Re: [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@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


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