[Linaro-mm-sig] Re: [PATCH 1/2] dma-buf: heaps: DMA_HEAP_IOCTL_ALLOC_READ_FILE framework

Am 11.07.24 um 09:42 schrieb Huan Yang:

Some user may need load file into dma-buf, current way is:

1. allocate a dma-buf, get dma-buf fd
2. mmap dma-buf fd into vaddr
3. read(file_fd, vaddr, fsz)

This is too heavy if fsz reached to GB.

You need to describe a bit more why that is to heavy. I can only assume you need to save memory bandwidth and avoid the extra copy with the CPU.

This patch implement a feature called DMA_HEAP_IOCTL_ALLOC_READ_FILE. User need to offer a file_fd which you want to load into dma-buf, then, it promise if you got a dma-buf fd, it will contains the file content.

Interesting idea, that has at least more potential than trying to enable direct I/O on mmap()ed DMA-bufs.

The approach with the new IOCTL might not work because it is a very specialized use case.

But IIRC there was a copy_file_range callback in the file_operations structure you could use for that. I'm just not sure when and how that's used with the copy_file_range() system call.

Regards, Christian.

Notice, file_fd depends on user how to open this file. So, both buffer I/O and Direct I/O is supported.

Signed-off-by: Huan Yang link@vivo.com

drivers/dma-buf/dma-heap.c | 525 +++++++++++++++++++++++++++++++++- include/linux/dma-heap.h | 57 +++- include/uapi/linux/dma-heap.h | 32 +++ 3 files changed, 611 insertions(+), 3 deletions(-)

diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index 2298ca5e112e..abe17281adb8 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -15,9 +15,11 @@ #include <linux/list.h> #include <linux/slab.h> #include <linux/nospec.h> +#include <linux/highmem.h> #include <linux/uaccess.h> #include <linux/syscalls.h> #include <linux/dma-heap.h> +#include <linux/vmalloc.h> #include <uapi/linux/dma-heap.h> #define DEVNAME "dma_heap" @@ -43,12 +45,462 @@ struct dma_heap { struct cdev heap_cdev; }; +/**

• • struct dma_heap_file - wrap the file, read task for dma_heap allocate use.
• • @file: file to read from.
• • @cred: kthread use, user cred copy to use for the read.
• • @max_batch: maximum batch size to read, if collect match batch,

• • 	trigger read, default 128MB, must below file size.
    

• • @fsz: file size.
• • @direct: use direct IO?
• */

+struct dma_heap_file {

• struct file *file;
• struct cred *cred;
• size_t max_batch;
• size_t fsz;
• bool direct;

+};

+/**

• • struct dma_heap_file_work - represents a dma_heap file read real work.
• • @vaddr: contigous virtual address alloc by vmap, file read need.
• • @start_size: file read start offset, same to @dma_heap_file_task->roffset.
• • @need_size: file read need size, same to @dma_heap_file_task->rsize.
• • @heap_file: file wrapper.
• • @list: child node of @dma_heap_file_control->works.
• • @refp: same @dma_heap_file_task->ref, if end of read, put ref.
• • @failp: if any work io failed, set it true, pointp @dma_heap_file_task->fail.
• */

+struct dma_heap_file_work {

• void *vaddr;
• ssize_t start_size;
• ssize_t need_size;
• struct dma_heap_file *heap_file;
• struct list_head list;
• atomic_t *refp;
• bool *failp;

+};

+/**

• • struct dma_heap_file_task - represents a dma_heap file read process
• • @ref: current file work counter, if zero, allocate and read

• • 	done.
    

• • @roffset: last read offset, current prepared work' begin file

• • 	start offset.
    

• • @rsize: current allocated page size use to read, if reach rbatch,

• • 	trigger commit.
    

• • @rbatch: current prepared work's batch, below @dma_heap_file's

• • 	batch.
    

• • @heap_file: current dma_heap_file
• • @parray: used for vmap, size is @dma_heap_file's batch's number

• • 	pages.(this is maximum). Due to single thread file read,
    

• • 	one page array reuse each work prepare is OK.
    

