OSCL-LXR linux-6.0.1/​drivers/​gpu/​drm/​drm_gem.c	Source navigation Diff markup Identifier search General search
	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

 /*
  * Copyright © 2008 Intel Corporation
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice (including the next
  * paragraph) shall be included in all copies or substantial portions of the
  * Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  * IN THE SOFTWARE.
  *
  * Authors:
  *    Eric Anholt <eric@anholt.net>
  *
  */
 
 #include <linux/dma-buf.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/iosys-map.h>
 #include <linux/mem_encrypt.h>
 #include <linux/mm.h>
 #include <linux/mman.h>
 #include <linux/module.h>
 #include <linux/pagemap.h>
 #include <linux/pagevec.h>
 #include <linux/shmem_fs.h>
 #include <linux/slab.h>
 #include <linux/string_helpers.h>
 #include <linux/types.h>
 #include <linux/uaccess.h>
 
 #include <drm/drm.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_file.h>
 #include <drm/drm_gem.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_print.h>
 #include <drm/drm_vma_manager.h>
 
 #include "drm_internal.h"
 
 /** @file drm_gem.c
  *
  * This file provides some of the base ioctls and library routines for
  * the graphics memory manager implemented by each device driver.
  *
  * Because various devices have different requirements in terms of
  * synchronization and migration strategies, implementing that is left up to
  * the driver, and all that the general API provides should be generic --
  * allocating objects, reading/writing data with the cpu, freeing objects.
  * Even there, platform-dependent optimizations for reading/writing data with
  * the CPU mean we'll likely hook those out to driver-specific calls.  However,
  * the DRI2 implementation wants to have at least allocate/mmap be generic.
  *
  * The goal was to have swap-backed object allocation managed through
  * struct file.  However, file descriptors as handles to a struct file have
  * two major failings:
  * - Process limits prevent more than 1024 or so being used at a time by
  *   default.
  * - Inability to allocate high fds will aggravate the X Server's select()
  *   handling, and likely that of many GL client applications as well.
  *
  * This led to a plan of using our own integer IDs (called handles, following
  * DRM terminology) to mimic fds, and implement the fd syscalls we need as
  * ioctls.  The objects themselves will still include the struct file so
  * that we can transition to fds if the required kernel infrastructure shows
  * up at a later date, and as our interface with shmfs for memory allocation.
  */
 
 static void
 drm_gem_init_release(struct drm_device *dev, void *ptr)
 {
     drm_vma_offset_manager_destroy(dev->vma_offset_manager);
 }
 
 /**
  * drm_gem_init - Initialize the GEM device fields
  * @dev: drm_devic structure to initialize
  */
 int
 drm_gem_init(struct drm_device *dev)
 {
     struct drm_vma_offset_manager *vma_offset_manager;
 
     mutex_init(&dev->object_name_lock);
     idr_init_base(&dev->object_name_idr, 1);
 
     vma_offset_manager = drmm_kzalloc(dev, sizeof(*vma_offset_manager),
                       GFP_KERNEL);
     if (!vma_offset_manager) {
         DRM_ERROR("out of memory\n");
         return -ENOMEM;
     }
 
     dev->vma_offset_manager = vma_offset_manager;
     drm_vma_offset_manager_init(vma_offset_manager,
                     DRM_FILE_PAGE_OFFSET_START,
                     DRM_FILE_PAGE_OFFSET_SIZE);
 
     return drmm_add_action(dev, drm_gem_init_release, NULL);
 }
 
 /**
  * drm_gem_object_init - initialize an allocated shmem-backed GEM object
  * @dev: drm_device the object should be initialized for
  * @obj: drm_gem_object to initialize
  * @size: object size
  *
  * Initialize an already allocated GEM object of the specified size with
  * shmfs backing store.
  */
 int drm_gem_object_init(struct drm_device *dev,
             struct drm_gem_object *obj, size_t size)
 {
     struct file *filp;
 
     drm_gem_private_object_init(dev, obj, size);
 
     filp = shmem_file_setup("drm mm object", size, VM_NORESERVE);
     if (IS_ERR(filp))
         return PTR_ERR(filp);
 
     obj->filp = filp;
 
     return 0;
 }
 EXPORT_SYMBOL(drm_gem_object_init);
 
 /**
  * drm_gem_private_object_init - initialize an allocated private GEM object
  * @dev: drm_device the object should be initialized for
  * @obj: drm_gem_object to initialize
  * @size: object size
  *
  * Initialize an already allocated GEM object of the specified size with
  * no GEM provided backing store. Instead the caller is responsible for
  * backing the object and handling it.
  */
 void drm_gem_private_object_init(struct drm_device *dev,
                  struct drm_gem_object *obj, size_t size)
 {
     BUG_ON((size & (PAGE_SIZE - 1)) != 0);
 
     obj->dev = dev;
     obj->filp = NULL;
 
     kref_init(&obj->refcount);
     obj->handle_count = 0;
     obj->size = size;
     dma_resv_init(&obj->_resv);
     if (!obj->resv)
         obj->resv = &obj->_resv;
 
     drm_vma_node_reset(&obj->vma_node);
 }
 EXPORT_SYMBOL(drm_gem_private_object_init);
 
