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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Framework for buffer objects that can be shared across devices/subsystems.
  *
  * Copyright(C) 2011 Linaro Limited. All rights reserved.
  * Author: Sumit Semwal <sumit.semwal@ti.com>
  *
  * Many thanks to linaro-mm-sig list, and specially
  * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
  * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
  * refining of this idea.
  */
 
 #include <linux/fs.h>
 #include <linux/slab.h>
 #include <linux/dma-buf.h>
 #include <linux/dma-fence.h>
 #include <linux/anon_inodes.h>
 #include <linux/export.h>
 #include <linux/debugfs.h>
 #include <linux/module.h>
 #include <linux/seq_file.h>
 #include <linux/sync_file.h>
 #include <linux/poll.h>
 #include <linux/dma-resv.h>
 #include <linux/mm.h>
 #include <linux/mount.h>
 #include <linux/pseudo_fs.h>
 
 #include <uapi/linux/dma-buf.h>
 #include <uapi/linux/magic.h>
 
 #include "dma-buf-sysfs-stats.h"
 
 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 char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
 {
     struct dma_buf *dmabuf;
     char name[DMA_BUF_NAME_LEN];
     size_t ret = 0;
 
     dmabuf = dentry->d_fsdata;
     spin_lock(&dmabuf->name_lock);
     if (dmabuf->name)
         ret = strlcpy(name, dmabuf->name, DMA_BUF_NAME_LEN);
     spin_unlock(&dmabuf->name_lock);
 
     return dynamic_dname(dentry, buffer, buflen, "/%s:%s",
                  dentry->d_name.name, ret > 0 ? name : "");
 }
 
 static void dma_buf_release(struct dentry *dentry)
 {
     struct dma_buf *dmabuf;
 
     dmabuf = dentry->d_fsdata;
     if (unlikely(!dmabuf))
         return;
 
     BUG_ON(dmabuf->vmapping_counter);
 
     /*
      * If you hit this BUG() it could mean:
      * * There's a file reference imbalance in dma_buf_poll / dma_buf_poll_cb or somewhere else
      * * dmabuf->cb_in/out.active are non-0 despite no pending fence callback
      */
     BUG_ON(dmabuf->cb_in.active || dmabuf->cb_out.active);
 
     dma_buf_stats_teardown(dmabuf);
     dmabuf->ops->release(dmabuf);
 
     if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
         dma_resv_fini(dmabuf->resv);
 
     WARN_ON(!list_empty(&dmabuf->attachments));
     module_put(dmabuf->owner);
     kfree(dmabuf->name);
     kfree(dmabuf);
 }
 
 static int dma_buf_file_release(struct inode *inode, struct file *file)
 {
     struct dma_buf *dmabuf;
 
     if (!is_dma_buf_file(file))
         return -EINVAL;
 
     dmabuf = file->private_data;
 
     mutex_lock(&db_list.lock);
     list_del(&dmabuf->list_node);
     mutex_unlock(&db_list.lock);
 
     return 0;
 }
 
 static const struct dentry_operations dma_buf_dentry_ops = {
     .d_dname = dmabuffs_dname,
     .d_release = dma_buf_release,
 };
 
 static struct vfsmount *dma_buf_mnt;
 
 static int dma_buf_fs_init_context(struct fs_context *fc)
 {
     struct pseudo_fs_context *ctx;
 
     ctx = init_pseudo(fc, DMA_BUF_MAGIC);
     if (!ctx)
         return -ENOMEM;
     ctx->dops = &dma_buf_dentry_ops;
     return 0;
 }
 
 static struct file_system_type dma_buf_fs_type = {
     .name = "dmabuf",
     .init_fs_context = dma_buf_fs_init_context,
     .kill_sb = kill_anon_super,
 };
 
 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 if buffer supports mmap */
     if (!dmabuf->ops->mmap)
         return -EINVAL;
 
     /* check for overflowing the buffer's size */
     if (vma->vm_pgoff + vma_pages(vma) >
         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;
 }
 
 /**
  * DOC: implicit fence polling
  *
  * To support cross-device and cross-driver synchronization of buffer access
  * implicit fences (represented internally in the kernel with &struct dma_fence)
  * can be attached to a &dma_buf. The glue for that and a few related things are
  * provided in the &dma_resv structure.
  *
  * Userspace can query the state of these implicitly tracked fences using poll()
  * and related system calls:
  *
  * - Checking for EPOLLIN, i.e. read access, can be use to query the state of the
  *   most recent write or exclusive fence.
  *
  * - Checking for EPOLLOUT, i.e. write access, can be used to query the state of
  *   all attached fences, shared and exclusive ones.
  *
  * Note that this only signals the completion of the respective fences, i.e. the
  * DMA transfers are complete. Cache flushing and any other necessary
  * preparations before CPU access can begin still need to happen.
  *
  * As an alternative to poll(), the set of fences on DMA buffer can be
  * exported as a &sync_file using &dma_buf_sync_file_export.
  */
 
 static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 {
     struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;
     struct dma_buf *dmabuf = container_of(dcb->poll, struct dma_buf, poll);
     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);
     dma_fence_put(fence);
     /* Paired with get_file in dma_buf_poll */
     fput(dmabuf->file);
 }
 
 static bool dma_buf_poll_add_cb(struct dma_resv *resv, bool write,
                 struct dma_buf_poll_cb_t *dcb)
 {
     struct dma_resv_iter cursor;
     struct dma_fence *fence;
     int r;
 
     dma_resv_for_each_fence(&cursor, resv, dma_resv_usage_rw(write),
                 fence) {
         dma_fence_get(fence);
         r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);
         if (!r)
             return true;
         dma_fence_put(fence);
     }
 
     return false;
 }
 
 static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
 {
     struct dma_buf *dmabuf;
     struct dma_resv *resv;
     __poll_t events;
 
     dmabuf = file->private_data;
     if (!dmabuf || !dmabuf->resv)
         return EPOLLERR;
 
     resv = dmabuf->resv;
 
     poll_wait(file, &dmabuf->poll, poll);
 
     events = poll_requested_events(poll) & (EPOLLIN | EPOLLOUT);
     if (!events)
         return 0;
 
     dma_resv_lock(resv, NULL);
 
     if (events & EPOLLOUT) {
         struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_out;
 
