() and calls dma_buf_export() to wrap a private
466 * buffer object into a &dma_buf. It then exports that &dma_buf to userspace
467 * as a file descriptor by calling dma_buf_fd().
468 *
469 * 2. Userspace passes this file-descriptors to all drivers it wants this buffer
470 * to share with: First the filedescriptor is converted to a &dma_buf using
471 * dma_buf_get(). Then the buffer is attached to the device using
472 * dma_buf_attach().
473 *
474 * Up to this stage the exporter is still free to migrate or reallocate the
475 * backing storage.
476 *
477 * 3. Once the buffer is attached to all devices userspace can initiate DMA
478 * access to the shared buffer. In the kernel this is done by calling
479 * dma_buf_map_attachment() and dma_buf_unmap_attachment().
480 *
481 * 4. Once a driver is done with a shared buffer it needs to call
482 * dma_buf_detach() (after cleaning up any mappings) and then release the
483 * reference acquired with dma_buf_get by calling dma_buf_put().
484 *
485 * For the detailed semantics exporters are expected to implement see
486 * &dma_buf_ops.
487 */
488
489/**
490 * dma_buf_export - Creates a new dma_buf, and associates an anon file
491 * with this buffer, so it can be exported.
492 * Also connect the allocator specific data and ops to the buffer.
493 * Additionally, provide a name string for exporter; useful in debugging.
494 *
495 * @exp_info: [in] holds all the export related information provided
496 * by the exporter. see &struct dma_buf_export_info
497 * for further details.
498 *
499 * Returns, on success, a newly created dma_buf object, which wraps the
500 * supplied private data and operations for dma_buf_ops. On either missing
501 * ops, or error in allocating struct dma_buf, will return negative error.
502 *
503 * For most cases the easiest way to create @exp_info is through the
504 * %DEFINE_DMA_BUF_EXPORT_INFO macro.
505 */
506struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
507{
508 struct dma_buf *dmabuf;
509 struct dma_resv *resv = exp_info->resv;
510 struct file *file;
511 size_t alloc_size = sizeof(struct dma_buf);
512 int ret;
513
514 if (!exp_info->resv)
515 alloc_size += sizeof(struct dma_resv);
516 else
517 /* prevent &dma_buf[1] == dma_buf->resv */
518 alloc_size += 1;
519
520 if (WARN_ON(!exp_info->priv
521 || !exp_info->ops
522 || !exp_info->ops->map_dma_buf
523 || !exp_info->ops->unmap_dma_buf
524 || !exp_info->ops->release)) {
525 return ERR_PTR(-EINVAL);
526 }
527
528 if (WARN_ON(exp_info->ops->cache_sgt_mapping &&
529 (exp_info->ops->pin || exp_info->ops->unpin)))
530 return ERR_PTR(-EINVAL);
531
532 if (WARN_ON(!exp_info->ops->pin != !exp_info->ops->unpin))
533 return ERR_PTR(-EINVAL);
534
535 if (!try_module_get(exp_info->owner))
536 return ERR_PTR(-ENOENT);
537
538 dmabuf = kzalloc(alloc_size, GFP_KERNEL);
539 if (!dmabuf) {
540 ret = -ENOMEM;
541 goto err_module;
542 }
543
544 dmabuf->priv = exp_info->priv;
545 dmabuf->ops = exp_info->ops;
546 dmabuf->size = exp_info->size;
547 dmabuf->exp_name = exp_info->exp_name;
548 dmabuf->owner = exp_info->owner;
549 spin_lock_init(&dmabuf->name_lock);
550 init_waitqueue_head(&dmabuf->poll);
551 dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll;
552 dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0;
553
554 if (!resv) {
555 resv = (struct dma_resv *)&dmabuf[1];
556 dma_resv_init(resv);
557 }
558 dmabuf->resv = resv;
559
560 file = dma_buf_getfile(dmabuf, exp_info->flags);
561 if (IS_ERR(file)) {
562 ret = PTR_ERR(file);
563 goto err_dmabuf;
564 }
565
566 file->f_mode |= FMODE_LSEEK;
567 dmabuf->file = file;
568
569 mutex_init(&dmabuf->lock);
570 INIT_LIST_HEAD(&dmabuf->attachments);
571
572 mutex_lock(&db_list.lock);
573 list_add(&dmabuf->list_node, &db_list.head);
574 mutex_unlock(&db_list.lock);
575
576 return dmabuf;
577
578err_dmabuf:
579 kfree(dmabuf);
580err_module:
581 module_put(exp_info->owner);
582 return ERR_PTR(ret);
583}
584EXPORT_SYMBOL_GPL(dma_buf_export);
585
586/**
587 * dma_buf_fd - returns a file descriptor for the given dma_buf
588 * @dmabuf: [in] pointer to dma_buf for which fd is required.
