drm/i915: Clear execbuf's vma backpointer upon release

commit 2889caa92321 ("drm/i915: Eliminate lots of iterations over the
execobjects array") jiggled around the error handling and replace a test
that we cleaned up properly after ourselves with an assertion. That
assertion failed because in the release function (moments after the
assertion) we were indeed forgetting to mark the vma as cleared. The
consequence was when testing an invalid relocation address, we would try
to release the vma twice (following the couple of attempts to verify the
address) and on the second release notice that the first release was
incomplete.

Testcase: igt/gem_reloc_overflow/invalid-address
Fixes: 2889caa92321 ("drm/i915: Eliminate lots of iterations over the execobjects array")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170622104722.2583-1-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
(cherry picked from commit 51d05e1b29676a0425749a1533b87e3ad3c6f176)
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index a23a1c3503c8d0c6267e4bfa66587830583e0341..9337446f10682db82fff2fca76b7a4bd6cef2149 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -878,6 +878,7 @@ static void eb_release_vmas(const struct i915_execbuffer *eb)
 
                GEM_BUG_ON(vma->exec_entry != entry);
                vma->exec_entry = NULL;
+               __exec_to_vma(entry) = 0;
 
                if (entry->flags & __EXEC_OBJECT_HAS_PIN)
                        __eb_unreserve_vma(vma, entry);