         /* Check that callback isn't busy */
         spin_lock_irq(&dmabuf->poll.lock);
         if (dcb->active)
             events &= ~EPOLLOUT;
         else
             dcb->active = EPOLLOUT;
         spin_unlock_irq(&dmabuf->poll.lock);
 
         if (events & EPOLLOUT) {
             /* Paired with fput in dma_buf_poll_cb */
             get_file(dmabuf->file);
 
             if (!dma_buf_poll_add_cb(resv, true, dcb))
                 /* No callback queued, wake up any other waiters */
                 dma_buf_poll_cb(NULL, &dcb->cb);
             else
                 events &= ~EPOLLOUT;
         }
     }
 
     if (events & EPOLLIN) {
         struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_in;
 
         /* Check that callback isn't busy */
         spin_lock_irq(&dmabuf->poll.lock);
         if (dcb->active)
             events &= ~EPOLLIN;
         else
             dcb->active = EPOLLIN;
         spin_unlock_irq(&dmabuf->poll.lock);
 
         if (events & EPOLLIN) {
             /* Paired with fput in dma_buf_poll_cb */
             get_file(dmabuf->file);
 
             if (!dma_buf_poll_add_cb(resv, false, dcb))
                 /* No callback queued, wake up any other waiters */
                 dma_buf_poll_cb(NULL, &dcb->cb);
             else
                 events &= ~EPOLLIN;
         }
     }
 
     dma_resv_unlock(resv);
     return events;
 }
 
 /**
  * dma_buf_set_name - Set a name to a specific dma_buf to track the usage.
  * It could support changing the name of the dma-buf if the same
  * piece of memory is used for multiple purpose between different devices.
  *
  * @dmabuf: [in]     dmabuf buffer that will be renamed.
  * @buf:    [in]     A piece of userspace memory that contains the name of
  *                   the dma-buf.
  *
  * Returns 0 on success. If the dma-buf buffer is already attached to
  * devices, return -EBUSY.
  *
  */
 static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
 {
     char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
 
     if (IS_ERR(name))
         return PTR_ERR(name);
 
     spin_lock(&dmabuf->name_lock);
     kfree(dmabuf->name);
     dmabuf->name = name;
     spin_unlock(&dmabuf->name_lock);
 
     return 0;
 }
 
 #if IS_ENABLED(CONFIG_SYNC_FILE)
 static long dma_buf_export_sync_file(struct dma_buf *dmabuf,
                      void __user *user_data)
 {
     struct dma_buf_export_sync_file arg;
     enum dma_resv_usage usage;
     struct dma_fence *fence = NULL;
     struct sync_file *sync_file;
     int fd, ret;
 
     if (copy_from_user(&arg, user_data, sizeof(arg)))
         return -EFAULT;
 
     if (arg.flags & ~DMA_BUF_SYNC_RW)
         return -EINVAL;
 
     if ((arg.flags & DMA_BUF_SYNC_RW) == 0)
         return -EINVAL;
 
     fd = get_unused_fd_flags(O_CLOEXEC);
     if (fd < 0)
         return fd;
 
     usage = dma_resv_usage_rw(arg.flags & DMA_BUF_SYNC_WRITE);
     ret = dma_resv_get_singleton(dmabuf->resv, usage, &fence);
     if (ret)
         goto err_put_fd;
 
     if (!fence)
         fence = dma_fence_get_stub();
 
     sync_file = sync_file_create(fence);
 
     dma_fence_put(fence);
 
     if (!sync_file) {
         ret = -ENOMEM;
         goto err_put_fd;
     }
 
     arg.fd = fd;
     if (copy_to_user(user_data, &arg, sizeof(arg))) {
         ret = -EFAULT;
         goto err_put_file;
     }
 
     fd_install(fd, sync_file->file);
 
     return 0;
 
 err_put_file:
     fput(sync_file->file);
 err_put_fd:
     put_unused_fd(fd);
     return ret;
 }
 
 static long dma_buf_import_sync_file(struct dma_buf *dmabuf,
                      const void __user *user_data)
 {
     struct dma_buf_import_sync_file arg;
     struct dma_fence *fence;
     enum dma_resv_usage usage;
     int ret = 0;
 
     if (copy_from_user(&arg, user_data, sizeof(arg)))
         return -EFAULT;
 
     if (arg.flags & ~DMA_BUF_SYNC_RW)
         return -EINVAL;
 
     if ((arg.flags & DMA_BUF_SYNC_RW) == 0)
         return -EINVAL;
 
     fence = sync_file_get_fence(arg.fd);
     if (!fence)
         return -EINVAL;
 
     usage = (arg.flags & DMA_BUF_SYNC_WRITE) ? DMA_RESV_USAGE_WRITE :
                            DMA_RESV_USAGE_READ;
 
     dma_resv_lock(dmabuf->resv, NULL);
 
