staging/android: add flags member to sync ioctl structs

Submitted by Gustavo Padovan on March 3, 2016, 2:37 p.m.

Details

Message ID 1457015837-7609-1-git-send-email-gustavo@padovan.org
State New
Headers show
Series "Series without cover letter" ( rev: 4 ) in DRI devel

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Commit Message

Gustavo Padovan March 3, 2016, 2:37 p.m.
From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

Play safe and add flags member to all structs. So we don't need to
break API or create new IOCTL in the future if new features that requires
flags arises.

v2: check if flags are valid (zero, in this case)

v3: return -EINVAL if flags are not zero'ed

v4: add padding for 64-bit alignment

v5: rebase to use only stacked sync_file_info

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
---
 drivers/staging/android/sync.c      |  8 ++++++++
 drivers/staging/android/uapi/sync.h | 14 ++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

Patch hide | download patch | download mbox

diff --git a/drivers/staging/android/sync.c b/drivers/staging/android/sync.c
index 48ee175..ae81c95 100644
--- a/drivers/staging/android/sync.c
+++ b/drivers/staging/android/sync.c
@@ -445,6 +445,11 @@  static long sync_file_ioctl_merge(struct sync_file *sync_file,
 		goto err_put_fd;
 	}
 
+	if (data.flags || data.pad) {
+		err = -EINVAL;
+		goto err_put_fd;
+	}
+
 	fence2 = sync_file_fdget(data.fd2);
 	if (!fence2) {
 		err = -ENOENT;
@@ -504,6 +509,9 @@  static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 	if (copy_from_user(&info, (void __user *)arg, sizeof(info)))
 		return -EFAULT;
 
+	if (info.flags || info.pad)
+		return -EINVAL;
+
 	/*
 	 * Passing num_fences = 0 means that userspace doesn't want to
 	 * retrieve any sync_fence_info. If num_fences = 0 we skip filling
diff --git a/drivers/staging/android/uapi/sync.h b/drivers/staging/android/uapi/sync.h
index a122bb5..859977c 100644
--- a/drivers/staging/android/uapi/sync.h
+++ b/drivers/staging/android/uapi/sync.h
@@ -16,14 +16,18 @@ 
 
 /**
  * struct sync_merge_data - data passed to merge ioctl
- * @fd2:	file descriptor of second fence
  * @name:	name of new fence
+ * @fd2:	file descriptor of second fence
  * @fence:	returns the fd of the new fence to userspace
+ * @flags:	merge_data flags
+ * @pad:	padding for 64-bit alignment, should always be zero
  */
 struct sync_merge_data {
-	__s32	fd2;
 	char	name[32];
+	__s32	fd2;
 	__s32	fence;
+	__u32	flags;
+	__u32	pad;
 };
 
 /**
@@ -31,12 +35,14 @@  struct sync_merge_data {
  * @obj_name:		name of parent sync_timeline
  * @driver_name:	name of driver implementing the parent
  * @status:		status of the fence 0:active 1:signaled <0:error
+ * @flags:		fence_info flags
  * @timestamp_ns:	timestamp of status change in nanoseconds
  */
 struct sync_fence_info {
 	char	obj_name[32];
 	char	driver_name[32];
 	__s32	status;
+	__u32	flags;
 	__u64	timestamp_ns;
 };
 
@@ -44,14 +50,18 @@  struct sync_fence_info {
  * struct sync_file_info - data returned from fence info ioctl
  * @name:	name of fence
  * @status:	status of fence. 1: signaled 0:active <0:error
+ * @flags:	sync_file_info flags
  * @num_fences	number of fences in the sync_file
+ * @pad:	padding for 64-bit alignment, should always be zero
  * @sync_fence_info: pointer to array of structs sync_fence_info with all
  *		 fences in the sync_file
  */
 struct sync_file_info {
 	char	name[32];
 	__s32	status;
+	__u32	flags;
 	__u32	num_fences;
+	__u32	pad;
 
 	__u64	sync_fence_info;
 };

Comments

On Thu, Mar 03, 2016 at 11:37:17AM -0300, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> 
> Play safe and add flags member to all structs. So we don't need to
> break API or create new IOCTL in the future if new features that requires
> flags arises.
> 
> v2: check if flags are valid (zero, in this case)
> 
> v3: return -EINVAL if flags are not zero'ed
> 
> v4: add padding for 64-bit alignment
> 
> v5: rebase to use only stacked sync_file_info

Why are these vX things here in the changelog?

