[5/5] drm/i915/gtt: Setup vm callbacks late

Commit Message

Mika Kuoppala Feb. 22, 2017, 4:54 p.m. UTC

If we manage to tangle errorpaths and get call to callbacks,
it is better to defensively keep them as null until object init is
finished so that we get clean null deref on callsite,
instead of more cryptic wreckage with partly initialized vm objects.

Signed-off-by: Mika Kuoppala <[e-mail]>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

Comments

Chris Wilson Feb. 22, 2017, 5:20 p.m. UTC | #1

On Wed, Feb 22, 2017 at 06:54:25PM +0200, Mika Kuoppala wrote:
> If we manage to tangle errorpaths and get call to callbacks,
> it is better to defensively keep them as null until object init is
> finished so that we get clean null deref on callsite,
> instead of more cryptic wreckage with partly initialized vm objects.
> 
> Signed-off-by: Mika Kuoppala <[e-mail]>

Series looks ok, but you opened a can of bikeshed! :)
-Chris

Patch

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 791cb81..77276c9 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -1298,11 +1298,6 @@  static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 		return ret;
 	}
 
-	ppgtt->base.cleanup = gen8_ppgtt_cleanup;
-	ppgtt->base.unbind_vma = ppgtt_unbind_vma;
-	ppgtt->base.bind_vma = ppgtt_bind_vma;
-	ppgtt->debug_dump = gen8_dump_ppgtt;
-
 	/* There are only few exceptions for gen >=6. chv and bxt.
 	 * And we are not sure about the latter so play safe for now.
 	 */
@@ -1317,7 +1312,6 @@  static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 		gen8_initialize_pml4(&ppgtt->base, &ppgtt->pml4);
 
 		ppgtt->switch_mm = gen8_mm_switch_48bit;
-
 		ppgtt->base.allocate_va_range = gen8_ppgtt_alloc_4lvl;
 		ppgtt->base.insert_entries = gen8_ppgtt_insert_4lvl;
 		ppgtt->base.clear_range = gen8_ppgtt_clear_4lvl;
@@ -1326,8 +1320,6 @@  static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 		if (ret)
 			goto free_scratch;
 
-		ppgtt->switch_mm = gen8_mm_switch_32bit;
-
 		if (intel_vgpu_active(dev_priv)) {
 			ret = gen8_preallocate_top_level_pdp(ppgtt);
 			if (ret) {
@@ -1336,6 +1328,7 @@  static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 			}
 		}
 
+		ppgtt->switch_mm = gen8_mm_switch_32bit;
 		ppgtt->base.allocate_va_range = gen8_ppgtt_alloc_3lvl;
 		ppgtt->base.insert_entries = gen8_ppgtt_insert_3lvl;
 		ppgtt->base.clear_range = gen8_ppgtt_clear_3lvl;
@@ -1344,6 +1337,11 @@  static int gen8_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 	if (intel_vgpu_active(dev_priv))
 		gen8_ppgtt_notify_vgt(ppgtt, true);
 
+	ppgtt->base.cleanup = gen8_ppgtt_cleanup;
+	ppgtt->base.unbind_vma = ppgtt_unbind_vma;
+	ppgtt->base.bind_vma = ppgtt_bind_vma;
+	ppgtt->debug_dump = gen8_dump_ppgtt;
+
 	return 0;
 
 free_scratch:
@@ -1787,13 +1785,7 @@  static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 	if (ret)
 		return ret;
 
-	ppgtt->base.clear_range = gen6_ppgtt_clear_range;
-	ppgtt->base.insert_entries = gen6_ppgtt_insert_entries;
-	ppgtt->base.unbind_vma = ppgtt_unbind_vma;
-	ppgtt->base.bind_vma = ppgtt_bind_vma;
-	ppgtt->base.cleanup = gen6_ppgtt_cleanup;
 	ppgtt->base.total = I915_PDES * GEN6_PTES * PAGE_SIZE;
-	ppgtt->debug_dump = gen6_dump_ppgtt;
 
 	gen6_scratch_va_range(ppgtt, 0, ppgtt->base.total);
 	gen6_write_page_range(ppgtt, 0, ppgtt->base.total);
@@ -1804,6 +1796,13 @@  static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 		return ret;
 	}
 
+	ppgtt->base.clear_range = gen6_ppgtt_clear_range;
+	ppgtt->base.insert_entries = gen6_ppgtt_insert_entries;
+	ppgtt->base.unbind_vma = ppgtt_unbind_vma;
+	ppgtt->base.bind_vma = ppgtt_bind_vma;
+	ppgtt->base.cleanup = gen6_ppgtt_cleanup;
+	ppgtt->debug_dump = gen6_dump_ppgtt;
+
 	DRM_DEBUG_DRIVER("Allocated pde space (%lldM) at GTT entry: %llx\n",
 			 ppgtt->node.size >> 20,
 			 ppgtt->node.start / PAGE_SIZE);