     ret = dma_resv_reserve_fences(dmabuf->resv, 1);
     if (!ret)
         dma_resv_add_fence(dmabuf->resv, fence, usage);
 
     dma_resv_unlock(dmabuf->resv);
 
     dma_fence_put(fence);
 
     return ret;
 }
 #endif
 
 static long dma_buf_ioctl(struct file *file,
               unsigned int cmd, unsigned long arg)
 {
     struct dma_buf *dmabuf;
     struct dma_buf_sync sync;
     enum dma_data_direction direction;
     int ret;
 
     dmabuf = file->private_data;
 
     switch (cmd) {
     case DMA_BUF_IOCTL_SYNC:
         if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
             return -EFAULT;
 
         if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
             return -EINVAL;
 
         switch (sync.flags & DMA_BUF_SYNC_RW) {
         case DMA_BUF_SYNC_READ:
             direction = DMA_FROM_DEVICE;
             break;
         case DMA_BUF_SYNC_WRITE:
             direction = DMA_TO_DEVICE;
             break;
         case DMA_BUF_SYNC_RW:
             direction = DMA_BIDIRECTIONAL;
             break;
         default:
             return -EINVAL;
         }
 
         if (sync.flags & DMA_BUF_SYNC_END)
             ret = dma_buf_end_cpu_access(dmabuf, direction);
         else
             ret = dma_buf_begin_cpu_access(dmabuf, direction);
 
         return ret;
 
     case DMA_BUF_SET_NAME_A:
     case DMA_BUF_SET_NAME_B:
         return dma_buf_set_name(dmabuf, (const char __user *)arg);
 
 #if IS_ENABLED(CONFIG_SYNC_FILE)
     case DMA_BUF_IOCTL_EXPORT_SYNC_FILE:
         return dma_buf_export_sync_file(dmabuf, (void __user *)arg);
     case DMA_BUF_IOCTL_IMPORT_SYNC_FILE:
         return dma_buf_import_sync_file(dmabuf, (const void __user *)arg);
 #endif
 
     default:
         return -ENOTTY;
     }
 }
 
 static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file)
 {
     struct dma_buf *dmabuf = file->private_data;
 
     seq_printf(m, "size:\t%zu\n", dmabuf->size);
     /* Don't count the temporary reference taken inside procfs seq_show */
     seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1);
     seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name);
     spin_lock(&dmabuf->name_lock);
     if (dmabuf->name)
         seq_printf(m, "name:\t%s\n", dmabuf->name);
     spin_unlock(&dmabuf->name_lock);
 }
 
 static const struct file_operations dma_buf_fops = {
     .release    = dma_buf_file_release,
     .mmap       = dma_buf_mmap_internal,
     .llseek     = dma_buf_llseek,
     .poll       = dma_buf_poll,
     .unlocked_ioctl = dma_buf_ioctl,
     .compat_ioctl   = compat_ptr_ioctl,
     .show_fdinfo    = dma_buf_show_fdinfo,
 };
 
 /*
  * 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;
 }
 
 static struct file *dma_buf_getfile(struct dma_buf *dmabuf, int flags)
 {
     static atomic64_t dmabuf_inode = ATOMIC64_INIT(0);
     struct file *file;
     struct inode *inode = alloc_anon_inode(dma_buf_mnt->mnt_sb);
 
     if (IS_ERR(inode))
         return ERR_CAST(inode);
 
     inode->i_size = dmabuf->size;
     inode_set_bytes(inode, dmabuf->size);
 
     /*
      * The ->i_ino acquired from get_next_ino() is not unique thus
      * not suitable for using it as dentry name by dmabuf stats.
      * Override ->i_ino with the unique and dmabuffs specific
      * value.
      */
     inode->i_ino = atomic64_add_return(1, &dmabuf_inode);
     file = alloc_file_pseudo(inode, dma_buf_mnt, "dmabuf",
                  flags, &dma_buf_fops);
     if (IS_ERR(file))
         goto err_alloc_file;
     file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
     file->private_data = dmabuf;
     file->f_path.dentry->d_fsdata = dmabuf;
 
     return file;
 
 err_alloc_file:
     iput(inode);
     return file;
 }
 
 /**
  * DOC: dma buf device access
  *
  * For device DMA access to a shared DMA buffer the usual sequence of operations
  * is fairly simple:
  *
  * 1. The exporter defines his exporter instance using
  *    DEFINE_DMA_BUF_EXPORT_INFO() and calls dma_buf_export() to wrap a private
  *    buffer object into a &dma_buf. It then exports that &dma_buf to userspace
  *    as a file descriptor by calling dma_buf_fd().
  *
  * 2. Userspace passes this file-descriptors to all drivers it wants this buffer
  *    to share with: First the file descriptor is converted to a &dma_buf using
  *    dma_buf_get(). Then the buffer is attached to the device using
  *    dma_buf_attach().
  *
  *    Up to this stage the exporter is still free to migrate or reallocate the
  *    backing storage.
  *
  * 3. Once the buffer is attached to all devices userspace can initiate DMA
  *    access to the shared buffer. In the kernel this is done by calling
  *    dma_buf_map_attachment() and dma_buf_unmap_attachment().
  *
  * 4. Once a driver is done with a shared buffer it needs to call
  *    dma_buf_detach() (after cleaning up any mappings) and then release the
  *    reference acquired with dma_buf_get() by calling dma_buf_put().
  *
  * For the detailed semantics exporters are expected to implement see
  * &dma_buf_ops.
  */
 
