[v3,2/2] staging: ion: create one device entry per heap

Message ID 1505897105-23721-3-git-send-email-benjamin.gaignard@linaro.org
State New
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Series
  • Untitled series #4268
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Commit Message

Benjamin Gaignard Sept. 20, 2017, 8:45 a.m.
Instead a getting one common device "/dev/ion" for
all the heaps this patch allow to create one device
entry ("/dev/ionX") per heap.
Getting an entry per heap could allow to set security rules
per heap and global ones for all heaps.

Allocation requests will be only allowed if the mask_id
match with device minor.
Query request could be done on any of the devices.
Deivce node major will also change and that may impact init scripts.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
---
version 3:
- change ion_device_add_heap prototype to return a possible error

version 2:
- simplify ioctl check like propose by Dan
- make sure that we don't register more than ION_DEV_MAX heaps

 drivers/staging/android/TODO            |  1 -
 drivers/staging/android/ion/ion-ioctl.c | 11 +++++++++--
 drivers/staging/android/ion/ion.c       | 27 ++++++++++++++++++++-------
 drivers/staging/android/ion/ion.h       | 12 ++++++++----
 4 files changed, 37 insertions(+), 14 deletions(-)

Comments

Laura Abbott Sept. 25, 2017, 6:26 p.m. | #1
On 09/20/2017 01:45 AM, Benjamin Gaignard wrote:
> Instead a getting one common device "/dev/ion" for
> all the heaps this patch allow to create one device
> entry ("/dev/ionX") per heap.
> Getting an entry per heap could allow to set security rules
> per heap and global ones for all heaps.
> 
> Allocation requests will be only allowed if the mask_id
> match with device minor.
> Query request could be done on any of the devices.
> Deivce node major will also change and that may impact init scripts.
> 

We should start Cc linux-api for future changes since we're going
to have more than just /dev/ion.

Thinking about this some more, I think we need to allow backwards
compatibility. It's just not feasible to keep throwing workarounds
into userspace if we can avoid it. I'd propose keeping the old /dev/ion
misc interface available under a Kconfig and then creating the new
split heaps in parallel.

On a somewhat related note, there was some interest in possibly
having a sysfs interface for Ion long term. I don't think this
needs to happen right now but I'd like whatever we do to not
make adding that harder.

Thanks,
Laura
Laura Abbott Sept. 26, 2017, 5:52 p.m. | #2
On 09/25/2017 11:56 PM, Greg KH wrote:
> On Tue, Sep 26, 2017 at 07:09:14AM +0200, Daniel Vetter wrote:
>> On Mon, Sep 25, 2017 at 11:26:27AM -0700, Laura Abbott wrote:
>>> On 09/20/2017 01:45 AM, Benjamin Gaignard wrote:
>>>> Instead a getting one common device "/dev/ion" for
>>>> all the heaps this patch allow to create one device
>>>> entry ("/dev/ionX") per heap.
>>>> Getting an entry per heap could allow to set security rules
>>>> per heap and global ones for all heaps.
>>>>
>>>> Allocation requests will be only allowed if the mask_id
>>>> match with device minor.
>>>> Query request could be done on any of the devices.
>>>> Deivce node major will also change and that may impact init scripts.
>>>>
>>>
>>> We should start Cc linux-api for future changes since we're going
>>> to have more than just /dev/ion.
>>>
>>> Thinking about this some more, I think we need to allow backwards
>>> compatibility. It's just not feasible to keep throwing workarounds
>>> into userspace if we can avoid it. I'd propose keeping the old /dev/ion
>>> misc interface available under a Kconfig and then creating the new
>>> split heaps in parallel.
>>>
>>> On a somewhat related note, there was some interest in possibly
>>> having a sysfs interface for Ion long term. I don't think this
>>> needs to happen right now but I'd like whatever we do to not
>>> make adding that harder.
>>
>> Not sure sysfs is a good idea for allocating buffers. The backlight
>> interface is in sysfs, which defacto makes it a root-only interface.
>> Distros really hate that, because it makes unpriviledged X/wayland really
>> hard to pull of. Passing a device file otoh from logind to the compositor
>> is dead simple (and how X et al get at e.g. the drm/input devices
>> already).
> 
> sysfs is not a good idea for allocating buffers.  We already have some
> out-of-tree drm drivers doing horrid things in sysfs in ways that
> totally abuse that api, and vendors have to do crazy things with selinux
> rules to try to lock it down because of that.  A device node is fine, we
> are used to that for graphics stuff :)
> 
> thanks,
> 
> greg k-h
> 