 /**
  * drm_gem_object_handle_free - release resources bound to userspace handles
  * @obj: GEM object to clean up.
  *
  * Called after the last handle to the object has been closed
  *
  * Removes any name for the object. Note that this must be
  * called before drm_gem_object_free or we'll be touching
  * freed memory
  */
 static void drm_gem_object_handle_free(struct drm_gem_object *obj)
 {
     struct drm_device *dev = obj->dev;
 
     /* Remove any name for this object */
     if (obj->name) {
         idr_remove(&dev->object_name_idr, obj->name);
         obj->name = 0;
     }
 }
 
 static void drm_gem_object_exported_dma_buf_free(struct drm_gem_object *obj)
 {
     /* Unbreak the reference cycle if we have an exported dma_buf. */
     if (obj->dma_buf) {
         dma_buf_put(obj->dma_buf);
         obj->dma_buf = NULL;
     }
 }
 
 static void
 drm_gem_object_handle_put_unlocked(struct drm_gem_object *obj)
 {
     struct drm_device *dev = obj->dev;
     bool final = false;
 
     if (WARN_ON(READ_ONCE(obj->handle_count) == 0))
         return;
 
     /*
     * Must bump handle count first as this may be the last
     * ref, in which case the object would disappear before we
     * checked for a name
     */
 
     mutex_lock(&dev->object_name_lock);
     if (--obj->handle_count == 0) {
         drm_gem_object_handle_free(obj);
         drm_gem_object_exported_dma_buf_free(obj);
         final = true;
     }
     mutex_unlock(&dev->object_name_lock);
 
     if (final)
         drm_gem_object_put(obj);
 }
 
 /*
  * Called at device or object close to release the file's
  * handle references on objects.
  */
 static int
 drm_gem_object_release_handle(int id, void *ptr, void *data)
 {
     struct drm_file *file_priv = data;
     struct drm_gem_object *obj = ptr;
 
     if (obj->funcs->close)
         obj->funcs->close(obj, file_priv);
 
     drm_prime_remove_buf_handle(&file_priv->prime, id);
     drm_vma_node_revoke(&obj->vma_node, file_priv);
 
     drm_gem_object_handle_put_unlocked(obj);
 
     return 0;
 }
 
 /**
  * drm_gem_handle_delete - deletes the given file-private handle
  * @filp: drm file-private structure to use for the handle look up
  * @handle: userspace handle to delete
  *
  * Removes the GEM handle from the @filp lookup table which has been added with
  * drm_gem_handle_create(). If this is the last handle also cleans up linked
  * resources like GEM names.
  */
 int
 drm_gem_handle_delete(struct drm_file *filp, u32 handle)
 {
     struct drm_gem_object *obj;
 
     spin_lock(&filp->table_lock);
 
     /* Check if we currently have a reference on the object */
     obj = idr_replace(&filp->object_idr, NULL, handle);
     spin_unlock(&filp->table_lock);
     if (IS_ERR_OR_NULL(obj))
         return -EINVAL;
 
     /* Release driver's reference and decrement refcount. */
     drm_gem_object_release_handle(handle, obj, filp);
 
     /* And finally make the handle available for future allocations. */
     spin_lock(&filp->table_lock);
     idr_remove(&filp->object_idr, handle);
     spin_unlock(&filp->table_lock);
 
     return 0;
 }
 EXPORT_SYMBOL(drm_gem_handle_delete);
 
 /**
  * drm_gem_dumb_map_offset - return the fake mmap offset for a gem object
  * @file: drm file-private structure containing the gem object
  * @dev: corresponding drm_device
  * @handle: gem object handle
  * @offset: return location for the fake mmap offset
  *
  * This implements the &drm_driver.dumb_map_offset kms driver callback for
  * drivers which use gem to manage their backing storage.
  *
  * Returns:
  * 0 on success or a negative error code on failure.
  */
 int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
                 u32 handle, u64 *offset)
 {
     struct drm_gem_object *obj;
     int ret;
 
     obj = drm_gem_object_lookup(file, handle);
     if (!obj)
         return -ENOENT;
 
     /* Don't allow imported objects to be mapped */
     if (obj->import_attach) {
         ret = -EINVAL;
         goto out;
     }
 
     ret = drm_gem_create_mmap_offset(obj);
     if (ret)
         goto out;
 
     *offset = drm_vma_node_offset_addr(&obj->vma_node);
 out:
     drm_gem_object_put(obj);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(drm_gem_dumb_map_offset);
 
 int drm_gem_dumb_destroy(struct drm_file *file,
              struct drm_device *dev,
              u32 handle)
 {
     return drm_gem_handle_delete(file, handle);
 }
 