 /**
  * 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 struct dma_buf object, which wraps the
  * supplied private data and operations for struct dma_buf_ops. On either
  * missing ops, or error in allocating struct dma_buf, will return negative
  * error.
  *
  * For most cases the easiest way to create @exp_info is through the
  * %DEFINE_DMA_BUF_EXPORT_INFO macro.
  */
 struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 {
     struct dma_buf *dmabuf;
     struct dma_resv *resv = exp_info->resv;
     struct file *file;
     size_t alloc_size = sizeof(struct dma_buf);
     int ret;
 
     if (!exp_info->resv)
         alloc_size += sizeof(struct dma_resv);
     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)) {
         return ERR_PTR(-EINVAL);
     }
 
     if (WARN_ON(exp_info->ops->cache_sgt_mapping &&
             (exp_info->ops->pin || exp_info->ops->unpin)))
         return ERR_PTR(-EINVAL);
 
     if (WARN_ON(!exp_info->ops->pin != !exp_info->ops->unpin))
         return ERR_PTR(-EINVAL);
 
     if (!try_module_get(exp_info->owner))
         return ERR_PTR(-ENOENT);
 
     dmabuf = kzalloc(alloc_size, GFP_KERNEL);
     if (!dmabuf) {
         ret = -ENOMEM;
         goto err_module;
     }
 
     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;
     spin_lock_init(&dmabuf->name_lock);
     init_waitqueue_head(&dmabuf->poll);
     dmabuf->cb_in.poll = dmabuf->cb_out.poll = &dmabuf->poll;
     dmabuf->cb_in.active = dmabuf->cb_out.active = 0;
 
     if (!resv) {
         resv = (struct dma_resv *)&dmabuf[1];
         dma_resv_init(resv);
     }
     dmabuf->resv = resv;
 
     file = dma_buf_getfile(dmabuf, exp_info->flags);
     if (IS_ERR(file)) {
         ret = PTR_ERR(file);
         goto err_dmabuf;
     }
 
     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);
 
     ret = dma_buf_stats_setup(dmabuf);
     if (ret)
         goto err_sysfs;
 
     return dmabuf;
 
 err_sysfs:
     /*
      * Set file->f_path.dentry->d_fsdata to NULL so that when
      * dma_buf_release() gets invoked by dentry_ops, it exits
      * early before calling the release() dma_buf op.
      */
     file->f_path.dentry->d_fsdata = NULL;
     fput(file);
 err_dmabuf:
     kfree(dmabuf);
 err_module:
     module_put(exp_info->owner);
     return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_export, DMA_BUF);
 
 /**
  * dma_buf_fd - returns a file descriptor for the given struct 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_NS_GPL(dma_buf_fd, DMA_BUF);
 
 /**
  * dma_buf_get - returns the struct dma_buf related to an fd
  * @fd: [in]    fd associated with the struct dma_buf to be returned
  *
  * On success, returns the struct dma_buf 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_NS_GPL(dma_buf_get, DMA_BUF);
 
 /**
  * dma_buf_put - decreases refcount of the buffer
  * @dmabuf: [in]    buffer to reduce refcount of
  *
  * Uses file's refcounting done implicitly by fput().
  *
  * If, as a result of this call, the refcount becomes 0, the 'release' file
  * operation related to this fd is called. It calls &dma_buf_ops.release vfunc
  * in turn, and frees the memory allocated for dmabuf when exported.
  */
 void dma_buf_put(struct dma_buf *dmabuf)
 {
     if (WARN_ON(!dmabuf || !dmabuf->file))
         return;
 
     fput(dmabuf->file);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_put, DMA_BUF);
 
 static void mangle_sg_table(struct sg_table *sg_table)
 {
 #ifdef CONFIG_DMABUF_DEBUG
     int i;
     struct scatterlist *sg;
 
     /* To catch abuse of the underlying struct page by importers mix
      * up the bits, but take care to preserve the low SG_ bits to
      * not corrupt the sgt. The mixing is undone in __unmap_dma_buf
      * before passing the sgt back to the exporter. */
     for_each_sgtable_sg(sg_table, sg, i)
         sg->page_link ^= ~0xffUL;
 #endif
 
 }
 static struct sg_table * __map_dma_buf(struct dma_buf_attachment *attach,
                        enum dma_data_direction direction)
 {
     struct sg_table *sg_table;
     signed long ret;
 
     sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
     if (IS_ERR_OR_NULL(sg_table))
         return sg_table;
 
     if (!dma_buf_attachment_is_dynamic(attach)) {
         ret = dma_resv_wait_timeout(attach->dmabuf->resv,
                         DMA_RESV_USAGE_KERNEL, true,
                         MAX_SCHEDULE_TIMEOUT);
         if (ret < 0) {
             attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
                                direction);
             return ERR_PTR(ret);
         }
     }
 
     mangle_sg_table(sg_table);
     return sg_table;
 }
 
 /**
  * dma_buf_dynamic_attach - Add the device to dma_buf's attachments list
  * @dmabuf:     [in]    buffer to attach device to.
  * @dev:        [in]    device to be attached.
  * @importer_ops:   [in]    importer operations for the attachment
  * @importer_priv:  [in]    importer private pointer for the attachment
  *
  * Returns struct dma_buf_attachment pointer for this attachment. Attachments
  * must be cleaned up by calling dma_buf_detach().
  *
  * Optionally this calls &dma_buf_ops.attach to allow device-specific attach
  * functionality.
  *
  * Returns:
  *
  * A pointer to newly created &dma_buf_attachment on success, or a negative
  * error code wrapped into a pointer on failure.
  *
  * Note that this can fail if the backing storage of @dmabuf is in a place not
  * accessible to @dev, and cannot be moved to a more suitable place. This is
  * indicated with the error code -EBUSY.
  */
 struct dma_buf_attachment *
 dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
                const struct dma_buf_attach_ops *importer_ops,
                void *importer_priv)
 {
     struct dma_buf_attachment *attach;
     int ret;
 