• • 	Each index in parray is PAGE_SIZE.(vmap need)
    

• • @pindex: current allocated page filled in @parray's index.
• • @fail: any work failed when file read?
• • dma_heap_file_task is the production of file read, will prepare each work
• • during allocate dma_buf pages, if match current batch, then trigger commit
• • and prepare next work. After all batch queued, user going on prepare dma_buf
• • and so on, but before return dma_buf fd, need to wait file read end and
• • check read result.
• */

+struct dma_heap_file_task {

• atomic_t ref;
• size_t roffset;
• size_t rsize;
• size_t rbatch;
• struct dma_heap_file *heap_file;
• struct page **parray;
• unsigned int pindex;
• bool fail;

+};

+/**

• • struct dma_heap_file_control - global control of dma_heap file read.
• • @works: @dma_heap_file_work's list head.
• • @lock: only lock for @works.
• • @threadwq: wait queue for @work_thread, if commit work, @work_thread

• • 	wakeup and read this work's file contains.
    

• • @workwq: used for main thread wait for file read end, if allocation

• • 	end before file read. @dma_heap_file_task ref effect this.
    

• • @work_thread: file read kthread. the dma_heap_file_task work's consumer.
• • @heap_fwork_cachep: @dma_heap_file_work's cachep, it's alloc/free frequently.
• • @nr_work: global number of how many work committed.
• */

+struct dma_heap_file_control {

• struct list_head works;
• spinlock_t lock;
• wait_queue_head_t threadwq;
• wait_queue_head_t workwq;
• struct task_struct *work_thread;
• struct kmem_cache *heap_fwork_cachep;
• atomic_t nr_work;

+};

+static struct dma_heap_file_control *heap_fctl; static LIST_HEAD(heap_list); static DEFINE_MUTEX(heap_list_lock); static dev_t dma_heap_devt; static struct class *dma_heap_class; static DEFINE_XARRAY_ALLOC(dma_heap_minors); +/**

• • map_pages_to_vaddr - map each scatter page into contiguous virtual address.
• • @heap_ftask: prepared and need to commit's work.
• • Cached pages need to trigger file read, this function map each scatter page
• • into contiguous virtual address, so that file read can easy use.
• • Now that we get vaddr page, cached pages can return to original user, so we
• • will not effect dma-buf export even if file read not end.
• */

+static void *map_pages_to_vaddr(struct dma_heap_file_task *heap_ftask) +{

• return vmap(heap_ftask->parray, heap_ftask->pindex, VM_MAP,

•     PAGE_KERNEL);
  

+}

+bool dma_heap_prepare_file_read(struct dma_heap_file_task *heap_ftask,

• 		struct page *page)
  

+{

• struct page **array = heap_ftask->parray;
• int index = heap_ftask->pindex;
• int num = compound_nr(page), i;
• unsigned long sz = page_size(page);
• heap_ftask->rsize += sz;
• for (i = 0; i < num; ++i)

• array[index++] = &page[i];
  

• heap_ftask->pindex = index;
• return heap_ftask->rsize >= heap_ftask->rbatch;

+}

+static struct dma_heap_file_work * +init_file_work(struct dma_heap_file_task *heap_ftask) +{

• struct dma_heap_file_work *heap_fwork;
• struct dma_heap_file *heap_file = heap_ftask->heap_file;
• if (READ_ONCE(heap_ftask->fail))

• return NULL;
  

• heap_fwork = kmem_cache_alloc(heap_fctl->heap_fwork_cachep, GFP_KERNEL);
• if (unlikely(!heap_fwork))

• return NULL;
  

• heap_fwork->vaddr = map_pages_to_vaddr(heap_ftask);
• if (unlikely(!heap_fwork->vaddr)) {

• kmem_cache_free(heap_fctl->heap_fwork_cachep, heap_fwork);
  

• return NULL;
  

• }
• heap_fwork->heap_file = heap_file;
• heap_fwork->start_size = heap_ftask->roffset;
• heap_fwork->need_size = heap_ftask->rsize;
• heap_fwork->refp = &heap_ftask->ref;
• heap_fwork->failp = &heap_ftask->fail;
• atomic_inc(&heap_ftask->ref);
• return heap_fwork;

+}

+static void destroy_file_work(struct dma_heap_file_work *heap_fwork) +{

• vunmap(heap_fwork->vaddr);
• atomic_dec(heap_fwork->refp);
• wake_up(&heap_fctl->workwq);
• kmem_cache_free(heap_fctl->heap_fwork_cachep, heap_fwork);

+}

+int dma_heap_submit_file_read(struct dma_heap_file_task *heap_ftask) +{

• struct dma_heap_file_work *heap_fwork = init_file_work(heap_ftask);
• struct page *last = NULL;
• struct dma_heap_file *heap_file = heap_ftask->heap_file;
• size_t start = heap_ftask->roffset;
• struct file *file = heap_file->file;
• size_t fsz = heap_file->fsz;
• if (unlikely(!heap_fwork))

• return -ENOMEM;
  

• /**

• * If file size is not page aligned, direct io can't process the tail.
  

