Message-ID: <a9aa7cba-e88e-5881-fbdd-2407fe11d1ff@redhat.com>
Date:	Wed, 8 Jun 2016 10:35:53 -0700
From:	Laura Abbott <labbott@...hat.com>
To:	Liviu Dudau <Liviu.Dudau@....com>
Cc:	Sumit Semwal <sumit.semwal@...aro.org>,
	John Stultz <john.stultz@...aro.org>,
	Arve Hjønnevåg <arve@...roid.com>,
	Riley Andrews <riandrews@...roid.com>,
	Laura Abbott <labbott@...oraproject.org>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	linaro-mm-sig@...ts.linaro.org, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org,
	Eun Taik Lee <eun.taik.lee@...sung.com>,
	Jon Medhurst <tixy@...aro.org>,
	Mitchel Humpherys <mitchelh@...eaurora.org>,
	Jeremy Gebben <jgebben@...eaurora.org>,
	Bryan Huntsman <bryanh@...eaurora.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Android Kernel Team <kernel-team@...roid.com>
Subject: Re: [RFC][PATCH 6/6] staging: android: ion: Introduce new ioctls for
 dynamic heaps

On 06/08/2016 06:50 AM, Liviu Dudau wrote:
> On Mon, Jun 06, 2016 at 11:23:33AM -0700, Laura Abbott wrote:
>> From: Laura Abbott <labbott@...oraproject.org>
>>
>>
>> The Ion ABI for heaps is limiting to work with for more complex systems.
>> Heaps have to be registered at boot time with known ids available to
>> userspace. This becomes a tight ABI which is prone to breakage.
>>
>> Introduce a new mechanism for registering heap ids dynamically. A base
>> set of heap ids are registered at boot time but there is no knowledge
>> of fallbacks. Fallback information can be remapped and changed
>> dynamically. Information about available heaps can also be queried with
>> an ioctl to avoid the need to have heap ids be an ABI with userspace.
>>
>> Signed-off-by: Laura Abbott <labbott@...hat.com>
>> ---
>>  drivers/staging/android/ion/ion-ioctl.c | 109 +++++++++++++++++--
>>  drivers/staging/android/ion/ion.c       | 184 ++++++++++++++++++++++++++++++--
>>  drivers/staging/android/ion/ion_priv.h  |  15 +++
>>  drivers/staging/android/uapi/ion.h      | 135 +++++++++++++++++++++++
>>  4 files changed, 426 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/staging/android/ion/ion-ioctl.c b/drivers/staging/android/ion/ion-ioctl.c
>> index 45b89e8..169cad8 100644
>> --- a/drivers/staging/android/ion/ion-ioctl.c
>> +++ b/drivers/staging/android/ion/ion-ioctl.c
>> @@ -22,6 +22,49 @@
>>  #include "ion_priv.h"
>>  #include "compat_ion.h"
>>
>> +union ion_ioctl_arg {
>> +	struct ion_fd_data fd;
>> +	struct ion_allocation_data allocation;
>> +	struct ion_handle_data handle;
>> +	struct ion_custom_data custom;
>> +	struct ion_abi_version abi_version;
>> +	struct ion_new_alloc_data allocation2;
>> +	struct ion_usage_id_map id_map;
>> +	struct ion_usage_cnt usage_cnt;
>> +	struct ion_heap_query query;
>> +};
>> +