     if (WARN_ON(!dmabuf || !dev))
         return ERR_PTR(-EINVAL);
 
     if (WARN_ON(importer_ops && !importer_ops->move_notify))
         return ERR_PTR(-EINVAL);
 
     attach = kzalloc(sizeof(*attach), GFP_KERNEL);
     if (!attach)
         return ERR_PTR(-ENOMEM);
 
     attach->dev = dev;
     attach->dmabuf = dmabuf;
     if (importer_ops)
         attach->peer2peer = importer_ops->allow_peer2peer;
     attach->importer_ops = importer_ops;
     attach->importer_priv = importer_priv;
 
     if (dmabuf->ops->attach) {
         ret = dmabuf->ops->attach(dmabuf, attach);
         if (ret)
             goto err_attach;
     }
     dma_resv_lock(dmabuf->resv, NULL);
     list_add(&attach->node, &dmabuf->attachments);
     dma_resv_unlock(dmabuf->resv);
 
     /* When either the importer or the exporter can't handle dynamic
      * mappings we cache the mapping here to avoid issues with the
      * reservation object lock.
      */
     if (dma_buf_attachment_is_dynamic(attach) !=
         dma_buf_is_dynamic(dmabuf)) {
         struct sg_table *sgt;
 
         if (dma_buf_is_dynamic(attach->dmabuf)) {
             dma_resv_lock(attach->dmabuf->resv, NULL);
             ret = dmabuf->ops->pin(attach);
             if (ret)
                 goto err_unlock;
         }
 
         sgt = __map_dma_buf(attach, DMA_BIDIRECTIONAL);
         if (!sgt)
             sgt = ERR_PTR(-ENOMEM);
         if (IS_ERR(sgt)) {
             ret = PTR_ERR(sgt);
             goto err_unpin;
         }
         if (dma_buf_is_dynamic(attach->dmabuf))
             dma_resv_unlock(attach->dmabuf->resv);
         attach->sgt = sgt;
         attach->dir = DMA_BIDIRECTIONAL;
     }
 
     return attach;
 
 err_attach:
     kfree(attach);
     return ERR_PTR(ret);
 
 err_unpin:
     if (dma_buf_is_dynamic(attach->dmabuf))
         dmabuf->ops->unpin(attach);
 
 err_unlock:
     if (dma_buf_is_dynamic(attach->dmabuf))
         dma_resv_unlock(attach->dmabuf->resv);
 
     dma_buf_detach(dmabuf, attach);
     return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_dynamic_attach, DMA_BUF);
 
 /**
  * dma_buf_attach - Wrapper for dma_buf_dynamic_attach
  * @dmabuf: [in]    buffer to attach device to.
  * @dev:    [in]    device to be attached.
  *
  * Wrapper to call dma_buf_dynamic_attach() for drivers which still use a static
  * mapping.
  */
 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
                       struct device *dev)
 {
     return dma_buf_dynamic_attach(dmabuf, dev, NULL, NULL);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_attach, DMA_BUF);
 
 static void __unmap_dma_buf(struct dma_buf_attachment *attach,
                 struct sg_table *sg_table,
                 enum dma_data_direction direction)
 {
     /* uses XOR, hence this unmangles */
     mangle_sg_table(sg_table);
 
     attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
 }
 
 /**
  * dma_buf_detach - Remove the given attachment from dmabuf's attachments list
  * @dmabuf: [in]    buffer to detach from.
  * @attach: [in]    attachment to be detached; is free'd after this call.
  *
  * Clean up a device attachment obtained by calling dma_buf_attach().
  *
  * Optionally this calls &dma_buf_ops.detach for device-specific detach.
  */
 void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 {
     if (WARN_ON(!dmabuf || !attach))
         return;
 
     if (attach->sgt) {
         if (dma_buf_is_dynamic(attach->dmabuf))
             dma_resv_lock(attach->dmabuf->resv, NULL);
 
         __unmap_dma_buf(attach, attach->sgt, attach->dir);
 
         if (dma_buf_is_dynamic(attach->dmabuf)) {
             dmabuf->ops->unpin(attach);
             dma_resv_unlock(attach->dmabuf->resv);
         }
     }
 
     dma_resv_lock(dmabuf->resv, NULL);
     list_del(&attach->node);
     dma_resv_unlock(dmabuf->resv);
     if (dmabuf->ops->detach)
         dmabuf->ops->detach(dmabuf, attach);
 
     kfree(attach);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_detach, DMA_BUF);
 
 /**
  * dma_buf_pin - Lock down the DMA-buf
  * @attach: [in]    attachment which should be pinned
  *
  * Only dynamic importers (who set up @attach with dma_buf_dynamic_attach()) may
  * call this, and only for limited use cases like scanout and not for temporary
  * pin operations. It is not permitted to allow userspace to pin arbitrary
  * amounts of buffers through this interface.
  *
  * Buffers must be unpinned by calling dma_buf_unpin().
  *
  * Returns:
  * 0 on success, negative error code on failure.
  */
 int dma_buf_pin(struct dma_buf_attachment *attach)
 {
     struct dma_buf *dmabuf = attach->dmabuf;
     int ret = 0;
 
     WARN_ON(!dma_buf_attachment_is_dynamic(attach));
 
     dma_resv_assert_held(dmabuf->resv);
 
     if (dmabuf->ops->pin)
         ret = dmabuf->ops->pin(attach);
 
     return ret;
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_pin, DMA_BUF);
 
