drm/i915: Fix a use after free, and unbalanced refcounting
When converting from implicitly tracked execlist queue items to ref counted
requests, not all frees of requests were replaced with unrefs, and extraneous
refs/unrefs of contexts were added.
Correct the unbalanced refcount & replace the frees.
Remove a noisy warning when hitting the request creation path.
drm_i915_gem_request and intel_context are both kref reference counted
structures. Upon allocation, drm_i915_gem_request's ref count should be
bumped using kref_init. When a context is assigned to the request,
the context's reference count should be bumped using i915_gem_context_reference.
i915_gem_request_reference will reduce the context reference count when
the request is freed.
Problem introduced in
commit 6d3d8274bc45de4babb62d64562d92af984dd238
Author: Nick Hoath <nicholas.hoath@intel.com>
AuthorDate: Thu Jan 15 13:10:39 2015 +0000
drm/i915: Subsume intel_ctx_submit_request in to drm_i915_gem_request
v2: Added comments explaining how the ctx pointer and the request object should
be ref-counted. Removed noisy warning.
v3: Cleaned up the language used in the commit & the header
description (Thanks David Gordon)
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88652
Signed-off-by: Nick Hoath <nicholas.hoath@intel.com>
Reviewed-by: Thomas Daniel <thomas.daniel@intel.com>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index c26d36c..e5daad5 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2659,8 +2659,7 @@
if (submit_req->ctx != ring->default_context)
intel_lr_context_unpin(ring, submit_req->ctx);
- i915_gem_context_unreference(submit_req->ctx);
- kfree(submit_req);
+ i915_gem_request_unreference(submit_req);
}
/*