>> +static int validate_ioctl_arg(unsigned int cmd, union ion_ioctl_arg *arg)
>> +{
>> +	int ret = 0;
>> +
>> +	switch (cmd) {
>> +	case ION_IOC_ABI_VERSION:
>> +		ret =  arg->abi_version.reserved != 0;
>> +		break;
>> +	case ION_IOC_ALLOC2:
>> +		ret = arg->allocation2.reserved0 != 0;
>> +		ret |= arg->allocation2.reserved1 != 0;
>> +		ret |= arg->allocation2.reserved2 != 0;
>> +		break;
>> +	case ION_IOC_ID_MAP:
>> +		ret = arg->id_map.reserved0 != 0;
>> +		ret |= arg->id_map.reserved1 != 0;
>> +		break;
>> +	case ION_IOC_USAGE_CNT:
>> +		ret = arg->usage_cnt.reserved != 0;
>> +		break;
>> +	case ION_IOC_HEAP_QUERY:
>> +		ret = arg->query.reserved0 != 0;
>> +		ret |= arg->query.reserved1 != 0;
>> +		ret |= arg->query.reserved2 != 0;
>> +		break;
>> +	default:
>> +		break;
>> +	}
>> +	return ret ? -EINVAL : 0;
>> +}
>> +
>>  /* fix up the cases where the ioctl direction bits are incorrect */
>>  static unsigned int ion_ioctl_dir(unsigned int cmd)
>>  {
>> @@ -42,14 +85,7 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>  	struct ion_handle *cleanup_handle = NULL;
>>  	int ret = 0;
>>  	unsigned int dir;
>> -
>> -	union {
>> -		struct ion_fd_data fd;
>> -		struct ion_allocation_data allocation;
>> -		struct ion_handle_data handle;
>> -		struct ion_custom_data custom;
>> -		struct ion_abi_version abi_version;
>> -	} data;
>> +	union ion_ioctl_arg data;
>>
>>  	dir = ion_ioctl_dir(cmd);
>>
>> @@ -60,7 +96,12 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>  		if (copy_from_user(&data, (void __user *)arg, _IOC_SIZE(cmd)))
>>  			return -EFAULT;
>>
>> +	ret = validate_ioctl_arg(cmd, &data);
>> +	if (ret)
>> +		return ret;
>> +
>>  	switch (cmd) {
>> +	/* Old ioctl */
>
> I can see the value of this comment, given ION_IOC_ALLOC2, but not for the other cases.
>
>>  	case ION_IOC_ALLOC:
>>  	{
>>  		struct ion_handle *handle;
>> @@ -77,6 +118,7 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>  		cleanup_handle = handle;
>>  		break;
>>  	}
>> +	/* Old ioctl */
>>  	case ION_IOC_FREE:
>>  	{
>>  		struct ion_handle *handle;
>> @@ -92,6 +134,7 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>  		mutex_unlock(&client->lock);
>>  		break;
>>  	}
>> +	/* Old ioctl */
>>  	case ION_IOC_SHARE:
>>  	case ION_IOC_MAP:
>>  	{
>> @@ -106,6 +149,7 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>  			ret = data.fd.fd;
>>  		break;
>>  	}
>> +	/* Old ioctl */
>>  	case ION_IOC_IMPORT:
>>  	{
>>  		struct ion_handle *handle;
>> @@ -117,11 +161,13 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>  			data.handle.handle = handle->id;
>>  		break;
>>  	}
>> +	/* Old ioctl */
>>  	case ION_IOC_SYNC:
>>  	{
>>  		ret = ion_sync_for_device(client, data.fd.fd);
>>  		break;
>>  	}
>> +	/* Old ioctl */
>>  	case ION_IOC_CUSTOM:
>>  	{
>>  		if (!dev->custom_ioctl)