 /**
  * drm_gem_handle_create_tail - internal functions to create a handle
  * @file_priv: drm file-private structure to register the handle for
  * @obj: object to register
  * @handlep: pointer to return the created handle to the caller
  *
  * This expects the &drm_device.object_name_lock to be held already and will
  * drop it before returning. Used to avoid races in establishing new handles
  * when importing an object from either an flink name or a dma-buf.
  *
  * Handles must be release again through drm_gem_handle_delete(). This is done
  * when userspace closes @file_priv for all attached handles, or through the
  * GEM_CLOSE ioctl for individual handles.
  */
 int
 drm_gem_handle_create_tail(struct drm_file *file_priv,
                struct drm_gem_object *obj,
                u32 *handlep)
 {
     struct drm_device *dev = obj->dev;
     u32 handle;
     int ret;
 
     WARN_ON(!mutex_is_locked(&dev->object_name_lock));
     if (obj->handle_count++ == 0)
         drm_gem_object_get(obj);
 
     /*
      * Get the user-visible handle using idr.  Preload and perform
      * allocation under our spinlock.
      */
     idr_preload(GFP_KERNEL);
     spin_lock(&file_priv->table_lock);
 
     ret = idr_alloc(&file_priv->object_idr, obj, 1, 0, GFP_NOWAIT);
 
     spin_unlock(&file_priv->table_lock);
     idr_preload_end();
 
     mutex_unlock(&dev->object_name_lock);
     if (ret < 0)
         goto err_unref;
 
     handle = ret;
 
     ret = drm_vma_node_allow(&obj->vma_node, file_priv);
     if (ret)
         goto err_remove;
 
     if (obj->funcs->open) {
         ret = obj->funcs->open(obj, file_priv);
         if (ret)
             goto err_revoke;
     }
 
     *handlep = handle;
     return 0;
 
 err_revoke:
     drm_vma_node_revoke(&obj->vma_node, file_priv);
 err_remove:
     spin_lock(&file_priv->table_lock);
     idr_remove(&file_priv->object_idr, handle);
     spin_unlock(&file_priv->table_lock);
 err_unref:
     drm_gem_object_handle_put_unlocked(obj);
     return ret;
 }
 
 /**
  * drm_gem_handle_create - create a gem handle for an object
  * @file_priv: drm file-private structure to register the handle for
  * @obj: object to register
  * @handlep: pointer to return the created handle to the caller
  *
  * Create a handle for this object. This adds a handle reference to the object,
  * which includes a regular reference count. Callers will likely want to
  * dereference the object afterwards.
  *
  * Since this publishes @obj to userspace it must be fully set up by this point,
  * drivers must call this last in their buffer object creation callbacks.
  */
 int drm_gem_handle_create(struct drm_file *file_priv,
               struct drm_gem_object *obj,
               u32 *handlep)
 {
     mutex_lock(&obj->dev->object_name_lock);
 
     return drm_gem_handle_create_tail(file_priv, obj, handlep);
 }
 EXPORT_SYMBOL(drm_gem_handle_create);
 
 
 /**
  * drm_gem_free_mmap_offset - release a fake mmap offset for an object
  * @obj: obj in question
  *
  * This routine frees fake offsets allocated by drm_gem_create_mmap_offset().
  *
  * Note that drm_gem_object_release() already calls this function, so drivers
  * don't have to take care of releasing the mmap offset themselves when freeing
  * the GEM object.
  */
 void
 drm_gem_free_mmap_offset(struct drm_gem_object *obj)
 {
     struct drm_device *dev = obj->dev;
 
     drm_vma_offset_remove(dev->vma_offset_manager, &obj->vma_node);
 }
 EXPORT_SYMBOL(drm_gem_free_mmap_offset);
 
 /**
  * drm_gem_create_mmap_offset_size - create a fake mmap offset for an object
  * @obj: obj in question
  * @size: the virtual size
  *
  * GEM memory mapping works by handing back to userspace a fake mmap offset
  * it can use in a subsequent mmap(2) call.  The DRM core code then looks
  * up the object based on the offset and sets up the various memory mapping
  * structures.
  *
  * This routine allocates and attaches a fake offset for @obj, in cases where
  * the virtual size differs from the physical size (ie. &drm_gem_object.size).
  * Otherwise just use drm_gem_create_mmap_offset().
  *
  * This function is idempotent and handles an already allocated mmap offset
  * transparently. Drivers do not need to check for this case.
  */
 int
 drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size)
 {
     struct drm_device *dev = obj->dev;
 
     return drm_vma_offset_add(dev->vma_offset_manager, &obj->vma_node,
                   size / PAGE_SIZE);
 }
 EXPORT_SYMBOL(drm_gem_create_mmap_offset_size);
 
