Message-ID: <99364176-a7f0-4a17-8889-75ff92d5694e@amd.com>
Date: Mon, 15 Jul 2024 14:32:57 +0200
From: Christian König <christian.koenig@....com>
To: Huan Yang <link@...o.com>, Sumit Semwal <sumit.semwal@...aro.org>,
 Benjamin Gaignard <benjamin.gaignard@...labora.com>,
 Brian Starkey <Brian.Starkey@....com>, John Stultz <jstultz@...gle.com>,
 "T.J. Mercier" <tjmercier@...gle.com>, linux-media@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org,
 linux-kernel@...r.kernel.org, opensource.kernel@...o.com
Subject: Re: [PATCH 1/2] dma-buf: heaps: DMA_HEAP_IOCTL_ALLOC_READ_FILE
 framework

Am 15.07.24 um 11:11 schrieb Daniel Vetter:
> On Thu, Jul 11, 2024 at 11:00:02AM +0200, Christian König wrote:
>> 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.
> I'm not sure any of those help, because internally they're all still based
> on struct page (or maybe in the future on folios). And that's the thing
> dma-buf can't give you, at least without peaking behind the curtain.
>
> I think an entirely different option would be malloc+udmabuf. That
> essentially handles the impendence-mismatch between direct I/O and dma-buf
> on the dma-buf side. The downside is that it'll make the permanently
> pinned memory accounting and tracking issues even more apparent, but I
> guess eventually we do need to sort that one out.

Oh, very good idea!

Just one minor correction: it's not malloc+udmabuf, but rather 
create_memfd()+udmabuf.

And you need to complete your direct I/O before creating the udmabuf 
since that reference will prevent direct I/O from working.

Regards,
Christian.



>
> And since all the patches here are only for the pages system heap I'm
> guess udmabuf should work out for the use-case here? Worth a shot at
> least.
> -Sima
>
>> 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@...o.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 */

Powered by blists - more mailing lists