589 * @flags: [in] flags to give to fd
590 *
591 * On success, returns an associated 'fd'. Else, returns error.
592 */
593int dma_buf_fd(struct dma_buf *dmabuf, int flags)
594{
595 int fd;
596
597 if (!dmabuf || !dmabuf->file)
598 return -EINVAL;
599
600 fd = get_unused_fd_flags(flags);
601 if (fd < 0)
602 return fd;
603
604 fd_install(fd, dmabuf->file);
605
606 return fd;
607}
608EXPORT_SYMBOL_GPL(dma_buf_fd);
609
610/**
611 * dma_buf_get - returns the dma_buf structure related to an fd
612 * @fd: [in] fd associated with the dma_buf to be returned
613 *
614 * On success, returns the dma_buf structure associated with an fd; uses
615 * file's refcounting done by fget to increase refcount. returns ERR_PTR
616 * otherwise.
617 */
618struct dma_buf *dma_buf_get(int fd)
619{
620 struct file *file;
621
622 file = fget(fd);
623
624 if (!file)
625 return ERR_PTR(-EBADF);
626
627 if (!is_dma_buf_file(file)) {
628 fput(file);
629 return ERR_PTR(-EINVAL);
630 }
631
632 return file->private_data;
633}
634EXPORT_SYMBOL_GPL(dma_buf_get);
635
636/**
637 * dma_buf_put - decreases refcount of the buffer
638 * @dmabuf: [in] buffer to reduce refcount of
639 *
640 * Uses file's refcounting done implicitly by fput().
641 *
642 * If, as a result of this call, the refcount becomes 0, the 'release' file
643 * operation related to this fd is called. It calls &dma_buf_ops.release vfunc
644 * in turn, and frees the memory allocated for dmabuf when exported.
645 */
646void dma_buf_put(struct dma_buf *dmabuf)
647{
648 if (WARN_ON(!dmabuf || !dmabuf->file))
649 return;
650
651 fput(dmabuf->file);
652}
653EXPORT_SYMBOL_GPL(dma_buf_put);
654
655/**
656 * dma_buf_dynamic_attach - Add the device to dma_buf's attachments list; optionally,
657 * calls attach() of dma_buf_ops to allow device-specific attach functionality
658 * @dmabuf: [in] buffer to attach device to.
659 * @dev: [in] device to be attached.
660 * @importer_ops: [in] importer operations for the attachment
661 * @importer_priv: [in] importer private pointer for the attachment
662 *
663 * Returns struct dma_buf_attachment pointer for this attachment. Attachments
664 * must be cleaned up by calling dma_buf_detach().
665 *
666 * Returns:
667 *
668 * A pointer to newly created &dma_buf_attachment on success, or a negative
669 * error code wrapped into a pointer on failure.
670 *
671 * Note that this can fail if the backing storage of @dmabuf is in a place not
672 * accessible to @dev, and cannot be moved to a more suitable place. This is
673 * indicated with the error code -EBUSY.
674 */
675struct dma_buf_attachment *
676dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
677 const struct dma_buf_attach_ops *importer_ops,
678 void *importer_priv)
679{
680 struct dma_buf_attachment *attach;
681 int ret;
682
683 if (WARN_ON(!dmabuf || !dev))
684 return ERR_PTR(-EINVAL);
685
686 if (WARN_ON(importer_ops && !importer_ops->move_notify))
687 return ERR_PTR(-EINVAL);
688
689 attach = kzalloc(sizeof(*attach), GFP_KERNEL);
690 if (!attach)
691 return ERR_PTR(-ENOMEM);
692
693 attach->dev = dev;
694 attach->dmabuf = dmabuf;
695 if (importer_ops)
696 attach->peer2peer = importer_ops->allow_peer2peer;
697 attach->importer_ops = importer_ops;
698 attach->importer_priv = importer_priv;
699
700 if (dmabuf->ops->attach) {
701 ret = dmabuf->ops->attach(dmabuf, attach);
702 if (ret)
703 goto err_attach;
704 }
705 dma_resv_lock(dmabuf->resv, NULL);
706 list_add(&attach->node, &dmabuf->attachments);
707 dma_resv_unlock(dmabuf->resv);
708
709 /* When either the importer or the exporter can't handle dynamic
710 * mappings we cache the mapping here to avoid issues with the
711 * reservation object lock.
