/* * Framework for buffer objects that can be shared across devices/subsystems. * * Copyright(C) 2011 Linaro Limited. All rights reserved. * Author: Sumit Semwal * * Many thanks to linaro-mm-sig list, and specially * Arnd Bergmann , Rob Clark and * Daniel Vetter for their support in creation and * refining of this idea. * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published by * the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for * more details. * * You should have received a copy of the GNU General Public License along with * this program. If not, see . */ #include #include #include #include #include #include #include #include #include #include #include static inline int is_dma_buf_file(struct file *); struct dma_buf_list { struct list_head head; struct mutex lock; }; static struct dma_buf_list db_list; static int dma_buf_release(struct inode *inode, struct file *file) { struct dma_buf *dmabuf; if (!is_dma_buf_file(file)) return -EINVAL; dmabuf = file->private_data; BUG_ON(dmabuf->vmapping_counter); /* * Any fences that a dma-buf poll can wait on should be signaled * before releasing dma-buf. This is the responsibility of each * driver that uses the reservation objects. * * If you hit this BUG() it means someone dropped their ref to the * dma-buf while still having pending operation to the buffer. */ BUG_ON(dmabuf->cb_shared.active || dmabuf->cb_excl.active); dmabuf->ops->release(dmabuf); mutex_lock(&db_list.lock); list_del(&dmabuf->list_node); mutex_unlock(&db_list.lock); if (dmabuf->resv == (struct reservation_object *)&dmabuf[1]) reservation_object_fini(dmabuf->resv); module_put(dmabuf->owner); kfree(dmabuf); return 0; } static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma) { struct dma_buf *dmabuf; if (!is_dma_buf_file(file)) return -EINVAL; dmabuf = file->private_data; /* check for overflowing the buffer's size */ if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) > dmabuf->size >> PAGE_SHIFT) return -EINVAL; return dmabuf->ops->mmap(dmabuf, vma); } static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence) { struct dma_buf *dmabuf; loff_t base; if (!is_dma_buf_file(file)) return -EBADF; dmabuf = file->private_data; /* only support discovering the end of the buffer, but also allow SEEK_SET to maintain the idiomatic SEEK_END(0), SEEK_CUR(0) pattern */ if (whence == SEEK_END) base = dmabuf->size; else if (whence == SEEK_SET) base = 0; else return -EINVAL; if (offset != 0) return -EINVAL; return base + offset; } static void dma_buf_poll_cb(struct fence *fence, struct fence_cb *cb) { struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb; unsigned long flags; spin_lock_irqsave(&dcb->poll->lock, flags); wake_up_locked_poll(dcb->poll, dcb->active); dcb->active = 0; spin_unlock_irqrestore(&dcb->poll->lock, flags); } static unsigned int dma_buf_poll(struct file *file, poll_table *poll) { struct dma_buf *dmabuf; struct reservation_object *resv; struct reservation_object_list *fobj; struct fence *fence_excl; unsigned long events; unsigned shared_count, seq; dmabuf = file->private_data; if (!dmabuf || !dmabuf->resv) return POLLERR; resv = dmabuf->resv; poll_wait(file, &dmabuf->poll, poll); events = poll_requested_events(poll) & (POLLIN | POLLOUT); if (!events) return 0; retry: seq = read_seqcount_begin(&resv->seq); rcu_read_lock(); fobj = rcu_dereference(resv->fence); if (fobj) shared_count = fobj->shared_count; else shared_count = 0; fence_excl = rcu_dereference(resv->fence_excl); if (read_seqcount_retry(&resv->seq, seq)) { rcu_read_unlock(); goto retry; } if (fence_excl && (!(events & POLLOUT) || shared_count == 0)) { struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_excl; unsigned long pevents = POLLIN; if (shared_count == 0) pevents |= POLLOUT; spin_lock_irq(&dmabuf->poll.lock); if (dcb->active) { dcb->active |= pevents; events &= ~pevents; } else dcb->active = pevents; spin_unlock_irq(&dmabuf->poll.lock); if (events & pevents) { if (!fence_get_rcu(fence_excl)) { /* force a recheck */ events &= ~pevents; dma_buf_poll_cb(NULL, &dcb->cb); } else if (!fence_add_callback(fence_excl, &dcb->cb, dma_buf_poll_cb)) { events &= ~pevents; fence_put(fence_excl); } else { /* * No callback queued, wake up any additional * waiters. */ fence_put(fence_excl); dma_buf_poll_cb(NULL, &dcb->cb); } } } if ((events & POLLOUT) && shared_count > 0) { struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_shared; int i; /* Only queue a new callback if no event has fired yet */ spin_lock_irq(&dmabuf->poll.lock); if (dcb->active) events &= ~POLLOUT; else dcb->active = POLLOUT; spin_unlock_irq(&dmabuf->poll.lock); if (!