 /**
  * drm_gem_create_mmap_offset - create a fake mmap offset for an object
  * @obj: obj in question
  *
  * GEM memory mapping works by handing back to userspace a fake mmap offset
  * it can use in a subsequent mmap(2) call.  The DRM core code then looks
  * up the object based on the offset and sets up the various memory mapping
  * structures.
  *
  * This routine allocates and attaches a fake offset for @obj.
  *
  * Drivers can call drm_gem_free_mmap_offset() before freeing @obj to release
  * the fake offset again.
  */
 int drm_gem_create_mmap_offset(struct drm_gem_object *obj)
 {
     return drm_gem_create_mmap_offset_size(obj, obj->size);
 }
 EXPORT_SYMBOL(drm_gem_create_mmap_offset);
 
 /*
  * Move pages to appropriate lru and release the pagevec, decrementing the
  * ref count of those pages.
  */
 static void drm_gem_check_release_pagevec(struct pagevec *pvec)
 {
     check_move_unevictable_pages(pvec);
     __pagevec_release(pvec);
     cond_resched();
 }
 
 /**
  * drm_gem_get_pages - helper to allocate backing pages for a GEM object
  * from shmem
  * @obj: obj in question
  *
  * This reads the page-array of the shmem-backing storage of the given gem
  * object. An array of pages is returned. If a page is not allocated or
  * swapped-out, this will allocate/swap-in the required pages. Note that the
  * whole object is covered by the page-array and pinned in memory.
  *
  * Use drm_gem_put_pages() to release the array and unpin all pages.
  *
  * This uses the GFP-mask set on the shmem-mapping (see mapping_set_gfp_mask()).
  * If you require other GFP-masks, you have to do those allocations yourself.
  *
  * Note that you are not allowed to change gfp-zones during runtime. That is,
  * shmem_read_mapping_page_gfp() must be called with the same gfp_zone(gfp) as
  * set during initialization. If you have special zone constraints, set them
  * after drm_gem_object_init() via mapping_set_gfp_mask(). shmem-core takes care
  * to keep pages in the required zone during swap-in.
  *
  * This function is only valid on objects initialized with
  * drm_gem_object_init(), but not for those initialized with
  * drm_gem_private_object_init() only.
  */
 struct page **drm_gem_get_pages(struct drm_gem_object *obj)
 {
     struct address_space *mapping;
     struct page *p, **pages;
     struct pagevec pvec;
     int i, npages;
 
 
     if (WARN_ON(!obj->filp))
         return ERR_PTR(-EINVAL);
 
     /* This is the shared memory object that backs the GEM resource */
     mapping = obj->filp->f_mapping;
 
     /* We already BUG_ON() for non-page-aligned sizes in
      * drm_gem_object_init(), so we should never hit this unless
      * driver author is doing something really wrong:
      */
     WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);
 
     npages = obj->size >> PAGE_SHIFT;
 
     pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
     if (pages == NULL)
         return ERR_PTR(-ENOMEM);
 
     mapping_set_unevictable(mapping);
 
     for (i = 0; i < npages; i++) {
         p = shmem_read_mapping_page(mapping, i);
         if (IS_ERR(p))
             goto fail;
         pages[i] = p;
 
         /* Make sure shmem keeps __GFP_DMA32 allocated pages in the
          * correct region during swapin. Note that this requires
          * __GFP_DMA32 to be set in mapping_gfp_mask(inode->i_mapping)
          * so shmem can relocate pages during swapin if required.
          */
         BUG_ON(mapping_gfp_constraint(mapping, __GFP_DMA32) &&
                 (page_to_pfn(p) >= 0x00100000UL));
     }
 
     return pages;
 
 fail:
     mapping_clear_unevictable(mapping);
     pagevec_init(&pvec);
     while (i--) {
         if (!pagevec_add(&pvec, pages[i]))
             drm_gem_check_release_pagevec(&pvec);
     }
     if (pagevec_count(&pvec))
         drm_gem_check_release_pagevec(&pvec);
 
     kvfree(pages);
     return ERR_CAST(p);
 }
 EXPORT_SYMBOL(drm_gem_get_pages);
 
 /**
  * drm_gem_put_pages - helper to free backing pages for a GEM object
  * @obj: obj in question
  * @pages: pages to free
  * @dirty: if true, pages will be marked as dirty
  * @accessed: if true, the pages will be marked as accessed
  */
 void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
         bool dirty, bool accessed)
 {
     int i, npages;
     struct address_space *mapping;
     struct pagevec pvec;
 
     mapping = file_inode(obj->filp)->i_mapping;
     mapping_clear_unevictable(mapping);
 
     /* We already BUG_ON() for non-page-aligned sizes in
      * drm_gem_object_init(), so we should never hit this unless
      * driver author is doing something really wrong:
      */
     WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);
 
     npages = obj->size >> PAGE_SHIFT;
 
     pagevec_init(&pvec);
     for (i = 0; i < npages; i++) {
         if (!pages[i])
             continue;
 
         if (dirty)
             set_page_dirty(pages[i]);
 
         if (accessed)
             mark_page_accessed(pages[i]);
 