712 */
713 if (dma_buf_attachment_is_dynamic(attach) !=
714 dma_buf_is_dynamic(dmabuf)) {
715 struct sg_table *sgt;
716
717 if (dma_buf_is_dynamic(attach->dmabuf)) {
718 dma_resv_lock(attach->dmabuf->resv, NULL);
719 ret = dma_buf_pin(attach);
720 if (ret)
721 goto err_unlock;
722 }
723
724 sgt = dmabuf->ops->map_dma_buf(attach, DMA_BIDIRECTIONAL);
725 if (!sgt)
726 sgt = ERR_PTR(-ENOMEM);
727 if (IS_ERR(sgt)) {
728 ret = PTR_ERR(sgt);
729 goto err_unpin;
730 }
731 if (dma_buf_is_dynamic(attach->dmabuf))
732 dma_resv_unlock(attach->dmabuf->resv);
733 attach->sgt = sgt;
734 attach->dir = DMA_BIDIRECTIONAL;
735 }
736
737 return attach;
738
739err_attach:
740 kfree(attach);
741 return ERR_PTR(ret);
742
743err_unpin:
744 if (dma_buf_is_dynamic(attach->dmabuf))
745 dma_buf_unpin(attach);
746
747err_unlock:
748 if (dma_buf_is_dynamic(attach->dmabuf))
749 dma_resv_unlock(attach->dmabuf->resv);
750
751 dma_buf_detach(dmabuf, attach);
752 return ERR_PTR(ret);
753}
754EXPORT_SYMBOL_GPL(dma_buf_dynamic_attach);
755
756/**
757 * dma_buf_attach - Wrapper for dma_buf_dynamic_attach
758 * @dmabuf: [in] buffer to attach device to.
759 * @dev: [in] device to be attached.
760 *
761 * Wrapper to call dma_buf_dynamic_attach() for drivers which still use a static
762 * mapping.
763 */
764struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
765 struct device *dev)
766{
767 return dma_buf_dynamic_attach(dmabuf, dev, NULL, NULL);
768}
769EXPORT_SYMBOL_GPL(dma_buf_attach);
770
771/**
772 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
773 * optionally calls detach() of dma_buf_ops for device-specific detach
774 * @dmabuf: [in] buffer to detach from.
775 * @attach: [in] attachment to be detached; is free'd after this call.
776 *
777 * Clean up a device attachment obtained by calling dma_buf_attach().
778 */
779void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
780{
781 if (WARN_ON(!dmabuf || !attach))
782 return;
783
784 if (attach->sgt) {
785 if (dma_buf_is_dynamic(attach->dmabuf))
786 dma_resv_lock(attach->dmabuf->resv, NULL);
787
788 dmabuf->ops->unmap_dma_buf(attach, attach->sgt, attach->dir);
789
790 if (dma_buf_is_dynamic(attach->dmabuf)) {
791 dma_buf_unpin(attach);
792 dma_resv_unlock(attach->dmabuf->resv);
793 }
794 }
795
796 dma_resv_lock(dmabuf->resv, NULL);
797 list_del(&attach->node);
798 dma_resv_unlock(dmabuf->resv);
799 if (dmabuf->ops->detach)
800 dmabuf->ops->detach(dmabuf, attach);
801
802 kfree(attach);
803}
804EXPORT_SYMBOL_GPL(dma_buf_detach);
805
806/**
807 * dma_buf_pin - Lock down the DMA-buf
808 *
809 * @attach: [in] attachment which should be pinned
810 *
811 * Returns:
812 * 0 on success, negative error code on failure.