 /**
  * dma_buf_unpin - Unpin a DMA-buf
  * @attach: [in]    attachment which should be unpinned
  *
  * This unpins a buffer pinned by dma_buf_pin() and allows the exporter to move
  * any mapping of @attach again and inform the importer through
  * &dma_buf_attach_ops.move_notify.
  */
 void dma_buf_unpin(struct dma_buf_attachment *attach)
 {
     struct dma_buf *dmabuf = attach->dmabuf;
 
     WARN_ON(!dma_buf_attachment_is_dynamic(attach));
 
     dma_resv_assert_held(dmabuf->resv);
 
     if (dmabuf->ops->unpin)
         dmabuf->ops->unpin(attach);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_unpin, DMA_BUF);
 
 /**
  * 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. May return -EINTR if it is interrupted by a signal.
  *
  * On success, the DMA addresses and lengths in the returned scatterlist are
  * PAGE_SIZE aligned.
  *
  * A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that
  * the underlying backing storage is pinned for as long as a mapping exists,
  * therefore users/importers should not hold onto a mapping for undue amounts of
  * time.
  *
  * Important: Dynamic importers must wait for the exclusive fence of the struct
  * dma_resv attached to the DMA-BUF first.
  */
 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
                     enum dma_data_direction direction)
 {
     struct sg_table *sg_table;
     int r;
 
     might_sleep();
 
     if (WARN_ON(!attach || !attach->dmabuf))
         return ERR_PTR(-EINVAL);
 
     if (dma_buf_attachment_is_dynamic(attach))
         dma_resv_assert_held(attach->dmabuf->resv);
 
     if (attach->sgt) {
         /*
          * Two mappings with different directions for the same
          * attachment are not allowed.
          */
         if (attach->dir != direction &&
             attach->dir != DMA_BIDIRECTIONAL)
             return ERR_PTR(-EBUSY);
 
         return attach->sgt;
     }
 
     if (dma_buf_is_dynamic(attach->dmabuf)) {
         dma_resv_assert_held(attach->dmabuf->resv);
         if (!IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY)) {
             r = attach->dmabuf->ops->pin(attach);
             if (r)
                 return ERR_PTR(r);
         }
     }
 
     sg_table = __map_dma_buf(attach, direction);
     if (!sg_table)
         sg_table = ERR_PTR(-ENOMEM);
 
     if (IS_ERR(sg_table) && dma_buf_is_dynamic(attach->dmabuf) &&
          !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
         attach->dmabuf->ops->unpin(attach);
 
     if (!IS_ERR(sg_table) && attach->dmabuf->ops->cache_sgt_mapping) {
         attach->sgt = sg_table;
         attach->dir = direction;
     }
 
 #ifdef CONFIG_DMA_API_DEBUG
     if (!IS_ERR(sg_table)) {
         struct scatterlist *sg;
         u64 addr;
         int len;
         int i;
 
         for_each_sgtable_dma_sg(sg_table, sg, i) {
             addr = sg_dma_address(sg);
             len = sg_dma_len(sg);
             if (!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(len)) {
                 pr_debug("%s: addr %llx or len %x is not page aligned!\n",
                      __func__, addr, len);
             }
         }
     }
 #endif /* CONFIG_DMA_API_DEBUG */
     return sg_table;
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment, DMA_BUF);
 
 /**
  * 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
  *
  * This unmaps a DMA mapping for @attached obtained by dma_buf_map_attachment().
  */
 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;
 
     if (dma_buf_attachment_is_dynamic(attach))
         dma_resv_assert_held(attach->dmabuf->resv);
 
     if (attach->sgt == sg_table)
         return;
 
     if (dma_buf_is_dynamic(attach->dmabuf))
         dma_resv_assert_held(attach->dmabuf->resv);
 
     __unmap_dma_buf(attach, sg_table, direction);
 
     if (dma_buf_is_dynamic(attach->dmabuf) &&
         !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
         dma_buf_unpin(attach);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment, DMA_BUF);
 
 /**
  * dma_buf_move_notify - notify attachments that DMA-buf is moving
  *
  * @dmabuf: [in]    buffer which is moving
  *
  * Informs all attachmenst that they need to destroy and recreated all their
  * mappings.
  */
 void dma_buf_move_notify(struct dma_buf *dmabuf)
 {
     struct dma_buf_attachment *attach;
 
     dma_resv_assert_held(dmabuf->resv);
 
     list_for_each_entry(attach, &dmabuf->attachments, node)
         if (attach->importer_ops)
             attach->importer_ops->move_notify(attach);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_move_notify, DMA_BUF);
 
