[RFC][PATCH 0/6] ion: improved ABI

[Laura Abbott <labbott@redhat.com>]

The ABI for Ion's ioctl interface are a pain to work with. The heap IDs
are a 32-bit non-discoverable namespace that form part of the ABI. There's
no way to determine what ABI version is in use which leads to problems
if the ABI changes or needs to be updated.

This series is a first approach to give a better ABI for Ion. This includes:

- Following the advice in botching-up-ioctls.txt
- Ioctl for ABI version
- Dynamic assignment of heap ids
- queryable heap ids
- Runtime mapping of heap ids, including fallbacks. This avoids the need to
  encode the fallbacks as an ABI.

I'm most interested in feedback if this ABI is actually an improvement and
usable. The heap id map/query interface seems error prone but I didn't have
a cleaner solution. There aren't any kernel APIs for the new features as the
focus was on a userspace API but I anticipate that following easily once
the userspace API is established.


Thanks,
Laura

P.S. Not to turn this into a bike shedding session but if you have suggestions
for a name for this framework other than Ion I would be interested to hear
them. Too many other things are already named Ion.

Laura Abbott (6):
  staging: android: ion: return error value for ion_device_add_heap
  staging: android: ion: Switch to using an idr to manage heaps
  staging: android: ion: Drop heap type masks
  staging: android: ion: Pull out ion ioctls to a separate file
  staging: android: ion: Add an ioctl for ABI checking
  staging: android: ion: Introduce new ioctls for dynamic heaps

 drivers/staging/android/ion/Makefile    |   3 +-
 drivers/staging/android/ion/ion-ioctl.c | 243 ++++++++++++++++++
 drivers/staging/android/ion/ion.c       | 438 ++++++++++++++++----------------
 drivers/staging/android/ion/ion_priv.h  | 109 +++++++-
 drivers/staging/android/uapi/ion.h      | 164 +++++++++++-
 5 files changed, 728 insertions(+), 229 deletions(-)
 create mode 100644 drivers/staging/android/ion/ion-ioctl.c

-- 
2.5.5