drm/i915: Manually unwind after a failed request allocation
authorChris Wilson <chris@chris-wilson.co.uk>
Thu, 28 Apr 2016 08:56:48 +0000 (09:56 +0100)
committerChris Wilson <chris@chris-wilson.co.uk>
Thu, 28 Apr 2016 11:17:32 +0000 (12:17 +0100)
commitbfa0120073de10717c02ea42cb0f3d8ada35c43f
tree9bb6ca14829034c366edf78ac238a058ed884460
parent0251a963226de25978920544c6e1f4878d544835
drm/i915: Manually unwind after a failed request allocation

In the next patches, we want to move the work out of freeing the request
and into its retirement (so that we can free the request without
requiring the struct_mutex). This means that we cannot rely on
unreferencing the request to completely teardown the request any more
and so we need to manually unwind the failed allocation. In doing so, we
reorder the allocation in order to make the unwind simple (and ensure
that we don't try to unwind a partial request that may have modified
global state) and so we end up pushing the initial preallocation down
into the engine request initialisation functions where we have the
requisite control over the state of the request.

Moving the initial preallocation into the engine is less than ideal: it
moves logic to handle a specific problem with request handling out of
the common code. On the other hand, it does allow those backends
significantly more flexibility in performing its allocations.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461833819-3991-14-git-send-email-chris@chris-wilson.co.uk
drivers/gpu/drm/i915/i915_gem.c
drivers/gpu/drm/i915/intel_lrc.c
drivers/gpu/drm/i915/intel_ringbuffer.c