         /* Undo the reference we took when populating the table */
         if (!pagevec_add(&pvec, pages[i]))
             drm_gem_check_release_pagevec(&pvec);
     }
     if (pagevec_count(&pvec))
         drm_gem_check_release_pagevec(&pvec);
 
     kvfree(pages);
 }
 EXPORT_SYMBOL(drm_gem_put_pages);
 
 static int objects_lookup(struct drm_file *filp, u32 *handle, int count,
               struct drm_gem_object **objs)
 {
     int i, ret = 0;
     struct drm_gem_object *obj;
 
     spin_lock(&filp->table_lock);
 
     for (i = 0; i < count; i++) {
         /* Check if we currently have a reference on the object */
         obj = idr_find(&filp->object_idr, handle[i]);
         if (!obj) {
             ret = -ENOENT;
             break;
         }
         drm_gem_object_get(obj);
         objs[i] = obj;
     }
     spin_unlock(&filp->table_lock);
 
     return ret;
 }
 
 /**
  * drm_gem_objects_lookup - look up GEM objects from an array of handles
  * @filp: DRM file private date
  * @bo_handles: user pointer to array of userspace handle
  * @count: size of handle array
  * @objs_out: returned pointer to array of drm_gem_object pointers
  *
  * Takes an array of userspace handles and returns a newly allocated array of
  * GEM objects.
  *
  * For a single handle lookup, use drm_gem_object_lookup().
  *
  * Returns:
  *
  * @objs filled in with GEM object pointers. Returned GEM objects need to be
  * released with drm_gem_object_put(). -ENOENT is returned on a lookup
  * failure. 0 is returned on success.
  *
  */
 int drm_gem_objects_lookup(struct drm_file *filp, void __user *bo_handles,
                int count, struct drm_gem_object ***objs_out)
 {
     int ret;
     u32 *handles;
     struct drm_gem_object **objs;
 
     if (!count)
         return 0;
 
     objs = kvmalloc_array(count, sizeof(struct drm_gem_object *),
                  GFP_KERNEL | __GFP_ZERO);
     if (!objs)
         return -ENOMEM;
 
     *objs_out = objs;
 
     handles = kvmalloc_array(count, sizeof(u32), GFP_KERNEL);
     if (!handles) {
         ret = -ENOMEM;
         goto out;
     }
 
     if (copy_from_user(handles, bo_handles, count * sizeof(u32))) {
         ret = -EFAULT;
         DRM_DEBUG("Failed to copy in GEM handles\n");
         goto out;
     }
 
     ret = objects_lookup(filp, handles, count, objs);
 out:
     kvfree(handles);
     return ret;
 
 }
 EXPORT_SYMBOL(drm_gem_objects_lookup);
 
 /**
  * drm_gem_object_lookup - look up a GEM object from its handle
  * @filp: DRM file private date
  * @handle: userspace handle
  *
  * Returns:
  *
  * A reference to the object named by the handle if such exists on @filp, NULL
  * otherwise.
  *
  * If looking up an array of handles, use drm_gem_objects_lookup().
  */
 struct drm_gem_object *
 drm_gem_object_lookup(struct drm_file *filp, u32 handle)
 {
     struct drm_gem_object *obj = NULL;
 
     objects_lookup(filp, &handle, 1, &obj);
     return obj;
 }
 EXPORT_SYMBOL(drm_gem_object_lookup);
 
 /**
  * drm_gem_dma_resv_wait - Wait on GEM object's reservation's objects
  * shared and/or exclusive fences.
  * @filep: DRM file private date
  * @handle: userspace handle
  * @wait_all: if true, wait on all fences, else wait on just exclusive fence
  * @timeout: timeout value in jiffies or zero to return immediately
  *
  * Returns:
  *
  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
  * greater than 0 on success.
  */
 long drm_gem_dma_resv_wait(struct drm_file *filep, u32 handle,
                     bool wait_all, unsigned long timeout)
 {
     long ret;
     struct drm_gem_object *obj;
 
     obj = drm_gem_object_lookup(filep, handle);
     if (!obj) {
         DRM_DEBUG("Failed to look up GEM BO %d\n", handle);
         return -EINVAL;
     }
 
     ret = dma_resv_wait_timeout(obj->resv, dma_resv_usage_rw(wait_all),
                     true, timeout);
     if (ret == 0)
         ret = -ETIME;
     else if (ret > 0)
         ret = 0;
 
     drm_gem_object_put(obj);
 
     return ret;
 }
 EXPORT_SYMBOL(drm_gem_dma_resv_wait);
 