>> @@ -135,6 +181,53 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>>  		data.abi_version.abi_version = ION_ABI_VERSION;
>>  		break;
>>  	}
>> +	case ION_IOC_ALLOC2:
>> +	{
>> +		struct ion_handle *handle;
>> +
>> +		handle = ion_alloc2(client, data.allocation2.len,
>> +					data.allocation2.align,
>> +					data.allocation2.usage_id,
>> +					data.allocation2.flags);
>> +		if (IS_ERR(handle))
>> +			return PTR_ERR(handle);
>> +
>> +		if (data.allocation2.flags & ION_FLAG_NO_HANDLE) {
>> +			data.allocation2.fd = ion_share_dma_buf_fd(client,
>> +								handle);
>> +			ion_handle_put(handle);
>> +			if (data.allocation2.fd < 0)
>> +				ret = data.allocation2.fd;
>> +		} else {
>> +			data.allocation2.handle = handle->id;
>> +
>> +			cleanup_handle = handle;
>> +		}
>> +		break;
>> +	}
>> +	case ION_IOC_ID_MAP:
>> +	{
>> +		ret = ion_map_usage_ids(client,
>> +				(unsigned int __user *)data.id_map.usage_ids,
>> +				data.id_map.cnt);
>> +		if (ret > 0)
>> +			data.id_map.new_id = ret;
>> +		break;
>> +	}
>> +	case ION_IOC_USAGE_CNT:
>> +	{
>> +		down_read(&client->dev->lock);
>> +		data.usage_cnt.cnt = client->dev->heap_cnt;
>> +		up_read(&client->dev->lock);
>> +		break;
>> +	}
>> +	case ION_IOC_HEAP_QUERY:
>> +	{
>> +		ret = ion_query_heaps(client,
>> +				(struct ion_heap_data __user *)data.query.heaps,
>> +				data.query.cnt);
>> +		break;
>> +	}
>>  	default:
>>  		return -ENOTTY;
>>  	}
>> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
>> index 129707f..c096cb9 100644
>> --- a/drivers/staging/android/ion/ion.c
>> +++ b/drivers/staging/android/ion/ion.c
>> @@ -459,6 +459,48 @@ static struct ion_handle *__ion_alloc(struct ion_client *client, size_t len,
>>  	return handle;
>>  }
>>
>> +struct ion_handle *ion_alloc2(struct ion_client *client, size_t len,
>> +				size_t align, unsigned int usage_id,
>> +				unsigned int flags)
>> +{
>> +	struct ion_device *dev = client->dev;
>> +	struct ion_heap *heap;
>> +	struct ion_handle *handle = ERR_PTR(-ENODEV);
>> +
>> +	down_read(&dev->lock);
>> +	heap = idr_find(&dev->idr, usage_id);
>> +	if (!heap) {
>> +		handle = ERR_PTR(-EINVAL);
>> +		goto out;
>> +	}
>> +
>> +	if (heap->type == ION_USAGE_ID_MAP) {
>> +		int i;
>> +
>> +		for (i = 0; i < heap->fallback_cnt; i++){
>> +			heap = idr_find(&dev->idr, heap->fallbacks[i]);
>> +			if (!heap)
>> +				continue;
>> +
>> +			/* Don't recurse for now? */
>> +			if (heap->type == ION_USAGE_ID_MAP)
>> +				continue;
>> +
>> +			handle =  __ion_alloc(client, len, align, heap, flags);
>> +			if (IS_ERR(handle))
>> +				continue;
>> +			else
>> +				break;
>> +		}
>> +	} else {
>> +		handle = __ion_alloc(client, len, align, heap, flags);
>> +	}
>> +out:
>> +	up_read(&dev->lock);
>> +	return handle;
>> +}
