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    SubjectRe: [PATCHv2 4/4] staging: android: ion: Add ioctl to query available heaps
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    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@redhat.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.

    >
    >
    >> 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
    >

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