 /**
  * DOC: cpu access
  *
  * There are mutliple reasons for supporting CPU access to a dma buffer object:
  *
  * - Fallback operations in the kernel, for example when a device is connected
  *   over USB and the kernel needs to shuffle the data around first before
  *   sending it away. Cache coherency is handled by braketing any transactions
  *   with calls to dma_buf_begin_cpu_access() and dma_buf_end_cpu_access()
  *   access.
  *
  *   Since for most kernel internal dma-buf accesses need the entire buffer, a
  *   vmap interface is introduced. Note that on very old 32-bit architectures
  *   vmalloc space might be limited and result in vmap calls failing.
  *
  *   Interfaces::
  *
  *      void \*dma_buf_vmap(struct dma_buf \*dmabuf, struct iosys_map \*map)
  *      void dma_buf_vunmap(struct dma_buf \*dmabuf, struct iosys_map \*map)
  *
  *   The vmap call can fail if there is no vmap support in the exporter, or if
  *   it runs out of vmalloc space. Note that the dma-buf layer keeps a reference
  *   count for all vmap access and calls down into the exporter's vmap function
  *   only when no vmapping exists, and only unmaps it once. Protection against
  *   concurrent vmap/vunmap calls is provided by taking the &dma_buf.lock mutex.
  *
  * - For full compatibility on the importer side with existing userspace
  *   interfaces, which might already support mmap'ing buffers. This is needed in
  *   many processing pipelines (e.g. feeding a software rendered image into a
  *   hardware pipeline, thumbnail creation, snapshots, ...). Also, Android's ION
  *   framework already supported this and for DMA buffer file descriptors to
  *   replace ION buffers mmap support was needed.
  *
  *   There is no special interfaces, userspace simply calls mmap on the dma-buf
  *   fd. But like for CPU access there's a need to braket the actual access,
  *   which is handled by the ioctl (DMA_BUF_IOCTL_SYNC). Note that
  *   DMA_BUF_IOCTL_SYNC can fail with -EAGAIN or -EINTR, in which case it must
  *   be restarted.
  *
  *   Some systems might need some sort of cache coherency management e.g. when
  *   CPU and GPU domains are being accessed through dma-buf at the same time.
  *   To circumvent this problem there are begin/end coherency markers, that
  *   forward directly to existing dma-buf device drivers vfunc hooks. Userspace
  *   can make use of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The
  *   sequence would be used like following:
  *
  *     - mmap dma-buf fd
  *     - for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
  *       to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
  *       want (with the new data being consumed by say the GPU or the scanout
  *       device)
  *     - munmap once you don't need the buffer any more
  *
  *    For correctness and optimal performance, it is always required to use
  *    SYNC_START and SYNC_END before and after, respectively, when accessing the
  *    mapped address. Userspace cannot rely on coherent access, even when there
  *    are systems where it just works without calling these ioctls.
  *
  * - And as a CPU fallback in userspace processing pipelines.
  *
  *   Similar to the motivation for kernel cpu access it is again important that
  *   the userspace code of a given importing subsystem can use the same
  *   interfaces with a imported dma-buf buffer object as with a native buffer
  *   object. This is especially important for drm where the userspace part of
  *   contemporary OpenGL, X, and other drivers is huge, and reworking them to
  *   use a different way to mmap a buffer rather invasive.
  *
  *   The assumption in the current dma-buf interfaces is that redirecting the
  *   initial mmap is all that's needed. A survey of some of the existing
  *   subsystems shows that no driver seems to do any nefarious thing like
  *   syncing up with outstanding asynchronous processing on the device or
  *   allocating special resources at fault time. So hopefully this is good
  *   enough, since adding interfaces to intercept pagefaults and allow pte
  *   shootdowns would increase the complexity quite a bit.
  *
  *   Interface::
  *
  *      int dma_buf_mmap(struct dma_buf \*, struct vm_area_struct \*,
  *             unsigned long);
  *
  *   If the importing subsystem simply provides a special-purpose mmap call to
  *   set up a mapping in userspace, calling do_mmap with &dma_buf.file will
  *   equally achieve that for a dma-buf object.
  */
 
 static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
                       enum dma_data_direction direction)
 {
     bool write = (direction == DMA_BIDIRECTIONAL ||
               direction == DMA_TO_DEVICE);
     struct dma_resv *resv = dmabuf->resv;
     long ret;
 
     /* Wait on any implicit rendering fences */
     ret = dma_resv_wait_timeout(resv, dma_resv_usage_rw(write),
                     true, MAX_SCHEDULE_TIMEOUT);
     if (ret < 0)
         return ret;
 
     return 0;
 }
 
 /**
  * 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.
  *
  * After the cpu access is complete the caller should call
  * dma_buf_end_cpu_access(). Only when cpu access is braketed by both calls is
  * it guaranteed to be coherent with other DMA access.
  *
  * This function will also wait for any DMA transactions tracked through
  * implicit synchronization in &dma_buf.resv. For DMA transactions with explicit
  * synchronization this function will only ensure cache coherency, callers must
  * ensure synchronization with such DMA transactions on their own.
  *
  * 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;
 
     might_lock(&dmabuf->resv->lock.base);
 
     if (dmabuf->ops->begin_cpu_access)
         ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);
 
     /* Ensure that all fences are waited upon - but we first allow
      * the native handler the chance to do so more efficiently if it
      * chooses. A double invocation here will be reasonably cheap no-op.
      */
     if (ret == 0)
         ret = __dma_buf_begin_cpu_access(dmabuf, direction);
 
     return ret;
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_begin_cpu_access, DMA_BUF);
 
 /**
  * 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 terminates CPU access started with dma_buf_begin_cpu_access().
  *
  * Can return negative error values, returns 0 on success.
  */
 int dma_buf_end_cpu_access(struct dma_buf *dmabuf,
                enum dma_data_direction direction)
 {
     int ret = 0;
 
     WARN_ON(!dmabuf);
 
     might_lock(&dmabuf->resv->lock.base);
 
     if (dmabuf->ops->end_cpu_access)
         ret = dmabuf->ops->end_cpu_access(dmabuf, direction);
 
     return ret;
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_end_cpu_access, DMA_BUF);
 
 
 /**
  * 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)
 {
     if (WARN_ON(!dmabuf || !vma))
         return -EINVAL;
 
     /* check if buffer supports mmap */
     if (!dmabuf->ops->mmap)
         return -EINVAL;
 
     /* check for offset overflow */
     if (pgoff + vma_pages(vma) < pgoff)
         return -EOVERFLOW;
 