• * So, if reach to tail, remain the last page use buffer read.
  

• */
  

• if (heap_file->direct && start + heap_ftask->rsize > fsz) {

• heap_fwork->need_size -= PAGE_SIZE;
  

• last = heap_ftask->parray[heap_ftask->pindex - 1];
  

• }
• spin_lock(&heap_fctl->lock);
• list_add_tail(&heap_fwork->list, &heap_fctl->works);
• spin_unlock(&heap_fctl->lock);
• atomic_inc(&heap_fctl->nr_work);
• wake_up(&heap_fctl->threadwq);
• if (last) {

• char *buf, *pathp;
  

• ssize_t err;
  

• void *buffer;
  

• buf = kmalloc(PATH_MAX, GFP_KERNEL);
  

• if (unlikely(!buf))
  

• 	return -ENOMEM;
  

• start = PAGE_ALIGN_DOWN(fsz);
  

• pathp = file_path(file, buf, PATH_MAX);
  

• if (IS_ERR(pathp)) {
  

• 	kfree(buf);
  

• 	return PTR_ERR(pathp);
  

• }
  

• buffer = kmap_local_page(last); // use page's kaddr.
  

• err = kernel_read_file_from_path(pathp, start, &buffer,
  

• 				 fsz - start, &fsz,
  

• 				 READING_POLICY);
  

• kunmap_local(buffer);
  

• kfree(buf);
  

• if (err < 0) {
  

• 	pr_err("failed to use buffer kernel_read_file %s, err=%ld, [%ld, %ld], f_sz=%ld\n",
  

• 	       pathp, err, start, fsz, fsz);
  

• 	return err;
  

• }
  

• }
• heap_ftask->roffset += heap_ftask->rsize;
• heap_ftask->rsize = 0;
• heap_ftask->pindex = 0;
• heap_ftask->rbatch = min_t(size_t,

• 		   PAGE_ALIGN(fsz) - heap_ftask->roffset,
  

• 		   heap_ftask->rbatch);
  

• return 0;

+}

+bool dma_heap_wait_for_file_read(struct dma_heap_file_task *heap_ftask) +{

• wait_event_freezable(heap_fctl->workwq,

• 	     atomic_read(&heap_ftask->ref) == 0);
  

• return heap_ftask->fail;

+}

+bool dma_heap_destroy_file_read(struct dma_heap_file_task *heap_ftask) +{

• bool fail;
• dma_heap_wait_for_file_read(heap_ftask);
• fail = heap_ftask->fail;
• kvfree(heap_ftask->parray);
• kfree(heap_ftask);
• return fail;

+}

+struct dma_heap_file_task * +dma_heap_declare_file_read(struct dma_heap_file *heap_file) +{

• struct dma_heap_file_task *heap_ftask =

• kzalloc(sizeof(*heap_ftask), GFP_KERNEL);
  

• if (unlikely(!heap_ftask))

• return NULL;
  

• /**

• * Batch is the maximum size which we prepare work will meet.
  

• * So, direct alloc this number's page array is OK.
  

• */
  

• heap_ftask->parray = kvmalloc_array(heap_file->max_batch >> PAGE_SHIFT,

• 			    sizeof(struct page *), GFP_KERNEL);
  

• if (unlikely(!heap_ftask->parray))

• goto put;
  

• heap_ftask->heap_file = heap_file;
• heap_ftask->rbatch = heap_file->max_batch;
• return heap_ftask;

+put:

• kfree(heap_ftask);
• return NULL;

+}

+static void __work_this_io(struct dma_heap_file_work *heap_fwork) +{

• struct dma_heap_file *heap_file = heap_fwork->heap_file;
• struct file *file = heap_file->file;
• ssize_t start = heap_fwork->start_size;
• ssize_t size = heap_fwork->need_size;
• void *buffer = heap_fwork->vaddr;
• const struct cred *old_cred;
• ssize_t err;
• // use real task's cred to read this file.
• old_cred = override_creds(heap_file->cred);
• err = kernel_read_file(file, start, &buffer, size, &heap_file->fsz,

• 	       READING_POLICY);
  

