[PATCH v2 0/4] dma-buf/sync_file: rework fences on struct sync_file

[Gustavo Padovan]

From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>

Hi all,

This is an attempt to improve fence support on Sync File. The basic idea
is to have only sync_file->fence and store all fences there, either as
normal fences or fence_arrays. That way we can remove some potential
duplication when using fence_array with sync_file: the duplication of the array
of fences and the duplication of fence_add_callback() for all fences.

Now when creating a new sync_file during the merge process sync_file_set_fence()
will set sync_file->fence based on the number of fences for that sync_file. If
there is more than one fence a fence_array is created. One important advantage
approach is that we only add one fence callback now, no matter how many fences
there are in a sync_file - the individual callbacks are added by fence_array.

This patchset also adds sync_file_get_fence() to retrieve fence from a sync_file
file descriptor.

Please review! Thanks!

	Gustavo

---
Changes since PATCH v1 Comments from Chris Wilson)
 - use sizeof(*fence) to reallocate array 
 - fix typo in comments
 - protect num_fences sum against overflows
 - use array->base instead of casting the to struct fence
 - remove ternary if from ops comparison in fence_is_array()
 - add EXPORT_SYMBOL(fence_array_ops)
 
Changes since RFC v2 (Comments from Chris Wilson and Christian KÃnig):
 - struct sync_file lost status member in favor of fence_is_signaled()
 - drop use of fence_array_teardown()
 - use sizeof(*fence) to allocate only an array on fence pointers

Changes since RFC v1 (Comments from Chris Wilson and Christian KÃnig):
 - Not using fence_ops anymore.
 - fence_is_array() was created to differentiate fence from fence_array
 - fence_array_teardown() is now exported and used under fence_is_array()
 - struct sync_file lost num_fences member

Gustavo Padovan (4):
  dma-buf/fence-array: add fence_is_array()
  dma-buf/sync_file: rework fence storage in struct file
  dma-buf/sync_file: add sync_file_get_fence()
  Documentation: add doc for sync_file_get_fence()

 Documentation/sync_file.txt          |  15 +++
 drivers/dma-buf/fence-array.c        |   1 +
 drivers/dma-buf/sync_file.c          | 190 ++++++++++++++++++++++++-----------
 drivers/staging/android/sync_debug.c |  13 ++-
 include/linux/fence-array.h          |  10 ++
 include/linux/sync_file.h            |  18 ++--
 6 files changed, 172 insertions(+), 75 deletions(-)

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2.5.5