>> +EXPORT_SYMBOL(ion_alloc2);
>> +
>>  struct ion_handle *ion_alloc(struct ion_client *client, size_t len,
>>  				size_t align, unsigned int heap_mask,
>>  				unsigned int flags)
>> @@ -1243,6 +1285,55 @@ int ion_sync_for_device(struct ion_client *client, int fd)
>>  	return 0;
>>  }
>>
>> +struct ion_query_data {
>> +	struct ion_heap_data __user *buffer;
>> +	int cnt;
>> +	int max_cnt;
>> +};
>> +
>> +int __ion_query(int id, void *p, void *data)
>> +{
>> +	struct ion_heap *heap = p;
>> +	struct ion_query_data *query = data;
>> +	struct ion_heap_data hdata = {0};
>> +
>> +	if (query->cnt >= query->max_cnt)
>> +		return -ENOSPC;
>> +
>> +	strncpy(hdata.name, heap->name, 20);
>> +	hdata.name[sizeof(hdata.name) - 1] = '\0';
>> +	hdata.type = heap->type;
>> +	hdata.usage_id = heap->id;
>> +
>> +	return copy_to_user(&query->buffer[query->cnt++], &hdata, sizeof(hdata));
>> +}
>> +
>> +int ion_query_heaps(struct ion_client *client,
>> +		struct ion_heap_data __user *buffer,
>> +		int cnt)
>> +{
>> +	struct ion_device *dev = client->dev;
>> +	struct ion_query_data data;
>> +	int ret;
>> +
>> +	data.buffer = buffer;
>> +	data.cnt = 0;
>> +	data.max_cnt = cnt;
>> +
>> +	down_read(&dev->lock);
>> +	if (data.max_cnt < 0 || data.max_cnt > dev->heap_cnt) {
>> +		ret = -EINVAL;
>> +		goto out;
>> +	}
>> +	ret = idr_for_each(&dev->idr, __ion_query, &data);
>> +out:
>> +	up_read(&dev->lock);
>> +
>> +	return ret;
>> +}
>> +
>> +
>> +
>>  static int ion_release(struct inode *inode, struct file *file)
>>  {
>>  	struct ion_client *client = file->private_data;
>> @@ -1407,13 +1498,69 @@ static int debug_shrink_get(void *data, u64 *val)
>>  DEFINE_SIMPLE_ATTRIBUTE(debug_shrink_fops, debug_shrink_get,
>>  			debug_shrink_set, "%llu\n");
>>
>> +int ion_map_usage_ids(struct ion_client *client,
>> +			unsigned int __user *usage_ids,
>> +			int cnt)
>> +{
>> +	struct ion_heap *heap = kzalloc(sizeof(*heap), GFP_KERNEL);
>> +	unsigned int *fallbacks;
>> +	int i;
>> +	int ret;
>> +
>> +	if (!heap)
>> +		return -ENOMEM;
>> +
>> +	fallbacks = kzalloc(sizeof(unsigned int)*cnt, GFP_KERNEL);
>> +	if (!fallbacks) {
>> +		ret = -ENOMEM;
>> +		goto out1;
>> +	}
>> +
>> +	ret = copy_from_user(fallbacks, usage_ids, sizeof(unsigned int)*cnt);
>> +	if (ret)
>> +		goto out2;
>> +
>> +	down_read(&client->dev->lock);
>> +	for (i = 0; i < cnt; i++) {
>> +		if (idr_find(&client->dev->idr, fallbacks[i]) == NULL) {
>> +			ret = -EINVAL;
>> +			goto out3;
>> +		}
>> +	}
>> +	up_read(&client->dev->lock);
>> +
>> +	/*
>> +	 * This is a racy check since the lock is dropped before the heap
>> +	 * is actually added. It's okay though because ids are never actually
>> +	 * deleted. Worst case some user gets an error back and an indication
>> +	 * to fix races in their code.