(events & POLLOUT)) goto out; for (i = 0; i < shared_count; ++i) { struct fence *fence = rcu_dereference(fobj->shared[i]); if (!fence_get_rcu(fence)) { /* * fence refcount dropped to zero, this means * that fobj has been freed * * call dma_buf_poll_cb and force a recheck! */ events &= ~POLLOUT; dma_buf_poll_cb(NULL, &dcb->cb); break; } if (!fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb)) { fence_put(fence); events &= ~POLLOUT; break; } fence_put(fence); } /* No callback queued, wake up any additional waiters. */ if (i == shared_count) dma_buf_poll_cb(NULL, &dcb->cb); } out: rcu_read_unlock(); return events; } static const struct file_operations dma_buf_fops = { .release = dma_buf_release, .mmap = dma_buf_mmap_internal, .llseek = dma_buf_llseek, .poll = dma_buf_poll, }; /* * is_dma_buf_file - Check if struct file* is associated with dma_buf */ static inline int is_dma_buf_file(struct file *file) { return file->f_op == &dma_buf_fops; } /** * dma_buf_export - Creates a new dma_buf, and associates an anon file * with this buffer, so it can be exported. * Also connect the allocator specific data and ops to the buffer. * Additionally, provide a name string for exporter; useful in debugging. * * @exp_info: [in] holds all the export related information provided * by the exporter. see struct dma_buf_export_info * for further details. * * Returns, on success, a newly created dma_buf object, which wraps the * supplied private data and operations for dma_buf_ops. On either missing * ops, or error in allocating struct dma_buf, will return negative error. * */ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) { struct dma_buf *dmabuf; struct reservation_object *resv = exp_info->resv; struct file *file; size_t alloc_size = sizeof(struct dma_buf); if (!exp_info->resv) alloc_size += sizeof(struct reservation_object); else /* prevent &dma_buf[1] == dma_buf->resv */ alloc_size += 1; if (WARN_ON(!exp_info->priv || !exp_info->ops || !exp_info->ops->map_dma_buf || !exp_info->ops->unmap_dma_buf || !exp_info->ops->release || !exp_info->ops->kmap_atomic || !exp_info->ops->kmap || !exp_info->ops->mmap)) { return ERR_PTR(-EINVAL); } if (!try_module_get(exp_info->owner)) return ERR_PTR(-ENOENT); dmabuf = kzalloc(alloc_size, GFP_KERNEL); if (!dmabuf) { module_put(exp_info->owner); return ERR_PTR(-ENOMEM); } dmabuf->priv = exp_info->priv; dmabuf->ops = exp_info->ops; dmabuf->size = exp_info->size; dmabuf->exp_name = exp_info->exp_name; dmabuf->owner = exp_info->owner; init_waitqueue_head(&dmabuf->poll); dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll; dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0; if (!resv) { resv = (struct reservation_object *)&dmabuf[1]; reservation_object_init(resv); } dmabuf->resv = resv; file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, exp_info->flags); if (IS_ERR(file)) { kfree(dmabuf); return ERR_CAST(file); } file->f_mode |= FMODE_LSEEK; dmabuf->file = file; mutex_init(&dmabuf->lock); INIT_LIST_HEAD(&dmabuf->attachments); mutex_lock(&db_list.lock); list_add(&dmabuf->list_node, &db_list.head); mutex_unlock(&db_list.lock); return dmabuf; } EXPORT_SYMBOL_GPL(dma_buf_export); /** * dma_buf_fd - returns a file descriptor for the given dma_buf * @dmabuf: [in] pointer to dma_buf for which fd is required. * @flags: [in] flags to give to fd * * On success, returns an associated 'fd'. Else, returns error. */ int dma_buf_fd(struct dma_buf *dmabuf, int flags) { int fd; if (!dmabuf || !dmabuf->file) return -EINVAL; fd = get_unused_fd_flags(flags); if (fd < 0) return fd; fd_install(fd, dmabuf->file); return fd; } EXPORT_SYMBOL_GPL(dma_buf_fd); /** * dma_buf_get - returns the dma_buf structure related to an fd * @fd: [in] fd associated with the dma_buf to be returned * * On success, returns the dma_buf structure associated with an fd; uses * file's refcounting done by fget to increase refcount. returns ERR_PTR * otherwise. */ struct dma_buf *dma_buf_get(int fd) { struct file *file; file = fget(fd); if (!file) return ERR_PTR(-EBADF); if (!is_dma_buf_file(file)) { fput(file); return ERR_PTR(-EINVAL); } return file->private_data; } EXPORT_SYMBOL_GPL(dma_buf_get); /** * dma_buf_put - decreases refcount of the buffer * @dmabuf: [in] buffer to reduce refcount of * * Uses file's refcounting done implicitly by fput() */ void dma_buf_put(struct dma_buf *dmabuf) { if (WARN_ON(!dmabuf || !dmabuf->file)) return; fput(dmabuf->file); } EXPORT_SYMBOL_GPL(dma_buf_put); /** * dma_buf_attach - Add the device to dma_buf's attachments list; optionally, * calls attach() of dma_buf_ops to allow device-specific attach functionality * @dmabuf: [in] buffer to attach device to. * @dev: [in] device to be attached. * * Returns struct dma_buf_attachment * for this attachment; returns ERR_PTR on * error. */ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, struct device *dev) { struct dma_buf_attachment *attach; int ret; if (WARN_ON(!dmabuf || !dev)) return ERR_PTR(-EINVAL); attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL); if (attach == NULL) return ERR_PTR(-ENOMEM); attach->dev = dev; attach->dmabuf = dmabuf; mutex_lock(&dmabuf->lock); if (dmabuf->ops->attach) { ret = dmabuf->ops->attach(dmabuf, dev, attach); if (ret) goto err_attach; } list_add(&attach->node, &dmabuf->attachments); mutex_unlock(&dmabuf->lock); return attach; err_attach: kfree(attach); mutex_unlock(&dmabuf->lock); return ERR_PTR(ret); } EXPORT_SYMBOL_GPL(dma_buf_attach); /** * dma_buf_detach - Remove the given attachment from dmabuf's attachments list; * optionally calls detach() of dma_buf_ops for device-specific detach * @dmabuf: [in] buffer to detach from. * @attach: [in] attachment to be detached; is free'd after this call. * */ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) { if (WARN_ON(!dmabuf || !attach)) return; mutex_lock(&dmabuf->lock); list_del(&attach->node); if (dmabuf->ops->detach) dmabuf->ops->detach(dmabuf, attach); mutex_unlock(&dmabuf->lock); kfree(attach); } EXPORT_SYMBOL_GPL(dma_buf_detach); /** * dma_buf_map_attachment - Returns the scatterlist table of the attachment; * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the * dma_buf_ops. * @attach: [in] attachment whose scatterlist is to be returned * @direction: [in] direction of DMA transfer * * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR * on error. */ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, enum dma_data_direction direction) { struct sg_table *sg_table = ERR_PTR(-EINVAL); might_sleep(); if (WARN_ON(!attach || !attach->dmabuf)) return ERR_PTR(-EINVAL); sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction); if (!sg_table) sg_table = ERR_PTR(-ENOMEM); return sg_table; } EXPORT_SYMBOL_GPL(dma_buf_map_attachment); /** * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of * dma_buf_ops. * @attach: [in] attachment to unmap buffer from * @sg_table: [in] scatterlist info of the buffer to unmap * @direction: [in] direction of DMA transfer * */ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, struct sg_table *sg_table, enum dma_data_direction direction) { might_sleep(); if (WARN_ON(!attach || !attach->dmabuf || !sg_table)) return; attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction); } EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment); /** * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific * preparations. Coherency is only guaranteed in the specified range for the * specified access direction. * @dmabuf: [in] buffer to prepare cpu access for. * @direction: [in] length of range for cpu access. * * Can return negative error values, returns 0 on success. */ int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction) { int ret = 0; if (WARN_ON(!dmabuf)) return -EINVAL; if (dmabuf->ops->begin_cpu_access) ret = dmabuf->ops->begin_cpu_access(dmabuf, direction); return ret; } EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access); /** * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific * actions. Coherency is only guaranteed in the specified range for the * specified access direction. * @dmabuf: [in] buffer to complete cpu access for. * @direction: [in] length of range for cpu access. * * This call must always succeed. */ void dma_buf_end_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction) { WARN_ON(!dmabuf); if (dmabuf->ops->end_cpu_access) dmabuf->ops->end_cpu_access(dmabuf, direction); } EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access); /** * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address * space. The same restrictions as for kmap_atomic and friends apply. * @dmabuf: [in] buffer to map page from. * @page_num: [in] page in PAGE_SIZE units to map. * * This call must always succeed, any necessary preparations that might fail * need to be done in begin_cpu_access. */ void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num) { WARN_ON(!dmabuf); return dmabuf->ops->kmap_atomic(dmabuf, page_num); } EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic); /** * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic. * @dmabuf: [in] buffer to unmap page from. * @page_num: [in] page in PAGE_SIZE units to unmap. * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap_atomic. * * This call must always succeed. */ void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num, void *vaddr) { WARN_ON(!dmabuf); if (dmabuf->ops->kunmap_atomic) dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr); } EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic); /** * dma_buf_kmap - Map a page of the buffer object into kernel address space. The * same restrictions as for kmap and friends apply. * @dmabuf: [in] buffer to map page from. * @page_num: [in] page in PAGE_SIZE units to map. * * This call must always succeed, any necessary preparations that might fail * need to be done in begin_cpu_access. */ void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num) { WARN_ON(!dmabuf); return dmabuf->ops->kmap(dmabuf, page_num); } EXPORT_SYMBOL_GPL(dma_buf_kmap); /** * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap. * @dmabuf: [in] buffer to unmap page from. * @page_num: [in] page in PAGE_SIZE units to unmap. * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap. * * This call must always succeed. */ void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num, void *vaddr) { WARN_ON(!dmabuf); if (dmabuf->ops->kunmap) dmabuf->ops->kunmap(dmabuf, page_num, vaddr); } EXPORT_SYMBOL_GPL(dma_buf_kunmap); /** * dma_buf_mmap - Setup up a userspace mmap with the given vma * @dmabuf: [in] buffer that should back the vma * @vma: [in] vma for the mmap * @pgoff: [in] offset in pages where this mmap should start within the * dma-buf buffer. * * This function adjusts the passed in vma so that it points at the file of the * dma_buf operation. It also adjusts the starting pgoff and does bounds * checking on the size of the vma. Then it calls the exporters mmap function to * set up the mapping. * * Can return negative error values, returns 0 on success. */ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, unsigned long pgoff) { struct file *oldfile; int ret; if (WARN_ON(!dmabuf || !vma)) return -EINVAL; /* check for offset overflow */ if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff) return -EOVERFLOW; /* check for overflowing the buffer's size */ if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) > dmabuf->size >> PAGE_SHIFT) return -EINVAL; /* readjust the vma */ get_file(dmabuf->file); oldfile = vma->vm_file; vma->vm_file = dmabuf->file; vma->vm_pgoff = pgoff; ret = dmabuf->ops->mmap(dmabuf, vma); if (ret) { /* restore old parameters on failure */ vma->vm_file = oldfile; fput(dmabuf->file); } else { if (oldfile) fput(oldfile); } return ret; } EXPORT_SYMBOL_GPL(dma_buf_mmap); /** * dma_buf_vmap - Create virtual mapping for the buffer object into kernel * address space. Same restrictions as for vmap and friends