 /**
  * drm_gem_close_ioctl - implementation of the GEM_CLOSE ioctl
  * @dev: drm_device
  * @data: ioctl data
  * @file_priv: drm file-private structure
  *
  * Releases the handle to an mm object.
  */
 int
 drm_gem_close_ioctl(struct drm_device *dev, void *data,
             struct drm_file *file_priv)
 {
     struct drm_gem_close *args = data;
     int ret;
 
     if (!drm_core_check_feature(dev, DRIVER_GEM))
         return -EOPNOTSUPP;
 
     ret = drm_gem_handle_delete(file_priv, args->handle);
 
     return ret;
 }
 
 /**
  * drm_gem_flink_ioctl - implementation of the GEM_FLINK ioctl
  * @dev: drm_device
  * @data: ioctl data
  * @file_priv: drm file-private structure
  *
  * Create a global name for an object, returning the name.
  *
  * Note that the name does not hold a reference; when the object
  * is freed, the name goes away.
  */
 int
 drm_gem_flink_ioctl(struct drm_device *dev, void *data,
             struct drm_file *file_priv)
 {
     struct drm_gem_flink *args = data;
     struct drm_gem_object *obj;
     int ret;
 
     if (!drm_core_check_feature(dev, DRIVER_GEM))
         return -EOPNOTSUPP;
 
     obj = drm_gem_object_lookup(file_priv, args->handle);
     if (obj == NULL)
         return -ENOENT;
 
     mutex_lock(&dev->object_name_lock);
     /* prevent races with concurrent gem_close. */
     if (obj->handle_count == 0) {
         ret = -ENOENT;
         goto err;
     }
 
     if (!obj->name) {
         ret = idr_alloc(&dev->object_name_idr, obj, 1, 0, GFP_KERNEL);
         if (ret < 0)
             goto err;
 
         obj->name = ret;
     }
 
     args->name = (uint64_t) obj->name;
     ret = 0;
 
 err:
     mutex_unlock(&dev->object_name_lock);
     drm_gem_object_put(obj);
     return ret;
 }
 
 /**
  * drm_gem_open_ioctl - implementation of the GEM_OPEN ioctl
  * @dev: drm_device
  * @data: ioctl data
  * @file_priv: drm file-private structure
  *
  * Open an object using the global name, returning a handle and the size.
  *
  * This handle (of course) holds a reference to the object, so the object
  * will not go away until the handle is deleted.
  */
 int
 drm_gem_open_ioctl(struct drm_device *dev, void *data,
            struct drm_file *file_priv)
 {
     struct drm_gem_open *args = data;
     struct drm_gem_object *obj;
     int ret;
     u32 handle;
 
     if (!drm_core_check_feature(dev, DRIVER_GEM))
         return -EOPNOTSUPP;
 
     mutex_lock(&dev->object_name_lock);
     obj = idr_find(&dev->object_name_idr, (int) args->name);
     if (obj) {
         drm_gem_object_get(obj);
     } else {
         mutex_unlock(&dev->object_name_lock);
         return -ENOENT;
     }
 
     /* drm_gem_handle_create_tail unlocks dev->object_name_lock. */
     ret = drm_gem_handle_create_tail(file_priv, obj, &handle);
     if (ret)
         goto err;
 
     args->handle = handle;
     args->size = obj->size;
 
 err:
     drm_gem_object_put(obj);
     return ret;
 }
 
 /**
  * drm_gem_open - initializes GEM file-private structures at devnode open time
  * @dev: drm_device which is being opened by userspace
  * @file_private: drm file-private structure to set up
  *
  * Called at device open time, sets up the structure for handling refcounting
  * of mm objects.
  */
 void
 drm_gem_open(struct drm_device *dev, struct drm_file *file_private)
 {
     idr_init_base(&file_private->object_idr, 1);
     spin_lock_init(&file_private->table_lock);
 }
 
 /**
  * drm_gem_release - release file-private GEM resources
  * @dev: drm_device which is being closed by userspace
  * @file_private: drm file-private structure to clean up
  *
  * Called at close time when the filp is going away.
  *
  * Releases any remaining references on objects by this filp.
  */
 void
 drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
 {
     idr_for_each(&file_private->object_idr,
              &drm_gem_object_release_handle, file_private);
     idr_destroy(&file_private->object_idr);
 }
 
 /**
  * drm_gem_object_release - release GEM buffer object resources
  * @obj: GEM buffer object
  *
  * This releases any structures and resources used by @obj and is the inverse of
  * drm_gem_object_init().
  */
 void
 drm_gem_object_release(struct drm_gem_object *obj)
 {
     WARN_ON(obj->dma_buf);
 
     if (obj->filp)
         fput(obj->filp);
 
     dma_resv_fini(&obj->_resv);
     drm_gem_free_mmap_offset(obj);
 }
 EXPORT_SYMBOL(drm_gem_object_release);
 
 /**
  * drm_gem_object_free - free a GEM object
  * @kref: kref of the object to free
  *
  * Called after the last reference to the object has been lost.
  *
  * Frees the object
  */
 void
 drm_gem_object_free(struct kref *kref)
 {
     struct drm_gem_object *obj =
         container_of(kref, struct drm_gem_object, refcount);
 
     if (WARN_ON(!obj->funcs->free))
         return;
 
     obj->funcs->free(obj);
 }
 EXPORT_SYMBOL(drm_gem_object_free);
 