• if (err < 0) {

• pr_err("use kernel_read_file, err=%ld, [%ld, %ld], f_sz=%ld\n",
  

•        err, start, (start + size), heap_file->fsz);
  

• WRITE_ONCE(*heap_fwork->failp, true);
  

• }
• // recovery to my cred.
• revert_creds(old_cred);

+}

+static int dma_heap_file_control_thread(void *data) +{

• struct dma_heap_file_control *heap_fctl =

• (struct dma_heap_file_control *)data;
  

• struct dma_heap_file_work *worker, *tmp;
• int nr_work;
• LIST_HEAD(pages);
• LIST_HEAD(workers);
• while (true) {

• wait_event_freezable(heap_fctl->threadwq,
  

• 		     atomic_read(&heap_fctl->nr_work) > 0);
  

+recheck:

• spin_lock(&heap_fctl->lock);
  

• list_splice_init(&heap_fctl->works, &workers);
  

• spin_unlock(&heap_fctl->lock);
  

• if (unlikely(kthread_should_stop())) {
  

• 	list_for_each_entry_safe(worker, tmp, &workers, list) {
  

• 		list_del(&worker->list);
  

• 		destroy_file_work(worker);
  

• 	}
  

• 	break;
  

• }
  

• nr_work = 0;
  

• list_for_each_entry_safe(worker, tmp, &workers, list) {
  

• 	++nr_work;
  

• 	list_del(&worker->list);
  

• 	__work_this_io(worker);
  

• 	destroy_file_work(worker);
  

• }
  

• atomic_sub(nr_work, &heap_fctl->nr_work);
  

• if (atomic_read(&heap_fctl->nr_work) > 0)
  

• 	goto recheck;
  

• }
• return 0;

+}

+size_t dma_heap_file_size(struct dma_heap_file *heap_file) +{

• return heap_file->fsz;

+}

+static int prepare_dma_heap_file(struct dma_heap_file *heap_file, int file_fd,

• 		 size_t batch)
  

+{

• struct file *file;
• size_t fsz;
• int ret;
• file = fget(file_fd);
• if (!file)

• return -EINVAL;
  

• fsz = i_size_read(file_inode(file));
• if (fsz < batch) {

• ret = -EINVAL;
  

• goto err;
  

• }
• /**

• * Selinux block our read, but actually we are reading the stand-in
  

• * for this file.
  

• * So save current's cred and when going to read, override mine, and
  

• * end of read, revert.
  

• */
  

• heap_file->cred = prepare_kernel_cred(current);
• if (unlikely(!heap_file->cred)) {

• ret = -ENOMEM;
  

• goto err;
  

• }
• heap_file->file = file;
• heap_file->max_batch = batch;
• heap_file->fsz = fsz;
• heap_file->direct = file->f_flags & O_DIRECT;

+#define DMA_HEAP_SUGGEST_DIRECT_IO_SIZE (1UL << 30)

• if (!heap_file->direct && fsz >= DMA_HEAP_SUGGEST_DIRECT_IO_SIZE)

• pr_warn("alloc read file better to use O_DIRECT to read larget file\n");
  

• return 0;

+err:

• fput(file);
• return ret;

+}

+static void destroy_dma_heap_file(struct dma_heap_file *heap_file) +{

• fput(heap_file->file);
• put_cred(heap_file->cred);

+}

+static int dma_heap_buffer_alloc_read_file(struct dma_heap *heap, int file_fd,

• 			   size_t batch, unsigned int fd_flags,
  

• 			   unsigned int heap_flags)
  

+{

• struct dma_buf *dmabuf;
• int fd;
• struct dma_heap_file heap_file;
• fd = prepare_dma_heap_file(&heap_file, file_fd, batch);
• if (fd)

• goto error_file;
  

• dmabuf = heap->ops->allocate_read_file(heap, &heap_file, fd_flags,

• 			       heap_flags);
  

• if (IS_ERR(dmabuf)) {

• fd = PTR_ERR(dmabuf);
  

• goto error;
  

• }
• fd = dma_buf_fd(dmabuf, fd_flags);
• if (fd < 0) {

• dma_buf_put(dmabuf);
  

• /* just return, as put will call release and that will free */
  

• }

+error:

• destroy_dma_heap_file(&heap_file);

+error_file:

• return fd;

+}

• static int dma_heap_buffer_alloc(struct dma_heap *heap, size_t len, u32 fd_flags, u64 heap_flags)