I wasn't thinking of sysfs for allocation, this was for exposure of
other Ion information that might make more sense than debugfs. Like
I said, this was mostly forward thinking to make sure we aren't
stuck later.

Thanks,
Laura

Patch

diff --git a/drivers/staging/android/TODO b/drivers/staging/android/TODO
index 5f14247..d770ffa 100644
--- a/drivers/staging/android/TODO
+++ b/drivers/staging/android/TODO
@@ -9,7 +9,6 @@  TODO:
 ion/
  - Add dt-bindings for remaining heaps (chunk and carveout heaps). This would
    involve putting appropriate bindings in a memory node for Ion to find.
- - Split /dev/ion up into multiple nodes (e.g. /dev/ion/heap0)
  - Better test framework (integration with VGEM was suggested)
 
 Please send patches to Greg Kroah-Hartman <greg@kroah.com> and Cc:
diff --git a/drivers/staging/android/ion/ion-ioctl.c b/drivers/staging/android/ion/ion-ioctl.c
index e26b786..c8c906c 100644
--- a/drivers/staging/android/ion/ion-ioctl.c
+++ b/drivers/staging/android/ion/ion-ioctl.c
@@ -25,8 +25,11 @@  union ion_ioctl_arg {
 	struct ion_heap_query query;
 };
 
-static int validate_ioctl_arg(unsigned int cmd, union ion_ioctl_arg *arg)
+static int validate_ioctl_arg(struct file *filp,
+			      unsigned int cmd, union ion_ioctl_arg *arg)
 {
+	int mask = 1 << iminor(filp->f_inode);
+
 	switch (cmd) {
 	case ION_IOC_HEAP_QUERY:
 		if (arg->query.reserved0 ||
@@ -34,6 +37,10 @@  static int validate_ioctl_arg(unsigned int cmd, union ion_ioctl_arg *arg)
 		    arg->query.reserved2 )
 			return -EINVAL;
 		break;
+	case ION_IOC_ALLOC:
+		if (!(arg->allocation.heap_id_mask & mask))
+			return -EINVAL;
+		break;
 	default:
 		break;
 	}
@@ -69,7 +76,7 @@  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);
+	ret = validate_ioctl_arg(filp, cmd, &data);
 	if (WARN_ON_ONCE(ret))
 		return ret;
 
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 93e2c90..cc2d381 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -40,6 +40,8 @@ 
 
 #include "ion.h"
 
+#define ION_DEV_MAX 32
+
 static struct ion_device *internal_dev;
 static int heap_id;
 
@@ -537,15 +539,28 @@  static int debug_shrink_get(void *data, u64 *val)
 DEFINE_SIMPLE_ATTRIBUTE(debug_shrink_fops, debug_shrink_get,
 			debug_shrink_set, "%llu\n");
 
-void ion_device_add_heap(struct ion_heap *heap)
+int ion_device_add_heap(struct ion_heap *heap)
 {
 	struct dentry *debug_file;
 	struct ion_device *dev = internal_dev;
+	int ret;
 
 	if (!heap->ops->allocate || !heap->ops->free)
 		pr_err("%s: can not add heap with invalid ops struct.\n",
 		       __func__);
 