>> +	 */
>> +
>> +	heap->fallbacks = fallbacks;
>> +	heap->fallback_cnt = cnt;
>> +	heap->type = ION_USAGE_ID_MAP;
>> +	heap->id = ION_DYNAMIC_HEAP_ASSIGN;
>> +	ion_device_add_heap(client->dev, heap);
>> +	return heap->id;
>> +out3:
>> +	up_read(&client->dev->lock);
>> +out2:
>> +	kfree(fallbacks);
>> +out1:
>> +	kfree(heap);
>> +	return ret;
>> +}
>> +
>>  int ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap)
>>  {
>>  	struct dentry *debug_file;
>>  	int ret;
>>
>> -	if (!heap->ops->allocate || !heap->ops->free || !heap->ops->map_dma ||
>> -	    !heap->ops->unmap_dma) {
>> +	if (heap->type != ION_USAGE_ID_MAP &&
>> +	   (!heap->ops->allocate ||
>> +	    !heap->ops->free ||
>> +	    !heap->ops->map_dma ||
>> +	    !heap->ops->unmap_dma)) {
>>  		pr_err("%s: can not add heap with invalid ops struct.\n",
>>  		       __func__);
>>  		return -EINVAL;
>> @@ -1425,18 +1572,36 @@ int ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap)
>>  	if (heap->flags & ION_HEAP_FLAG_DEFER_FREE)
>>  		ion_heap_init_deferred_free(heap);
>>
>> -	if ((heap->flags & ION_HEAP_FLAG_DEFER_FREE) || heap->ops->shrink)
>> +	if ((heap->flags & ION_HEAP_FLAG_DEFER_FREE) || (heap->ops && heap->ops->shrink))
>>  		ion_heap_init_shrinker(heap);
>>
>>  	heap->dev = dev;
>>  	down_write(&dev->lock);
>>
>> -	ret = idr_alloc(&dev->idr, heap, heap->id, heap->id + 1, GFP_KERNEL);
>> -	if (ret < 0 || ret != heap->id) {
>> -		pr_info("%s: Failed to add heap id, expected %d got %d\n",
>> -			__func__, heap->id, ret);
>> -		up_write(&dev->lock);
>> -		return ret < 0 ? ret : -EINVAL;
>> +	if (heap->id == ION_DYNAMIC_HEAP_ASSIGN) {
>> +		ret = idr_alloc(&dev->idr, heap,
>> +				ION_DYNAMIC_HEAP_ASSIGN + 1, 0, GFP_KERNEL);
>
> start = ION_DYNAMIC_HEAP_ASSIGN + 1, end = 0 (aka max) ? Why not end = ION_DYNAMIC_HEAP_ASSIGN + head->fallback_cnt + 1?
>
> At least some comment is warranted explaining the choices here.
>
>> +		if (ret < 0)
>> +			goto out_unlock;
>> +
>> +		heap->id = ret;
>> +	} else {
>> +		ret = idr_alloc(&dev->idr, heap, heap->id, heap->id + 1,
>> +				GFP_KERNEL);
>> +		if (ret < 0 || ret != heap->id) {
>> +			pr_info("%s: Failed to add heap id, expected %d got %d\n",
>> +				__func__, heap->id, ret);
>> +			ret = ret < 0 ? ret : -EINVAL;
>> +			goto out_unlock;
>> +		}
>> +	}
>> +
>> +	if (!heap->name) {
>> +		heap->name = kasprintf(GFP_KERNEL, "heap%d", heap->id);
>> +		if (!heap->name) {
>> +			ret = -ENOMEM;
>> +			goto out_unlock;
>> +		}
>>  	}
>>
>>  	debug_file = debugfs_create_file(heap->name, 0664,
>> @@ -1467,6 +1632,7 @@ int ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap)
>>  		}
>>  	}
>>  	dev->heap_cnt++;
>> +out_unlock:
>>  	up_write(&dev->lock);
>>  	return 0;
>>  }
>> diff --git a/drivers/staging/android/ion/ion_priv.h b/drivers/staging/android/ion/ion_priv.h
>> index b09d751..e03e940 100644
>> --- a/drivers/staging/android/ion/ion_priv.h
>> +++ b/drivers/staging/android/ion/ion_priv.h
>> @@ -255,6 +255,9 @@ struct ion_heap {
>>  	wait_queue_head_t waitqueue;
>>  	struct task_struct *task;
>>
>> +	unsigned int *fallbacks;
>> +	int fallback_cnt;
>> +
>>  	int (*debug_show)(struct ion_heap *heap, struct seq_file *, void *);
>>  };
>>
>> @@ -381,6 +384,10 @@ size_t ion_heap_freelist_shrink(struct ion_heap *heap,
>>  size_t ion_heap_freelist_size(struct ion_heap *heap);
>>
>>
>> +int ion_map_usage_ids(struct ion_client *client,
>> +			unsigned int __user *usage_ids,
>> +			int cnt);
>> +
>>  /**
>>   * functions for creating and destroying the built in ion heaps.