813 */
814int dma_buf_pin(struct dma_buf_attachment *attach)
815{
816 struct dma_buf *dmabuf = attach->dmabuf;
817 int ret = 0;
818
819 dma_resv_assert_held(dmabuf->resv);
820
821 if (dmabuf->ops->pin)
822 ret = dmabuf->ops->pin(attach);
823
824 return ret;
825}
826EXPORT_SYMBOL_GPL(dma_buf_pin);
827
828/**
829 * dma_buf_unpin - Remove lock from DMA-buf
830 *
831 * @attach: [in] attachment which should be unpinned
832 */
833void dma_buf_unpin(struct dma_buf_attachment *attach)
834{
835 struct dma_buf *dmabuf = attach->dmabuf;
836
837 dma_resv_assert_held(dmabuf->resv);
838
839 if (dmabuf->ops->unpin)
840 dmabuf->ops->unpin(attach);
841}
842EXPORT_SYMBOL_GPL(dma_buf_unpin);
843
844/**
845 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
846 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
847 * dma_buf_ops.
848 * @attach: [in] attachment whose scatterlist is to be returned
849 * @direction: [in] direction of DMA transfer
850 *
851 * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
852 * on error. May return -EINTR if it is interrupted by a signal.
853 *
854 * A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that
855 * the underlying backing storage is pinned for as long as a mapping exists,
856 * therefore users/importers should not hold onto a mapping for undue amounts of
857 * time.
858 */
859struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
860 enum dma_data_direction direction)
861{
862 struct sg_table *sg_table;
863 int r;
864
865 might_sleep();
866
867 if (WARN_ON(!attach || !attach->dmabuf))
868 return ERR_PTR(-EINVAL);
869
870 if (dma_buf_attachment_is_dynamic(attach))
871 dma_resv_assert_held(attach->dmabuf->resv);
872
873 if (attach->sgt) {
874 /*
875 * Two mappings with different directions for the same
876 * attachment are not allowed.
877 */
878 if (attach->dir != direction &&
879 attach->dir != DMA_BIDIRECTIONAL)
880 return ERR_PTR(-EBUSY);
881
882 return attach->sgt;
883 }
884
885 if (dma_buf_is_dynamic(attach->dmabuf)) {
886 dma_resv_assert_held(attach->dmabuf->resv);
887 if (!IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY)) {
888 r = dma_buf_pin(attach);
889 if (r)
890 return ERR_PTR(r);
891 }
892 }
893
894 sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
895 if (!sg_table)
896 sg_table = ERR_PTR(-ENOMEM);
897
898 if (IS_ERR(sg_table) && dma_buf_is_dynamic(attach->dmabuf) &&
899 !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
900 dma_buf_unpin(attach);
901
902 if (!IS_ERR(sg_table) && attach->dmabuf->ops->cache_sgt_mapping) {
903 attach->sgt = sg_table;
904 attach->dir = direction;
905 }
906
907 return sg_table;
908}
909EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
910
911/**
912 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
913 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
914 * dma_buf_ops.
915 * @attach: [in] attachment to unmap buffer from
916 * @sg_table: [in] scatterlist info of the buffer to unmap
917 * @direction: [in] direction of DMA transfer
918 *
919 * This unmaps a DMA mapping for @attached obtained by dma_buf_map_attachment().
920 */
921void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
922 struct sg_table *sg_table,
923 enum dma_data_direction direction)
924{
925 might_sleep();
926
927 if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
928 return;
929
930 if (dma_buf_attachment_is_dynamic(attach))
931 dma_resv_assert_held(attach->dmabuf->resv);
932
933 if (attach->sgt == sg_table)
934 return;
935
936 if (dma_buf_is_dynamic(attach->dmabuf))
937 dma_resv_assert_held(attach->dmabuf->resv);
938
939 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
940
941 if (dma_buf_is_dynamic(attach->dmabuf) &&
942 !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
943 dma_buf_unpin(attach);
944}
945EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
946
947/**
948 * dma_buf_move_notify - notify attachments that DMA-buf is moving
949 *
950 * @dmabuf: [in] buffer which is moving
951 *
952 * Informs all attachmenst that they need to destroy and recreated all their
953 * mappings.