     /* check for overflowing the buffer's size */
     if (pgoff + vma_pages(vma) >
         dmabuf->size >> PAGE_SHIFT)
         return -EINVAL;
 
     /* readjust the vma */
     vma_set_file(vma, dmabuf->file);
     vma->vm_pgoff = pgoff;
 
     return dmabuf->ops->mmap(dmabuf, vma);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, DMA_BUF);
 
 /**
  * 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
  * @map:    [out]   returns the vmap pointer
  *
  * 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.
  *
  * To ensure coherency users must call dma_buf_begin_cpu_access() and
  * dma_buf_end_cpu_access() around any cpu access performed through this
  * mapping.
  *
  * Returns 0 on success, or a negative errno code otherwise.
  */
 int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
 {
     struct iosys_map ptr;
     int ret = 0;
 
     iosys_map_clear(map);
 
     if (WARN_ON(!dmabuf))
         return -EINVAL;
 
     if (!dmabuf->ops->vmap)
         return -EINVAL;
 
     mutex_lock(&dmabuf->lock);
     if (dmabuf->vmapping_counter) {
         dmabuf->vmapping_counter++;
         BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
         *map = dmabuf->vmap_ptr;
         goto out_unlock;
     }
 
     BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr));
 
     ret = dmabuf->ops->vmap(dmabuf, &ptr);
     if (WARN_ON_ONCE(ret))
         goto out_unlock;
 
     dmabuf->vmap_ptr = ptr;
     dmabuf->vmapping_counter = 1;
 
     *map = dmabuf->vmap_ptr;
 
 out_unlock:
     mutex_unlock(&dmabuf->lock);
     return ret;
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_vmap, DMA_BUF);
 
 /**
  * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
  * @dmabuf: [in]    buffer to vunmap
  * @map:    [in]    vmap pointer to vunmap
  */
 void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
 {
     if (WARN_ON(!dmabuf))
         return;
 
     BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
     BUG_ON(dmabuf->vmapping_counter == 0);
     BUG_ON(!iosys_map_is_equal(&dmabuf->vmap_ptr, map));
 
     mutex_lock(&dmabuf->lock);
     if (--dmabuf->vmapping_counter == 0) {
         if (dmabuf->ops->vunmap)
             dmabuf->ops->vunmap(dmabuf, map);
         iosys_map_clear(&dmabuf->vmap_ptr);
     }
     mutex_unlock(&dmabuf->lock);
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap, DMA_BUF);
 
 #ifdef CONFIG_DEBUG_FS
 static int dma_buf_debug_show(struct seq_file *s, void *unused)
 {
     struct dma_buf *buf_obj;
     struct dma_buf_attachment *attach_obj;
     int count = 0, attach_count;
     size_t size = 0;
     int ret;
 
     ret = mutex_lock_interruptible(&db_list.lock);
 
     if (ret)
         return ret;
 
     seq_puts(s, "\nDma-buf Objects:\n");
     seq_printf(s, "%-8s\t%-8s\t%-8s\t%-8s\texp_name\t%-8s\tname\n",
            "size", "flags", "mode", "count", "ino");
 
     list_for_each_entry(buf_obj, &db_list.head, list_node) {
 
         ret = dma_resv_lock_interruptible(buf_obj->resv, NULL);
         if (ret)
             goto error_unlock;
 
 
         spin_lock(&buf_obj->name_lock);
         seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\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,
                 file_inode(buf_obj->file)->i_ino,
                 buf_obj->name ?: "<none>");
         spin_unlock(&buf_obj->name_lock);
 
         dma_resv_describe(buf_obj->resv, s);
 
         seq_puts(s, "\tAttached Devices:\n");
         attach_count = 0;
 
         list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
             seq_printf(s, "\t%s\n", dev_name(attach_obj->dev));
             attach_count++;
         }
         dma_resv_unlock(buf_obj->resv);
 
         seq_printf(s, "Total %d devices attached\n\n",
                 attach_count);
 
         count++;
         size += buf_obj->size;
     }
 
     seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
 
     mutex_unlock(&db_list.lock);
     return 0;
 
 error_unlock:
     mutex_unlock(&db_list.lock);
     return ret;
 }
 
 DEFINE_SHOW_ATTRIBUTE(dma_buf_debug);
 
 static struct dentry *dma_buf_debugfs_dir;
 
 static int dma_buf_init_debugfs(void)
 {
     struct dentry *d;
     int err = 0;
 
     d = debugfs_create_dir("dma_buf", NULL);
     if (IS_ERR(d))
         return PTR_ERR(d);
 
     dma_buf_debugfs_dir = d;
 
     d = debugfs_create_file("bufinfo", S_IRUGO, dma_buf_debugfs_dir,
                 NULL, &dma_buf_debug_fops);
     if (IS_ERR(d)) {
         pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
         debugfs_remove_recursive(dma_buf_debugfs_dir);
         dma_buf_debugfs_dir = NULL;
         err = PTR_ERR(d);
     }
 
     return err;
 }
 
 static void dma_buf_uninit_debugfs(void)
 {
     debugfs_remove_recursive(dma_buf_debugfs_dir);
 }
 #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)
 {
     int ret;
 
     ret = dma_buf_init_sysfs_statistics();
     if (ret)
         return ret;
 
     dma_buf_mnt = kern_mount(&dma_buf_fs_type);
     if (IS_ERR(dma_buf_mnt))
         return PTR_ERR(dma_buf_mnt);
 
     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();
     kern_unmount(dma_buf_mnt);
     dma_buf_uninit_sysfs_statistics();
 }
 __exitcall(dma_buf_deinit);

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