@@ -93,6 +545,38 @@ static int dma_heap_open(struct inode *inode, struct file *file) return 0; } +static long dma_heap_ioctl_allocate_read_file(struct file *file, void *data) +{

• struct dma_heap_allocation_file_data *heap_allocation_file = data;
• struct dma_heap *heap = file->private_data;
• int fd;
• if (heap_allocation_file->fd || !heap_allocation_file->file_fd)

• return -EINVAL;
  

• if (heap_allocation_file->fd_flags & ~DMA_HEAP_VALID_FD_FLAGS)

• return -EINVAL;
  

• if (heap_allocation_file->heap_flags & ~DMA_HEAP_VALID_HEAP_FLAGS)

• return -EINVAL;
  

• if (!heap->ops->allocate_read_file)

• return -EINVAL;
  

• fd = dma_heap_buffer_alloc_read_file(

• heap, heap_allocation_file->file_fd,
  

• heap_allocation_file->batch ?
  

• 	PAGE_ALIGN(heap_allocation_file->batch) :
  

• 	DEFAULT_ADI_BATCH,
  

• heap_allocation_file->fd_flags,
  

• heap_allocation_file->heap_flags);
  

• if (fd < 0)

• return fd;
  

• heap_allocation_file->fd = fd;
• return 0;

+}

• static long dma_heap_ioctl_allocate(struct file *file, void *data) { struct dma_heap_allocation_data *heap_allocation = data;

@@ -121,6 +605,7 @@ static long dma_heap_ioctl_allocate(struct file *file, void *data) static unsigned int dma_heap_ioctl_cmds[] = { DMA_HEAP_IOCTL_ALLOC,

• DMA_HEAP_IOCTL_ALLOC_AND_READ, };

static long dma_heap_ioctl(struct file *file, unsigned int ucmd, @@ -170,6 +655,9 @@ static long dma_heap_ioctl(struct file *file, unsigned int ucmd, case DMA_HEAP_IOCTL_ALLOC: ret = dma_heap_ioctl_allocate(file, kdata); break;

• case DMA_HEAP_IOCTL_ALLOC_AND_READ:

• ret = dma_heap_ioctl_allocate_read_file(file, kdata);
  

• break;
  

  default: ret = -ENOTTY; goto err;

@@ -316,11 +804,44 @@ static int dma_heap_init(void) dma_heap_class = class_create(DEVNAME); if (IS_ERR(dma_heap_class)) {

• unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
  

• return PTR_ERR(dma_heap_class);
  

• ret = PTR_ERR(dma_heap_class);
  

• goto fail_class;
  

  } dma_heap_class->devnode = dma_heap_devnode;

• heap_fctl = kzalloc(sizeof(*heap_fctl), GFP_KERNEL);
• if (unlikely(!heap_fctl)) {

• ret =  -ENOMEM;
  

• goto fail_alloc;
  

• }
• INIT_LIST_HEAD(&heap_fctl->works);
• init_waitqueue_head(&heap_fctl->threadwq);
• init_waitqueue_head(&heap_fctl->workwq);
• heap_fctl->work_thread = kthread_run(dma_heap_file_control_thread,

• 			     heap_fctl, "heap_fwork_t");
  

• if (IS_ERR(heap_fctl->work_thread)) {

• ret = -ENOMEM;
  

• goto fail_thread;
  

• }
• heap_fctl->heap_fwork_cachep = KMEM_CACHE(dma_heap_file_work, 0);
• if (unlikely(!heap_fctl->heap_fwork_cachep)) {

• ret = -ENOMEM;
  

• goto fail_cache;
  

• }
• return 0;

+fail_cache:

• kthread_stop(heap_fctl->work_thread);

+fail_thread:

• kfree(heap_fctl);

+fail_alloc:

• class_destroy(dma_heap_class);

+fail_class:

• unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
• return ret; } subsys_initcall(dma_heap_init);

diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h index 064bad725061..9c25383f816c 100644 --- a/include/linux/dma-heap.h +++ b/include/linux/dma-heap.h @@ -12,12 +12,17 @@ #include <linux/cdev.h> #include <linux/types.h> +#define DEFAULT_ADI_BATCH (128 << 20)

• struct dma_heap;

+struct dma_heap_file_task; +struct dma_heap_file; /**

• struct dma_heap_ops - ops to operate on a given heap
• @allocate: allocate dmabuf and return struct dma_buf ptr