954 */
955void dma_buf_move_notify(struct dma_buf *dmabuf)
956{
957 struct dma_buf_attachment *attach;
958
959 dma_resv_assert_held(dmabuf->resv);
960
961 list_for_each_entry(attach, &dmabuf->attachments, node)
962 if (attach->importer_ops)
963 attach->importer_ops->move_notify(attach);
964}
965EXPORT_SYMBOL_GPL(dma_buf_move_notify);
966
967/**
968 * DOC: cpu access
969 *
970 * There are mutliple reasons for supporting CPU access to a dma buffer object:
971 *
972 * - Fallback operations in the kernel, for example when a device is connected
973 * over USB and the kernel needs to shuffle the data around first before
974 * sending it away. Cache coherency is handled by braketing any transactions
975 * with calls to dma_buf_begin_cpu_access() and dma_buf_end_cpu_access()
976 * access.
977 *
978 * Since for most kernel internal dma-buf accesses need the entire buffer, a
979 * vmap interface is introduced. Note that on very old 32-bit architectures
980 * vmalloc space might be limited and result in vmap calls failing.
981 *
982 * Interfaces::
983 * void \*dma_buf_vmap(struct dma_buf \*dmabuf)
984 * void dma_buf_vunmap(struct dma_buf \*dmabuf, void \*vaddr)
985 *
986 * The vmap call can fail if there is no vmap support in the exporter, or if
987 * it runs out of vmalloc space. Fallback to kmap should be implemented. Note
988 * that the dma-buf layer keeps a reference count for all vmap access and
989 * calls down into the exporter's vmap function only when no vmapping exists,
990 * and only unmaps it once. Protection against concurrent vmap/vunmap calls is
991 * provided by taking the dma_buf->lock mutex.
992 *
993 * - For full compatibility on the importer side with existing userspace
994 * interfaces, which might already support mmap'ing buffers. This is needed in
995 * many processing pipelines (e.g. feeding a software rendered image into a
996 * hardware pipeline, thumbnail creation, snapshots, ...). Also, Android's ION
997 * framework already supported this and for DMA buffer file descriptors to
998 * replace ION buffers mmap support was needed.
999 *
1000 * There is no special interfaces, userspace simply calls mmap on the dma-buf
1001 * fd. But like for CPU access there's a need to braket the actual access,
1002 * which is handled by the ioctl (DMA_BUF_IOCTL_SYNC). Note that
1003 * DMA_BUF_IOCTL_SYNC can fail with -EAGAIN or -EINTR, in which case it must
1004 * be restarted.
1005 *
1006 * Some systems might need some sort of cache coherency management e.g. when
1007 * CPU and GPU domains are being accessed through dma-buf at the same time.
1008 * To circumvent this problem there are begin/end coherency markers, that
1009 * forward directly to existing dma-buf device drivers vfunc hooks. Userspace
1010 * can make use of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The
1011 * sequence would be used like following:
1012 *
1013 * - mmap dma-buf fd
1014 * - for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
1015 * to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
1016 * want (with the new data being consumed by say the GPU or the scanout
1017 * device)
1018 * - munmap once you don't need the buffer any more
1019 *
1020 * For correctness and optimal performance, it is always required to use
1021 * SYNC_START and SYNC_END before and after, respectively, when accessing the
1022 * mapped address. Userspace cannot rely on coherent access, even when there
1023 * are systems where it just works without calling these ioctls.
1024 *
1025 * - And as a CPU fallback in userspace processing pipelines.
1026 *
1027 * Similar to the motivation for kernel cpu access it is again important that
1028 * the userspace code of a given importing subsystem can use the same
1029 * interfaces with a imported dma-buf buffer object as with a native buffer
1030 * object. This is especially important for drm where the userspace part of
1031 * contemporary OpenGL, X, and other drivers is huge, and reworking them to
1032 * use a different way to mmap a buffer rather invasive.
1033 *
1034 * The assumption in the current dma-buf interfaces is that redirecting the
1035 * initial mmap is all that's needed. A survey of some of the existing
1036 * subsystems shows that no driver seems to do any nefarious thing like
1037 * syncing up with outstanding asynchronous processing on the device or
1038 * allocating special resources at fault time. So hopefully this is good
1039 * enough, since adding interfaces to intercept pagefaults and allow pte
1040 * shootdowns would increase the complexity quite a bit.