And you just broke all existing userspace users of this code, why are
you allowed to do that?

not ok...
Hi Greg,

2016-03-03 Greg Kroah-Hartman <gregkh@linuxfoundation.org>:

> On Thu, Mar 03, 2016 at 11:37:17AM -0300, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> > 
> > Play safe and add flags member to all structs. So we don't need to
> > break API or create new IOCTL in the future if new features that requires
> > flags arises.
> > 
> > v2: check if flags are valid (zero, in this case)
> > 
> > v3: return -EINVAL if flags are not zero'ed
> > 
> > v4: add padding for 64-bit alignment
> > 
> > v5: rebase to use only stacked sync_file_info
> 
> Why are these vX things here in the changelog?

There are few people who does this in drm, so I just followed that.  

> 
> And you just broke all existing userspace users of this code, why are
> you allowed to do that?

Because we've discussed this extensively in the last versions of this
patches. Most of the people from CC agreed with it.

We are cleaning up the Android sync and coming up with a better ABI for
it before we de-stage it. Android people agreed with this and we will
patch it.

	Gustavo
2016-03-03 Gustavo Padovan <gustavo.padovan@collabora.co.uk>:

> Hi Greg,
> 
> 2016-03-03 Greg Kroah-Hartman <gregkh@linuxfoundation.org>:
> 
> > On Thu, Mar 03, 2016 at 11:37:17AM -0300, Gustavo Padovan wrote:
> > > From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> > > 
> > > Play safe and add flags member to all structs. So we don't need to
> > > break API or create new IOCTL in the future if new features that requires
> > > flags arises.
> > > 
> > > v2: check if flags are valid (zero, in this case)
> > > 
> > > v3: return -EINVAL if flags are not zero'ed
> > > 
> > > v4: add padding for 64-bit alignment
> > > 
> > > v5: rebase to use only stacked sync_file_info
> > 
> > Why are these vX things here in the changelog?
> 
> There are few people who does this in drm, so I just followed that.  

Anyway, I've sent v7 without the vX things in the changelog.

	Gustavo
On Thu, Mar 03, 2016 at 08:17:14AM -0800, Greg Kroah-Hartman wrote:
> On Thu, Mar 03, 2016 at 11:37:17AM -0300, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> > 
> > Play safe and add flags member to all structs. So we don't need to
> > break API or create new IOCTL in the future if new features that requires
> > flags arises.
> > 
> > v2: check if flags are valid (zero, in this case)
> > 
> > v3: return -EINVAL if flags are not zero'ed
> > 
> > v4: add padding for 64-bit alignment
> > 
> > v5: rebase to use only stacked sync_file_info
> 
> Why are these vX things here in the changelog?

That's how we usually roll in gpu land.
On Thu, Mar 3, 2016 at 11:17 AM, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
> On Thu, Mar 03, 2016 at 11:37:17AM -0300, Gustavo Padovan wrote:
>> From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
>>
>> Play safe and add flags member to all structs. So we don't need to
>> break API or create new IOCTL in the future if new features that requires
>> flags arises.
>>
>> v2: check if flags are valid (zero, in this case)
>>
>> v3: return -EINVAL if flags are not zero'ed
>>
>> v4: add padding for 64-bit alignment
>>
>> v5: rebase to use only stacked sync_file_info
>
> Why are these vX things here in the changelog?
>
> And you just broke all existing userspace users of this code, why are
> you allowed to do that?
>
> not ok...

There are not really any users of this on an upstream kernel yet, so
it makes sense to fix the ABI to something we can live with now,
before that changes.  If we are stuck not breaking ABI with android
stuff pulled into staging as we destage it, then maybe we should be a
*lot* slower at pulling android stuff into staging.  (Ie. if that is
the case, please kick it all out now and we'll re-add things
properly.)

BR,
-R
On Thu, Mar 3, 2016 at 3:54 PM, Rob Clark <robdclark@gmail.com> wrote:
> On Thu, Mar 3, 2016 at 11:17 AM, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
>> On Thu, Mar 03, 2016 at 11:37:17AM -0300, Gustavo Padovan wrote:
>>> From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
>>>
>>> Play safe and add flags member to all structs. So we don't need to
>>> break API or create new IOCTL in the future if new features that requires
>>> flags arises.
>>>
>>> v2: check if flags are valid (zero, in this case)
>>>
>>> v3: return -EINVAL if flags are not zero'ed
>>>
>>> v4: add padding for 64-bit alignment
>>>
>>> v5: rebase to use only stacked sync_file_info
>>
>> Why are these vX things here in the changelog?
>>
>> And you just broke all existing userspace users of this code, why are
>> you allowed to do that?
>>
>> not ok...
>
> There are not really any users of this on an upstream kernel yet, so
> it makes sense to fix the ABI to something we can live with now,
> before that changes.  If we are stuck not breaking ABI with android
> stuff pulled into staging as we destage it, then maybe we should be a
> *lot* slower at pulling android stuff into staging.  (Ie. if that is
> the case, please kick it all out now and we'll re-add things
> properly.)

