Re: [PATCHv2 4/4] staging: android: ion: Add ioctl to query available heaps

[Laura Abbott]

On 09/01/2016 11:14 PM, Greg Kroah-Hartman wrote:
> On Thu, Sep 01, 2016 at 03:40:44PM -0700, Laura Abbott wrote:
> > Ion clients currently lack a good method to determine what
> > heaps are available and what ids they map to. This leads
> > to tight coupling between user and kernel space and headaches.
> > Add a query ioctl to let userspace know the availability of
> > heaps.
> >
> > Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
> > ---
> >  drivers/staging/android/ion/ion-ioctl.c | 11 +++++++++
> >  drivers/staging/android/ion/ion.c       | 44 +++++++++++++++++++++++++++++++++
> >  drivers/staging/android/ion/ion_priv.h  |  3 +++
> >  drivers/staging/android/uapi/ion.h      | 39 +++++++++++++++++++++++++++++
> >  4 files changed, 97 insertions(+)
> >
> > diff --git a/drivers/staging/android/ion/ion-ioctl.c b/drivers/staging/android/ion/ion-ioctl.c
> > index 53b9520..e76d517 100644
> > --- a/drivers/staging/android/ion/ion-ioctl.c
> > +++ b/drivers/staging/android/ion/ion-ioctl.c
> > @@ -28,6 +28,7 @@ union ion_ioctl_arg {
> >  	struct ion_handle_data handle;
> >  	struct ion_custom_data custom;
> >  	struct ion_abi_version abi_version;
> > +	struct ion_heap_query query;
> >  };
> >
> >  static int validate_ioctl_arg(unsigned int cmd, union ion_ioctl_arg *arg)
> > @@ -38,6 +39,11 @@ static int validate_ioctl_arg(unsigned int cmd, union ion_ioctl_arg *arg)
> >  	case ION_IOC_ABI_VERSION:
> >  		ret = arg->abi_version.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;
> >  	}
> > @@ -162,6 +168,11 @@ long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> >  		data.abi_version.abi_version = ION_ABI_VERSION;
> >  		break;
> >  	}
> > +	case ION_IOC_HEAP_QUERY:
> > +	{
> > +		ret = ion_query_heaps(client, &data.query);
> > +		break;
> > +	}
>
> Minor nit, the { } aren't needed here.  Yeah, I know the other cases
> have them, but they aren't all needed there either, no need to keep
> copying bad code style :)

Huh, might deserve a checkpatch addition then. Never heard that one before.

> >  	default:
> >  		return -ENOTTY;
> >  	}
> > diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
> > index 975b48f..91b765c 100644
> > --- a/drivers/staging/android/ion/ion.c
> > +++ b/drivers/staging/android/ion/ion.c
> > @@ -1174,6 +1174,49 @@ int ion_sync_for_device(struct ion_client *client, int fd)
> >  	return 0;
> >  }
> >
> > +int ion_query_heaps(struct ion_client *client, struct ion_heap_query *query)
> > +{
> > +	struct ion_device *dev = client->dev;
> > +	struct ion_heap_data __user *buffer =
> > +		(struct ion_heap_data __user *)query->heaps;
>
> Shouldn't query be marked as __user instead of having this cast?

No, the query structure itself is copied into the kernel in ion_ioctl.
The sub field query->heaps is a user pointer which is marked as _u64
for compatability ala botching-ioctls.txt hence the cast.

> > +	int ret = -EINVAL, cnt = 0, max_cnt;
> > +	struct ion_heap *heap;
> > +	struct ion_heap_data hdata;
> > +
> > +	memset(&hdata, 0, sizeof(hdata));
> > +
> > +	down_read(&dev->lock);
> > +	if (!buffer) {
> > +		query->cnt = dev->heap_cnt;
>
> Wait, query is __user?
>
> I think the mixing of user/kernel pointers here isn't quite right, or I
> just really can't figure it out...
>
> And kbuild didn't seem to like this patch either :(
>
> But your first 2 patches are great, I'll queue them up later today.
>
> thanks,
>
> greg k-h