1041 *
1042 * Interface::
1043 * int dma_buf_mmap(struct dma_buf \*, struct vm_area_struct \*,
1044 * unsigned long);
1045 *
1046 * If the importing subsystem simply provides a special-purpose mmap call to
1047 * set up a mapping in userspace, calling do_mmap with dma_buf->file will
1048 * equally achieve that for a dma-buf object.
1049 */
1050
1051static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
1052 enum dma_data_direction direction)
1053{
1054 bool write = (direction == DMA_BIDIRECTIONAL ||
1055 direction == DMA_TO_DEVICE);
1056 struct dma_resv *resv = dmabuf->resv;
1057 long ret;
1058
1059 /* Wait on any implicit rendering fences */
1060 ret = dma_resv_wait_timeout_rcu(resv, write, true,
1061 MAX_SCHEDULE_TIMEOUT);
1062 if (ret < 0)
1063 return ret;
1064
1065 return 0;
1066}
1067
1068/**
1069 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
1070 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
1071 * preparations. Coherency is only guaranteed in the specified range for the
1072 * specified access direction.
1073 * @dmabuf: [in] buffer to prepare cpu access for.
1074 * @direction: [in] length of range for cpu access.
1075 *
1076 * After the cpu access is complete the caller should call
1077 * dma_buf_end_cpu_access(). Only when cpu access is braketed by both calls is
1078 * it guaranteed to be coherent with other DMA access.
1079 *
1080 * Can return negative error values, returns 0 on success.
1081 */
1082int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
1083 enum dma_data_direction direction)
1084{
1085 int ret = 0;
1086
1087 if (WARN_ON(!dmabuf))
1088 return -EINVAL;
1089
1090 if (dmabuf->ops->begin_cpu_access)
1091 ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);
1092
1093 /* Ensure that all fences are waited upon - but we first allow
1094 * the native handler the chance to do so more efficiently if it
1095 * chooses. A double invocation here will be reasonably cheap no-op.
1096 */
1097 if (ret == 0)
1098 ret = __dma_buf_begin_cpu_access(dmabuf, direction);
1099
1100 return ret;
1101}
1102EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
1103
1104/**
1105 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
1106 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
1107 * actions. Coherency is only guaranteed in the specified range for the
1108 * specified access direction.
1109 * @dmabuf: [in] buffer to complete cpu access for.
1110 * @direction: [in] length of range for cpu access.
1111 *
1112 * This terminates CPU access started with dma_buf_begin_cpu_access().
1113 *
1114 * Can return negative error values, returns 0 on success.
1115 */
1116int dma_buf_end_cpu_access(struct dma_buf *dmabuf,
1117 enum dma_data_direction direction)
1118{
1119 int ret = 0;
1120
1121 WARN_ON(!dmabuf);
1122
1123 if (dmabuf->ops->end_cpu_access)
1124 ret = dmabuf->ops->end_cpu_access(dmabuf, direction);
1125
1126 return ret;
1127}
1128EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
1129
1130
1131/**
1132 * dma_buf_mmap - Setup up a userspace mmap with the given vma
1133 * @dmabuf: [in] buffer that should back the vma
1134 * @vma: [in] vma for the mmap
1135 * @pgoff: [in] offset in pages where this mmap should start within the
1136 * dma-buf buffer.
1137 *
1138 * This function adjusts the passed in vma so that it points at the file of the
1139 * dma_buf operation. It also adjusts the starting pgoff and does bounds
1140 * checking on the size of the vma. Then it calls the exporters mmap function to
1141 * set up the mapping.
1142 *
1143 * Can return negative error values, returns 0 on success.
1144 */
1145int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
1146 unsigned long pgoff)
1147{
1148 struct file *oldfile;
1149 int ret;
1150
1151 if (WARN_ON(!dmabuf || !vma))
1152 return -EINVAL;
1153
1154 /* check if buffer supports mmap */
1155 if (!dmabuf->ops->mmap)
1156 return -EINVAL;
1157
1158 /* check for offset overflow */
1159 if (pgoff + vma_pages(vma) < pgoff)
1160 return -EOVERFLOW;
1161
1162 /* check for overflowing the buffer's size */
1163 if (pgoff + vma_pages(vma) >
1164 dmabuf->size >> PAGE_SHIFT)
1165 return -EINVAL;
1166
1167 /* readjust the vma */
1168 get_file(dmabuf->file);
1169 oldfile = vma->vm_file;
1170 vma->vm_file = dmabuf->file;
1171 vma->vm_pgoff = pgoff;
1172
1173 ret = dmabuf->ops->mmap(dmabuf, vma);
1174 if (ret) {
1175 /* restore old parameters on failure */
1176 vma->vm_file = oldfile;
1177 fput(dmabuf->file);
1178 } else {
1179 if (oldfile)
1180 fput(oldfile);
1181 }
1182 return ret;
1183
1184}
1185EXPORT_SYMBOL_GPL(dma_buf_mmap);
1186
1187/**
1188 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
1189 * address space. Same restrictions as for vmap and friends apply.
