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SubjectRe: [PATCH v2 2/2] staging: ion: create one device entry per heap
2017-09-19 13:02 GMT+02:00 Greg KH <gregkh@linuxfoundation.org>:
> On Tue, Sep 19, 2017 at 12:25:38PM +0200, 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.
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
>> ---
>> drivers/staging/android/ion/ion-ioctl.c | 11 +++++++++--
>> drivers/staging/android/ion/ion.c | 23 +++++++++++++++++------
>> drivers/staging/android/ion/ion.h | 10 +++++++---
>> 3 files changed, 33 insertions(+), 11 deletions(-)
>>
>> 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..3f8b595 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;
>>
>> @@ -541,11 +543,24 @@ void 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;
>
> No cleanup needed? No reporting an error happened back up the chain?
> Not nice :(

I will change that

>> +
>> spin_lock_init(&heap->free_lock);
>> heap->free_list_size = 0;
>>
>> @@ -595,13 +610,9 @@ 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");
>
> Did you just change the major number for the device node as well?
>
My understanding of alloc_chrdev_region() is that major number is chosen
dynamically but I don't understand the link with device node, sorry.

> Wow, that's a lot of userspace breakage (both major number, and name),
> how did you test this?

I had to write a test by myself:
https://git.linaro.org/people/benjamin.gaignard/ion_test_application.git/log/?h=one_device_per_heap

Laura have tried to push a test VGEM but I believe it hasn't be
accepted yet (I will check)

>
> Have you gotten "upstream" to agree to these changes? We can't take
> these until they think it's ok as well.

Split /dev/ion into multiple nodes is one of the task listed in
staging/android/TODO
file before been able to de-stage ion.

Since it has been a big bang in ion ABI on 4.12 and the fact that
ion.h is still in
staging/android/uapi/ directory I do believe that userland is still unstable.
I hope this kind of patch will help to clarify what is still need to
be done to de-stage ion
even if this patch is NACK-ed we can at least the item from the TODO list.

Benjamin

>
> thanks,
>
> greg k-h

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