apply. * @dmabuf: [in] buffer to vmap * * This call may fail due to lack of virtual mapping address space. * These calls are optional in drivers. The intended use for them * is for mapping objects linear in kernel space for high use objects. * Please attempt to use kmap/kunmap before thinking about these interfaces. * * Returns NULL on error. */ void *dma_buf_vmap(struct dma_buf *dmabuf) { void *ptr; if (WARN_ON(!dmabuf)) return NULL; if (!dmabuf->ops->vmap) return NULL; mutex_lock(&dmabuf->lock); if (dmabuf->vmapping_counter) { dmabuf->vmapping_counter++; BUG_ON(!dmabuf->vmap_ptr); ptr = dmabuf->vmap_ptr; goto out_unlock; } BUG_ON(dmabuf->vmap_ptr); ptr = dmabuf->ops->vmap(dmabuf); if (WARN_ON_ONCE(IS_ERR(ptr))) ptr = NULL; if (!ptr) goto out_unlock; dmabuf->vmap_ptr = ptr; dmabuf->vmapping_counter = 1; out_unlock: mutex_unlock(&dmabuf->lock); return ptr; } EXPORT_SYMBOL_GPL(dma_buf_vmap); /** * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap. * @dmabuf: [in] buffer to vunmap * @vaddr: [in] vmap to vunmap */ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr) { if (WARN_ON(!dmabuf)) return; BUG_ON(!dmabuf->vmap_ptr); BUG_ON(dmabuf->vmapping_counter == 0); BUG_ON(dmabuf->vmap_ptr != vaddr); mutex_lock(&dmabuf->lock); if (--dmabuf->vmapping_counter == 0) { if (dmabuf->ops->vunmap) dmabuf->ops->vunmap(dmabuf, vaddr); dmabuf->vmap_ptr = NULL; } mutex_unlock(&dmabuf->lock); } EXPORT_SYMBOL_GPL(dma_buf_vunmap); #ifdef CONFIG_DEBUG_FS static int dma_buf_describe(struct seq_file *s) { int ret; struct dma_buf *buf_obj; struct dma_buf_attachment *attach_obj; int count = 0, attach_count; size_t size = 0; ret = mutex_lock_interruptible(&db_list.lock); if (ret) return ret; seq_puts(s, "\nDma-buf Objects:\n"); seq_puts(s, "size\tflags\tmode\tcount\texp_name\n"); list_for_each_entry(buf_obj, &db_list.head, list_node) { ret = mutex_lock_interruptible(&buf_obj->lock); if (ret) { seq_puts(s, "\tERROR locking buffer object: skipping\n"); continue; } seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\n", buf_obj->size, buf_obj->file->f_flags, buf_obj->file->f_mode, file_count(buf_obj->file), buf_obj->exp_name); seq_puts(s, "\tAttached Devices:\n"); attach_count = 0; list_for_each_entry(attach_obj, &buf_obj->attachments, node) { seq_puts(s, "\t"); seq_printf(s, "%s\n", dev_name(attach_obj->dev)); attach_count++; } seq_printf(s, "Total %d devices attached\n\n", attach_count); count++; size += buf_obj->size; mutex_unlock(&buf_obj->lock); } seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size); mutex_unlock(&db_list.lock); return 0; } static int dma_buf_show(struct seq_file *s, void *unused) { void (*func)(struct seq_file *) = s->private; func(s); return 0; } static int dma_buf_debug_open(struct inode *inode, struct file *file) { return single_open(file, dma_buf_show, inode->i_private); } static const struct file_operations dma_buf_debug_fops = { .open = dma_buf_debug_open, .read = seq_read, .llseek = seq_lseek, .release = single_release, }; static struct dentry *dma_buf_debugfs_dir; static int dma_buf_init_debugfs(void) { int err = 0; dma_buf_debugfs_dir = debugfs_create_dir("dma_buf", NULL); if (IS_ERR(dma_buf_debugfs_dir)) { err = PTR_ERR(dma_buf_debugfs_dir); dma_buf_debugfs_dir = NULL; return err; } err = dma_buf_debugfs_create_file("bufinfo", dma_buf_describe); if (err) pr_debug("dma_buf: debugfs: failed to create node bufinfo\n"); return err; } static void dma_buf_uninit_debugfs(void) { if (dma_buf_debugfs_dir) debugfs_remove_recursive(dma_buf_debugfs_dir); } int dma_buf_debugfs_create_file(const char *name, int (*write)(struct seq_file *)) { struct dentry *d; d = debugfs_create_file(name, S_IRUGO, dma_buf_debugfs_dir, write, &dma_buf_debug_fops); return PTR_ERR_OR_ZERO(d); } #else static inline int dma_buf_init_debugfs(void) { return 0; } static inline void dma_buf_uninit_debugfs(void) { } #endif static int __init dma_buf_init(void) { mutex_init(&db_list.lock); INIT_LIST_HEAD(&db_list.head); dma_buf_init_debugfs(); return 0; } subsys_initcall(dma_buf_init); static void __exit dma_buf_deinit(void) { dma_buf_uninit_debugfs(); } __exitcall(dma_buf_deinit);