+	if (heap_id >= ION_DEV_MAX)
+		return -EBUSY;
+
+	heap->ddev.devt = MKDEV(MAJOR(dev->devt), heap_id);
+	dev_set_name(&heap->ddev, "ion%d", heap_id);
+	device_initialize(&heap->ddev);
+	cdev_init(&heap->chrdev, &ion_fops);
+	heap->chrdev.owner = THIS_MODULE;
+	ret = cdev_device_add(&heap->chrdev, &heap->ddev);
+	if (ret < 0)
+		return ret;
+
 	spin_lock_init(&heap->free_lock);
 	heap->free_list_size = 0;
 
@@ -583,6 +598,8 @@  void ion_device_add_heap(struct ion_heap *heap)
 
 	dev->heap_cnt++;
 	up_write(&dev->lock);
+
+	return 0;
 }
 EXPORT_SYMBOL(ion_device_add_heap);
 
@@ -595,13 +612,9 @@  static int ion_device_create(void)
 	if (!idev)
 		return -ENOMEM;
 
-	idev->dev.minor = MISC_DYNAMIC_MINOR;
-	idev->dev.name = "ion";
-	idev->dev.fops = &ion_fops;
-	idev->dev.parent = NULL;
-	ret = misc_register(&idev->dev);
+	ret = alloc_chrdev_region(&idev->devt, 0, ION_DEV_MAX, "ion");
 	if (ret) {
-		pr_err("ion: failed to register misc device.\n");
+		pr_err("ion: unable to allocate major\n");
 		kfree(idev);
 		return ret;
 	}
diff --git a/drivers/staging/android/ion/ion.h b/drivers/staging/android/ion/ion.h
index 621e5f7..bb8efc5 100644
--- a/drivers/staging/android/ion/ion.h
+++ b/drivers/staging/android/ion/ion.h
@@ -17,6 +17,7 @@ 
 #ifndef _ION_H
 #define _ION_H
 
+#include <linux/cdev.h>
 #include <linux/device.h>
 #include <linux/dma-direction.h>
 #include <linux/kref.h>
@@ -26,7 +27,6 @@ 
 #include <linux/sched.h>
 #include <linux/shrinker.h>
 #include <linux/types.h>
-#include <linux/miscdevice.h>
 
 #include "../uapi/ion.h"
 
@@ -90,13 +90,13 @@  void ion_buffer_destroy(struct ion_buffer *buffer);
 
 /**
  * struct ion_device - the metadata of the ion device node
- * @dev:		the actual misc device
+ * @dev:		the actual device
  * @buffers:		an rb tree of all the existing buffers
  * @buffer_lock:	lock protecting the tree of buffers
  * @lock:		rwsem protecting the tree of heaps and clients
  */
 struct ion_device {
-	struct miscdevice dev;
+	dev_t devt;
 	struct rb_root buffers;
 	struct mutex buffer_lock;
 	struct rw_semaphore lock;
@@ -152,6 +152,8 @@  struct ion_heap_ops {
  * struct ion_heap - represents a heap in the system
  * @node:		rb node to put the heap on the device's tree of heaps
  * @dev:		back pointer to the ion_device
+ * @ddev:		device structure
+ * @chrdev:		associated character device
  * @type:		type of heap
  * @ops:		ops struct as above
  * @flags:		flags
@@ -176,6 +178,8 @@  struct ion_heap_ops {
 struct ion_heap {
 	struct plist_node node;
 	struct ion_device *dev;
+	struct device ddev;
+	struct cdev chrdev;
 	enum ion_heap_type type;
 	struct ion_heap_ops *ops;
 	unsigned long flags;
@@ -212,7 +216,7 @@  bool ion_buffer_fault_user_mappings(struct ion_buffer *buffer);
  * ion_device_add_heap - adds a heap to the ion device
  * @heap:		the heap to add
  */
-void ion_device_add_heap(struct ion_heap *heap);
+int ion_device_add_heap(struct ion_heap *heap);
 
 /**
  * some helpers for common operations on buffers using the sg_table