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

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Date:   Sat, 3 Sep 2016 14:55:06 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Laura Abbott <labbott@...hat.com>
Cc:     devel@...verdev.osuosl.org, Jon Medhurst <tixy@...aro.org>,
        Android Kernel Team <kernel-team@...roid.com>,
        Jeremy Gebben <jgebben@...eaurora.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Liviu Dudau <Liviu.Dudau@....com>,
        Arve Hjønnevåg <arve@...roid.com>,
        linux-kernel@...r.kernel.org, linaro-mm-sig@...ts.linaro.org,
        Riley Andrews <riandrews@...roid.com>,
        John Stultz <john.stultz@...aro.org>,
        Eun Taik Lee <eun.taik.lee@...sung.com>,
        Bryan Huntsman <bryanh@...eaurora.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Chen Feng <puck.chen@...ilicon.com>,
        Brian Starkey <brian.starkey@....com>
Subject: Re: [PATCHv2 4/4] staging: android: ion: Add ioctl to query
 available heaps

On Fri, Sep 02, 2016 at 01:41:48PM -0700, Laura Abbott wrote:
> 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@...hat.com>
> > > ---
> > >  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.

It's not a checkpatch issue, just a "is this { } even needed" type of an
issue :)

> > >  	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.

Ah, ok.  Messy :)

thanks,

greg k-h