>>   * architectures can add their own custom architecture specific
>> @@ -495,4 +502,12 @@ struct ion_handle *ion_handle_get_by_id(struct ion_client *client,
>>
>>  int ion_handle_put(struct ion_handle *handle);
>>
>> +struct ion_handle *ion_alloc2(struct ion_client *client, size_t len,
>> +				size_t align, unsigned int usage_id,
>> +				unsigned int flags);
>> +
>> +int ion_query_heaps(struct ion_client *client,
>> +		struct ion_heap_data __user *buffer,
>> +		int cnt);
>> +
>>  #endif /* _ION_PRIV_H */
>> diff --git a/drivers/staging/android/uapi/ion.h b/drivers/staging/android/uapi/ion.h
>> index 145005f..d36b4e4 100644
>> --- a/drivers/staging/android/uapi/ion.h
>> +++ b/drivers/staging/android/uapi/ion.h
>> @@ -45,10 +45,17 @@ enum ion_heap_type {
>>  			       * must be last so device specific heaps always
>>  			       * are at the end of this enum
>>  			       */
>> +	ION_USAGE_ID_MAP,
>>  };
>>
>>  #define ION_NUM_HEAP_IDS		(sizeof(unsigned int) * 8)
>>
>> +/*
>> + * This isn't completely random. The old Ion heap ID namespace goes up to
>> + * 32 bits so take the first one after that to use as a dynamic setting
>> + */
>> +#define ION_DYNAMIC_HEAP_ASSIGN		33
>
> Also worth adding that no higher IDs should be defined after this because it's going
> to break the code.
>
>> +
>>  /**
>>   * allocation flags - the lower 16 bits are used by core ion, the upper 16
>>   * bits are reserved for use by the heaps themselves.
>> @@ -65,6 +72,11 @@ enum ion_heap_type {
>>  					 * caches must be managed
>>  					 * manually
>>  					 */
>> +#define ION_FLAG_NO_HANDLE 3		/*
>> +					 * Return only an fd associated with
>> +					 * this buffer and not a handle
>> +					 */
>> +
>>
>>  /**
>>   * DOC: Ion Userspace API
>> @@ -142,6 +154,96 @@ struct ion_abi_version {
>>  	__u32 reserved;
>>  };
>>
>> +/**
>> + * struct ion_new_alloc_data - metadata to/from usersapce allocation v2
>> + * @len:		size of the allocation
>> + * @align:		required alignment of the allocation
>> + * @usage_id:		mapping to heap id to allocate. Will try fallbacks
>> + *			if specified in the heap mapping
>> + * @flags:		flags passed to heap
>> + * @handle:		pointer that will be populated with a cookie to use to
>> + *			refer to this allocation
>> + * @fd:			optionally, may return just an fd with no handle
>> + *			reference
>> + */
>> +struct ion_new_alloc_data {
>> +	__u64 len;
>> +	__u64 align;
>> +	__u32 usage_id;
>> +	__u32 flags;
>> +	/*
>> +	 * I'd like to add a flag to just return the fd instead of just
>> +	 * a handle for those who want to skip the next step.