1190 * @dmabuf: [in] buffer to vmap
1191 *
1192 * This call may fail due to lack of virtual mapping address space.
1193 * These calls are optional in drivers. The intended use for them
1194 * is for mapping objects linear in kernel space for high use objects.
1195 * Please attempt to use kmap/kunmap before thinking about these interfaces.
1196 *
1197 * Returns NULL on error.
1198 */
1199void *dma_buf_vmap(struct dma_buf *dmabuf)
1200{
1201 void *ptr;
1202
1203 if (WARN_ON(!dmabuf))
1204 return NULL;
1205
1206 if (!dmabuf->ops->vmap)
1207 return NULL;
1208
1209 mutex_lock(&dmabuf->lock);
1210 if (dmabuf->vmapping_counter) {
1211 dmabuf->vmapping_counter++;
1212 BUG_ON(!dmabuf->vmap_ptr);
1213 ptr = dmabuf->vmap_ptr;
1214 goto out_unlock;
1215 }
1216
1217 BUG_ON(dmabuf->vmap_ptr);
1218
1219 ptr = dmabuf->ops->vmap(dmabuf);
1220 if (WARN_ON_ONCE(IS_ERR(ptr)))
1221 ptr = NULL;
1222 if (!ptr)
1223 goto out_unlock;
1224
1225 dmabuf->vmap_ptr = ptr;
1226 dmabuf->vmapping_counter = 1;
1227
1228out_unlock:
1229 mutex_unlock(&dmabuf->lock);
1230 return ptr;
1231}
1232EXPORT_SYMBOL_GPL(dma_buf_vmap);
1233
1234/**
1235 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
1236 * @dmabuf: [in] buffer to vunmap
1237 * @vaddr: [in] vmap to vunmap
1238 */
1239void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
1240{
1241 if (WARN_ON(!dmabuf))
1242 return;
1243
1244 BUG_ON(!dmabuf->vmap_ptr);
1245 BUG_ON(dmabuf->vmapping_counter == 0);
1246 BUG_ON(dmabuf->vmap_ptr != vaddr);
1247
1248 mutex_lock(&dmabuf->lock);
1249 if (--dmabuf->vmapping_counter == 0) {
1250 if (dmabuf->ops->vunmap)
1251 dmabuf->ops->vunmap(dmabuf, vaddr);
1252 dmabuf->vmap_ptr = NULL;
1253 }
1254 mutex_unlock(&dmabuf->lock);
1255}
1256EXPORT_SYMBOL_GPL(dma_buf_vunmap);
1257
1258#ifdef CONFIG_DEBUG_FS
1259static int dma_buf_debug_show(struct seq_file *s, void *unused)
1260{
1261 int ret;
1262 struct dma_buf *buf_obj;
1263 struct dma_buf_attachment *attach_obj;
1264 struct dma_resv *robj;
1265 struct dma_resv_list *fobj;
1266 struct dma_fence *fence;
1267 unsigned seq;
1268 int count = 0, attach_count, shared_count, i;
1269 size_t size = 0;
1270
1271 ret = mutex_lock_interruptible(&db_list.lock);
1272
1273 if (ret)
1274 return ret;
1275
1276 seq_puts(s, "\nDma-buf Objects:\n");
1277 seq_printf(s, "%-8s\t%-8s\t%-8s\t%-8s\texp_name\t%-8s\n",
1278 "size", "flags", "mode", "count", "ino");
1279
1280 list_for_each_entry(buf_obj, &db_list.head, list_node) {
1281
1282 ret = dma_resv_lock_interruptible(buf_obj->resv, NULL);
1283 if (ret)
1284 goto error_unlock;
1285
1286 seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
1287 buf_obj->size,
1288 buf_obj->file->f_flags, buf_obj->file->f_mode,
1289 file_count(buf_obj->file),
1290 buf_obj->exp_name,
1291 file_inode(buf_obj->file)->i_ino,
1292 buf_obj->name ?: "");
1293
1294 robj = buf_obj->resv;
1295 while (true) {