 /**
  * drm_gem_vm_open - vma->ops->open implementation for GEM
  * @vma: VM area structure
  *
  * This function implements the #vm_operations_struct open() callback for GEM
  * drivers. This must be used together with drm_gem_vm_close().
  */
 void drm_gem_vm_open(struct vm_area_struct *vma)
 {
     struct drm_gem_object *obj = vma->vm_private_data;
 
     drm_gem_object_get(obj);
 }
 EXPORT_SYMBOL(drm_gem_vm_open);
 
 /**
  * drm_gem_vm_close - vma->ops->close implementation for GEM
  * @vma: VM area structure
  *
  * This function implements the #vm_operations_struct close() callback for GEM
  * drivers. This must be used together with drm_gem_vm_open().
  */
 void drm_gem_vm_close(struct vm_area_struct *vma)
 {
     struct drm_gem_object *obj = vma->vm_private_data;
 
     drm_gem_object_put(obj);
 }
 EXPORT_SYMBOL(drm_gem_vm_close);
 
 /**
  * drm_gem_mmap_obj - memory map a GEM object
  * @obj: the GEM object to map
  * @obj_size: the object size to be mapped, in bytes
  * @vma: VMA for the area to be mapped
  *
  * Set up the VMA to prepare mapping of the GEM object using the GEM object's
  * vm_ops. Depending on their requirements, GEM objects can either
  * provide a fault handler in their vm_ops (in which case any accesses to
  * the object will be trapped, to perform migration, GTT binding, surface
  * register allocation, or performance monitoring), or mmap the buffer memory
  * synchronously after calling drm_gem_mmap_obj.
  *
  * This function is mainly intended to implement the DMABUF mmap operation, when
  * the GEM object is not looked up based on its fake offset. To implement the
  * DRM mmap operation, drivers should use the drm_gem_mmap() function.
  *
  * drm_gem_mmap_obj() assumes the user is granted access to the buffer while
  * drm_gem_mmap() prevents unprivileged users from mapping random objects. So
  * callers must verify access restrictions before calling this helper.
  *
  * Return 0 or success or -EINVAL if the object size is smaller than the VMA
  * size, or if no vm_ops are provided.
  */
 int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
              struct vm_area_struct *vma)
 {
     int ret;
 
     /* Check for valid size. */
     if (obj_size < vma->vm_end - vma->vm_start)
         return -EINVAL;
 
     /* Take a ref for this mapping of the object, so that the fault
      * handler can dereference the mmap offset's pointer to the object.
      * This reference is cleaned up by the corresponding vm_close
      * (which should happen whether the vma was created by this call, or
      * by a vm_open due to mremap or partial unmap or whatever).
      */
     drm_gem_object_get(obj);
 
     vma->vm_private_data = obj;
     vma->vm_ops = obj->funcs->vm_ops;
 
     if (obj->funcs->mmap) {
         ret = obj->funcs->mmap(obj, vma);
         if (ret)
             goto err_drm_gem_object_put;
         WARN_ON(!(vma->vm_flags & VM_DONTEXPAND));
     } else {
         if (!vma->vm_ops) {
             ret = -EINVAL;
             goto err_drm_gem_object_put;
         }
 
         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
         vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
         vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
     }
 
     return 0;
 
 err_drm_gem_object_put:
     drm_gem_object_put(obj);
     return ret;
 }
 EXPORT_SYMBOL(drm_gem_mmap_obj);
 
 /**
  * drm_gem_mmap - memory map routine for GEM objects
  * @filp: DRM file pointer
  * @vma: VMA for the area to be mapped
  *
  * If a driver supports GEM object mapping, mmap calls on the DRM file
  * descriptor will end up here.
  *
  * Look up the GEM object based on the offset passed in (vma->vm_pgoff will
  * contain the fake offset we created when the GTT map ioctl was called on
  * the object) and map it with a call to drm_gem_mmap_obj().
  *
  * If the caller is not granted access to the buffer object, the mmap will fail
  * with EACCES. Please see the vma manager for more information.
  */
 int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 {
     struct drm_file *priv = filp->private_data;
     struct drm_device *dev = priv->minor->dev;
     struct drm_gem_object *obj = NULL;
     struct drm_vma_offset_node *node;
     int ret;
 
     if (drm_dev_is_unplugged(dev))
         return -ENODEV;
 
     drm_vma_offset_lock_lookup(dev->vma_offset_manager);
     node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
                           vma->vm_pgoff,
                           vma_pages(vma));
     if (likely(node)) {
         obj = container_of(node, struct drm_gem_object, vma_node);
         /*
          * When the object is being freed, after it hits 0-refcnt it
          * proceeds to tear down the object. In the process it will
          * attempt to remove the VMA offset and so acquire this
          * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
          * that matches our range, we know it is in the process of being
          * destroyed and will be freed as soon as we release the lock -
          * so we have to check for the 0-refcnted object and treat it as
          * invalid.
          */
         if (!kref_get_unless_zero(&obj->refcount))
             obj = NULL;
     }
     drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
 