>> +	 */
>> +	union {
>> +		__u32 fd;
>> +		__u32 handle;
>> +	};
>> +	/*
>> +	 * Allocation has a definite problem of 'creep' so give more than
>> +	 * enough extra bits for expansion
>> +	 */
>> +	__u32 reserved0;
>> +	__u32 reserved1;
>> +	__u32 reserved2;
>> +};
>> +
>> +/**
>> + * struct ion_usage_id_map - metadata to create a new usage map
>> + * @usage_id - userspace allocated array of existing usage ids
>> + * @cnt - number of ids to be mapped
>> + * @new_id - will be populated with the new usage id
>> + */
>> +struct ion_usage_id_map {
>> +	/* Array of usage ids provided by user */
>> +	__u64 usage_ids;
>> +	__u32 cnt;
>> +
>> +	/* Returned on success */
>> +	__u32 new_id;
>> +	/* Fields for future growth */
>> +	__u32 reserved0;
>> +	__u32 reserved1;
>> +};
>> +
>> +/**
>> + * struct ion_usage_cnt - meta data for the count of heaps
>> + * @cnt - returned count of number of heaps present
>> + */
>> +struct ion_usage_cnt {
>> +	__u32 cnt; /* cnt returned */
>> +	__u32 reserved;
>> +};
>> +
>> +/**
>> + * struct ion_heap_data - data about a heap
>> + * @name - first 32 characters of the heap name
>> + * @type - heap type
>> + * @usage_id - usage id for the heap
>> + */
>> +struct ion_heap_data {
>> +	char name[32];
>> +	__u32 type;
>> +	__u32 usage_id;
>> +	__u32 reserved0;
>> +	__u32 reserved1;
>> +	__u32 reserved2;
>> +};
>> +
>> +/**
>> + * struct ion_heap_query - collection of data about all heaps
>> + * @cnt - total number of heaps to be copied
>> + * @heaps - buffer to copy heap data
>> + */
>> +struct ion_heap_query {
>> +	__u32 cnt; /* Total number of heaps to be copied */
>> +	__u64 heaps; /* buffer to be populated */
>> +	__u32 reserved0;
>> +	__u32 reserved1;
>> +	__u32 reserved2;
>> +};
>> +
>> +
>>  #define ION_IOC_MAGIC		'I'
>>
>>  /**
>> @@ -216,5 +318,38 @@ struct ion_abi_version {
>>  #define ION_IOC_ABI_VERSION    _IOR(ION_IOC_MAGIC, 8, \
>>  					struct ion_abi_version)
>>
>> +/**
>> + * DOC: ION_IOC_ALLOC2 - allocate memory via new API
>> + *
>> + * Same concept as ION_IOC_ALLOC except with updated ABI. Can return an fd
>> + * directly in addition to a handle
>> + */
>> +#define ION_IOC_ALLOC2           _IOWR(ION_IOC_MAGIC, 9, \
>> +					struct ion_new_alloc_data)
>> +
>> +/**
>> + * DOC: ION_IOC_ID_MAP - remap an array of heap IDs
>> + *
>> + * Takes an ion_usage_id_map structure populated with information about
>> + * fallback information. Returns a new usage id for use in allocation.
>> + */
>> +#define ION_IOC_ID_MAP         _IOWR(ION_IOC_MAGIC, 10, \
>> +					struct ion_usage_id_map)
>> +/**
>> + * DOC: ION_IOC_USAGE_CNT - returns a count of the number of usage ids
>> + *
>> + * Takes an ion_usage_cnt structure and returns the total number of usage
>> + * ids available.
>> + */
>> +#define ION_IOC_USAGE_CNT      _IOR(ION_IOC_MAGIC, 11, \
>> +					struct ion_usage_cnt)
>> +/**
>> + * DOC: ION_IOC_HEAP_QUERY - information about available heaps
>> + *
>> + * Takes an ion_heap_query structure and populates information about
>> + * availble Ion heaps.
>> + */
>> +#define ION_IOC_HEAP_QUERY     _IOWR(ION_IOC_MAGIC, 12, \
>> +					struct ion_heap_query)
>>
>>  #endif /* _UAPI_LINUX_ION_H */
>> --
>> 2.5.5
>>
>

Thanks for the comments above.

> I know that ION doesn't have any kernel documentation or examples in terms of what userspace
> should do, but after this patchset I feel like adding some text describing how the dynamic
> heap mapping might work on an ideal device that you target is useful.
>

Yes, sounds good. I'll send out some documentation on the next iteration.

> Best regards,
> Liviu
>

Thanks,
Laura

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