1296 seq = read_seqcount_begin(&robj->seq);
1297 rcu_read_lock();
1298 fobj = rcu_dereference(robj->fence);
1299 shared_count = fobj ? fobj->shared_count : 0;
1300 fence = rcu_dereference(robj->fence_excl);
1301 if (!read_seqcount_retry(&robj->seq, seq))
1302 break;
1303 rcu_read_unlock();
1304 }
1305
1306 if (fence)
1307 seq_printf(s, "\tExclusive fence: %s %s %ssignalled\n",
1308 fence->ops->get_driver_name(fence),
1309 fence->ops->get_timeline_name(fence),
1310 dma_fence_is_signaled(fence) ? "" : "un");
1311 for (i = 0; i < shared_count; i++) {
1312 fence = rcu_dereference(fobj->shared[i]);
1313 if (!dma_fence_get_rcu(fence))
1314 continue;
1315 seq_printf(s, "\tShared fence: %s %s %ssignalled\n",
1316 fence->ops->get_driver_name(fence),
1317 fence->ops->get_timeline_name(fence),
1318 dma_fence_is_signaled(fence) ? "" : "un");
1319 dma_fence_put(fence);
1320 }
1321 rcu_read_unlock();
1322
1323 seq_puts(s, "\tAttached Devices:\n");
1324 attach_count = 0;
1325
1326 list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
1327 seq_printf(s, "\t%s\n", dev_name(attach_obj->dev));
1328 attach_count++;
1329 }
1330 dma_resv_unlock(buf_obj->resv);
1331
1332 seq_printf(s, "Total %d devices attached\n\n",
1333 attach_count);
1334
1335 count++;
1336 size += buf_obj->size;
1337 }
1338
1339 seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
1340
1341 mutex_unlock(&db_list.lock);
1342 return 0;
1343
1344error_unlock:
1345 mutex_unlock(&db_list.lock);
1346 return ret;
1347}
1348
1349DEFINE_SHOW_ATTRIBUTE(dma_buf_debug);
1350
1351static struct dentry *dma_buf_debugfs_dir;
1352
1353static int dma_buf_init_debugfs(void)
1354{
1355 struct dentry *d;
1356 int err = 0;
1357
1358 d = debugfs_create_dir("dma_buf", NULL);
1359 if (IS_ERR(d))
1360 return PTR_ERR(d);
1361
1362 dma_buf_debugfs_dir = d;
1363
1364 d = debugfs_create_file("bufinfo", S_IRUGO, dma_buf_debugfs_dir,
1365 NULL, &dma_buf_debug_fops);
1366 if (IS_ERR(d)) {
1367 pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
1368 debugfs_remove_recursive(dma_buf_debugfs_dir);
1369 dma_buf_debugfs_dir = NULL;
1370 err = PTR_ERR(d);
1371 }
1372
1373 return err;
1374}
1375
1376static void dma_buf_uninit_debugfs(void)
1377{
1378 debugfs_remove_recursive(dma_buf_debugfs_dir);
1379}
1380#else
1381static inline int dma_buf_init_debugfs(void)
1382{
1383 return 0;
1384}
1385static inline void dma_buf_uninit_debugfs(void)
1386{
1387}
1388#endif
1389
1390static int __init dma_buf_init(void)
1391{
1392 dma_buf_mnt = kern_mount(&dma_buf_fs_type);
1393 if (IS_ERR(dma_buf_mnt))
1394 return PTR_ERR(dma_buf_mnt);
1395
1396 mutex_init(&db_list.lock);
1397 INIT_LIST_HEAD(&db_list.head);
1398 dma_buf_init_debugfs();
1399 return 0;
1400}
1401subsys_initcall(dma_buf_init);
1402
1403static void __exit dma_buf_deinit(void)
1404{
1405 dma_buf_uninit_debugfs();
1406 kern_unmount(dma_buf_mnt);
1407}
1408__exitcall(dma_buf_deinit);