     if (!obj)
         return -EINVAL;
 
     if (!drm_vma_node_is_allowed(node, priv)) {
         drm_gem_object_put(obj);
         return -EACCES;
     }
 
     ret = drm_gem_mmap_obj(obj, drm_vma_node_size(node) << PAGE_SHIFT,
                    vma);
 
     drm_gem_object_put(obj);
 
     return ret;
 }
 EXPORT_SYMBOL(drm_gem_mmap);
 
 void drm_gem_print_info(struct drm_printer *p, unsigned int indent,
             const struct drm_gem_object *obj)
 {
     drm_printf_indent(p, indent, "name=%d\n", obj->name);
     drm_printf_indent(p, indent, "refcount=%u\n",
               kref_read(&obj->refcount));
     drm_printf_indent(p, indent, "start=%08lx\n",
               drm_vma_node_start(&obj->vma_node));
     drm_printf_indent(p, indent, "size=%zu\n", obj->size);
     drm_printf_indent(p, indent, "imported=%s\n",
               str_yes_no(obj->import_attach));
 
     if (obj->funcs->print_info)
         obj->funcs->print_info(p, indent, obj);
 }
 
 int drm_gem_pin(struct drm_gem_object *obj)
 {
     if (obj->funcs->pin)
         return obj->funcs->pin(obj);
     else
         return 0;
 }
 
 void drm_gem_unpin(struct drm_gem_object *obj)
 {
     if (obj->funcs->unpin)
         obj->funcs->unpin(obj);
 }
 
 int drm_gem_vmap(struct drm_gem_object *obj, struct iosys_map *map)
 {
     int ret;
 
     if (!obj->funcs->vmap)
         return -EOPNOTSUPP;
 
     ret = obj->funcs->vmap(obj, map);
     if (ret)
         return ret;
     else if (iosys_map_is_null(map))
         return -ENOMEM;
 
     return 0;
 }
 EXPORT_SYMBOL(drm_gem_vmap);
 
 void drm_gem_vunmap(struct drm_gem_object *obj, struct iosys_map *map)
 {
     if (iosys_map_is_null(map))
         return;
 
     if (obj->funcs->vunmap)
         obj->funcs->vunmap(obj, map);
 
     /* Always set the mapping to NULL. Callers may rely on this. */
     iosys_map_clear(map);
 }
 EXPORT_SYMBOL(drm_gem_vunmap);
 
 /**
  * drm_gem_lock_reservations - Sets up the ww context and acquires
  * the lock on an array of GEM objects.
  *
  * Once you've locked your reservations, you'll want to set up space
  * for your shared fences (if applicable), submit your job, then
  * drm_gem_unlock_reservations().
  *
  * @objs: drm_gem_objects to lock
  * @count: Number of objects in @objs
  * @acquire_ctx: struct ww_acquire_ctx that will be initialized as
  * part of tracking this set of locked reservations.
  */
 int
 drm_gem_lock_reservations(struct drm_gem_object **objs, int count,
               struct ww_acquire_ctx *acquire_ctx)
 {
     int contended = -1;
     int i, ret;
 
     ww_acquire_init(acquire_ctx, &reservation_ww_class);
 
 retry:
     if (contended != -1) {
         struct drm_gem_object *obj = objs[contended];
 
         ret = dma_resv_lock_slow_interruptible(obj->resv,
                                  acquire_ctx);
         if (ret) {
             ww_acquire_fini(acquire_ctx);
             return ret;
         }
     }
 
     for (i = 0; i < count; i++) {
         if (i == contended)
             continue;
 
         ret = dma_resv_lock_interruptible(objs[i]->resv,
                                 acquire_ctx);
         if (ret) {
             int j;
 
             for (j = 0; j < i; j++)
                 dma_resv_unlock(objs[j]->resv);
 
             if (contended != -1 && contended >= i)
                 dma_resv_unlock(objs[contended]->resv);
 
             if (ret == -EDEADLK) {
                 contended = i;
                 goto retry;
             }
 
             ww_acquire_fini(acquire_ctx);
             return ret;
         }
     }
 
     ww_acquire_done(acquire_ctx);
 
     return 0;
 }
 EXPORT_SYMBOL(drm_gem_lock_reservations);
 
 void
 drm_gem_unlock_reservations(struct drm_gem_object **objs, int count,
                 struct ww_acquire_ctx *acquire_ctx)
 {
     int i;
 
     for (i = 0; i < count; i++)
         dma_resv_unlock(objs[i]->resv);
 
     ww_acquire_fini(acquire_ctx);
 }
 EXPORT_SYMBOL(drm_gem_unlock_reservations);

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