That all said, I suppose one sensible concession to practicality would
be to burn the old ioctl numbers and pick new ioctl numbers.  At least
this way if someone did manage to take an old android userspace (with
it's various dependencies on other non-upstream SoC specific platform
drivers, etc) and run it on upstream kernel, at least things would
fail in an obvious way.  I could live with this as the
mode-of-operations for fixing up and destaging staging/android stuff.

BR,
-R
On Thu, Mar 03, 2016 at 08:17:14AM -0800, Greg Kroah-Hartman wrote:
> On Thu, Mar 03, 2016 at 11:37:17AM -0300, Gustavo Padovan wrote:
> > From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> > 
> > Play safe and add flags member to all structs. So we don't need to
> > break API or create new IOCTL in the future if new features that requires
> > flags arises.
> > 
> > v2: check if flags are valid (zero, in this case)
> > 
> > v3: return -EINVAL if flags are not zero'ed
> > 
> > v4: add padding for 64-bit alignment
> > 
> > v5: rebase to use only stacked sync_file_info
> 
> Why are these vX things here in the changelog?

Because this is drm and we're special ;-)

> And you just broke all existing userspace users of this code, why are
> you allowed to do that?
> 
> not ok...

We could do fence2.h if you absolutely insist and just forget about the
current one, but that seemed silly. Like Gustavo said, everyone who
actually cares about this stuff is perfectly fine with this. And there's
not a single user of this in upstream anyway, so the only trees we could
break are vendor trees with massive amounts of additional stuff.

Is that reasonable ok for you, or do you insist we do a fences2.h without
going through staging ? ;-)

Thanks, Daniel
Hi Greg,

Allow me to chip in as well.

On 3 March 2016 at 16:17, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> On Thu, Mar 03, 2016 at 11:37:17AM -0300, Gustavo Padovan wrote:
>> From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
>>
>> Play safe and add flags member to all structs. So we don't need to
>> break API or create new IOCTL in the future if new features that requires
>> flags arises.
>>
>> v2: check if flags are valid (zero, in this case)
>>
>> v3: return -EINVAL if flags are not zero'ed
>>
>> v4: add padding for 64-bit alignment
>>
>> v5: rebase to use only stacked sync_file_info
>
> Why are these vX things here in the changelog?
>
> And you just broke all existing userspace users of this code, why are
> you allowed to do that?
>
In all honesty, isn't 'fluid ABI' one of the reasons behind staging ?
That is how it was used by a few drivers in the past, at least. If the
rules have changed and/or Android is special in that regard, we ought
to make it perfectly clear so that people are aware from day 1.

That aside, Android developers were clear that only internal,
downstream components are using this code and they are OK with
breaking the ABI [1]. Gustavo is in the process of rewriting their
tests for upstream inclusion and he'll also update the Android side of
things [2].

With those in mind, I think everything should be safe here. If you
prefer to avoid the ABI break, which approach are you keen on -
reassign new ioctl numbers (Rob suggestion) or use new header fence2.h
(Daniel).

Thank you
Emil

[1] https://lists.freedesktop.org/archives/dri-devel/2016-January/099592.html
[2] https://lists.freedesktop.org/archives/dri-devel/2016-January/099726.html
On Fri, Mar 04, 2016 at 05:40:29PM +0100, Daniel Vetter wrote:
> On Thu, Mar 03, 2016 at 08:17:14AM -0800, Greg Kroah-Hartman wrote:
> > On Thu, Mar 03, 2016 at 11:37:17AM -0300, Gustavo Padovan wrote:
> > > From: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> > > 
> > > Play safe and add flags member to all structs. So we don't need to
> > > break API or create new IOCTL in the future if new features that requires
> > > flags arises.
> > > 
> > > v2: check if flags are valid (zero, in this case)
> > > 
> > > v3: return -EINVAL if flags are not zero'ed
> > > 
> > > v4: add padding for 64-bit alignment
> > > 
> > > v5: rebase to use only stacked sync_file_info
> > 
> > Why are these vX things here in the changelog?
> 
> Because this is drm and we're special ;-)
> 
> > And you just broke all existing userspace users of this code, why are
> > you allowed to do that?
> > 
> > not ok...
> 
> We could do fence2.h if you absolutely insist and just forget about the
> current one, but that seemed silly. Like Gustavo said, everyone who
> actually cares about this stuff is perfectly fine with this. And there's
> not a single user of this in upstream anyway, so the only trees we could
> break are vendor trees with massive amounts of additional stuff.
> 
> Is that reasonable ok for you, or do you insist we do a fences2.h without
> going through staging ? ;-)

Ok, if everyone is ok with this api changing, and will not get mad if it
breaks things, I'm all for fixing this up.

I just want all of your signed-off-by lines on the series please.
Please respond to the v7 of this series and I'll be glad to queue them
up.

thanks,

greg k-h