• • @allocate_read_file: allocate dmabuf and read file, then return struct
• • dma_buf ptr.
  • allocate returns dmabuf on success, ERR_PTR(-errno) on error.
  */ struct dma_heap_ops {

@@ -25,6 +30,11 @@ struct dma_heap_ops { unsigned long len, u32 fd_flags, u64 heap_flags);

• struct dma_buf *(*allocate_read_file)(struct dma_heap *heap,

• 			      struct dma_heap_file *heap_file,
  

• 			      u32 fd_flags,
  

• 			      u64 heap_flags);
  

  };

/** @@ -65,4 +75,49 @@ const char *dma_heap_get_name(struct dma_heap *heap); */ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info); +/**

• • dma_heap_destroy_file_read - waits for a file read to complete then destroy it
• • Returns: true if the file read failed, false otherwise
• */

+bool dma_heap_destroy_file_read(struct dma_heap_file_task *heap_ftask);

+/**

• • dma_heap_wait_for_file_read - waits for a file read to complete
• • Returns: true if the file read failed, false otherwise
• */

+bool dma_heap_wait_for_file_read(struct dma_heap_file_task *heap_ftask);

+/**

• • dma_heap_alloc_file_read - Declare a task to read file when allocate pages.
• • @heap_file: target file to read
• • Return NULL if failed, otherwise return a struct pointer.
• */

+struct dma_heap_file_task * +dma_heap_declare_file_read(struct dma_heap_file *heap_file);

+/**

• • dma_heap_prepare_file_read - cache each allocated page until we meet this batch.
• • @heap_ftask: prepared and need to commit's work.
• • @page: current allocated page. don't care which order.
• • Returns true if reach to batch, false so go on prepare.
• */

+bool dma_heap_prepare_file_read(struct dma_heap_file_task *heap_ftask,

• 		struct page *page);
  

+/**

• • dma_heap_commit_file_read - prepare collect enough memory, going to trigger IO
• • @heap_ftask: info that current IO needs
• • This commit will also check if reach to tail read.
• • For direct I/O submissions, it is necessary to pay attention to file reads
• • that are not page-aligned. For the unaligned portion of the read, buffer IO
• • needs to be triggered.
• • Returns:
• • 0 if all right, -errno if something wrong
• */

+int dma_heap_submit_file_read(struct dma_heap_file_task *heap_ftask); +size_t dma_heap_file_size(struct dma_heap_file *heap_file);

• #endif /* _DMA_HEAPS_H */

diff --git a/include/uapi/linux/dma-heap.h b/include/uapi/linux/dma-heap.h index a4cf716a49fa..8c20e8b74eed 100644 --- a/include/uapi/linux/dma-heap.h +++ b/include/uapi/linux/dma-heap.h @@ -39,6 +39,27 @@ struct dma_heap_allocation_data { __u64 heap_flags; }; +/**

• • struct dma_heap_allocation_file_data - metadata passed from userspace for

• •                                  allocations and read file
    

• • @fd: will be populated with a fd which provides the

• • 	handle to the allocated dma-buf
    

• • @file_fd: file descriptor to read from(suggested to use O_DIRECT open file)
• • @batch: how many memory alloced then file read(bytes), default 128MB

• • 	will auto aligned to PAGE_SIZE
    

• • @fd_flags: file descriptor flags used when allocating
• • @heap_flags: flags passed to heap
• • Provided by userspace as an argument to the ioctl
• */

+struct dma_heap_allocation_file_data {

• __u32 fd;
• __u32 file_fd;
• __u32 batch;
• __u32 fd_flags;
• __u64 heap_flags;

+};

• #define DMA_HEAP_IOC_MAGIC 'H'

/** @@ -50,4 +71,15 @@ struct dma_heap_allocation_data { #define DMA_HEAP_IOCTL_ALLOC _IOWR(DMA_HEAP_IOC_MAGIC, 0x0,\ struct dma_heap_allocation_data) +/**

• • DOC: DMA_HEAP_IOCTL_ALLOC_AND_READ - allocate memory from pool and both

• • 			read file when allocate memory.
    

• • Takes a dma_heap_allocation_file_data struct and returns it with the fd field
• • populated with the dmabuf handle of the allocation. When return, the dma-buf
• • content is read from file.
• */

+#define DMA_HEAP_IOCTL_ALLOC_AND_READ \

• _IOWR(DMA_HEAP_IOC_MAGIC, 0x1, struct dma_heap_allocation_file_data)
• #endif /* _UAPI_LINUX_DMABUF_POOL_H */