[Intel-gfx] [PATCH] drm/i915/gt: Onion unwind for scratch page allocation failure

[Chris Wilson]

In switching to using objects for our ppGTT scratch pages, care was not
taken to avoid trying to unref NULL objects on failure. And for gen6
ppGTT, it appears we forgot entirely to unwind after a partial allocation
failure.

Fixes: 89351925a477 ("drm/i915/gt: Switch to object allocations for page directories")
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld at intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
---
 drivers/gpu/drm/i915/gt/gen6_ppgtt.c | 18 ++++++++++++------
 drivers/gpu/drm/i915/gt/gen8_ppgtt.c |  3 ++-
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
index c0d17f87b00f..680bd9442eb0 100644
--- a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
+++ b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
@@ -239,18 +239,24 @@ static int gen6_ppgtt_init_scratch(struct gen6_ppgtt *ppgtt)
 			       I915_CACHE_NONE, PTE_READ_ONLY);
 
 	vm->scratch[1] = vm->alloc_pt_dma(vm, I915_GTT_PAGE_SIZE_4K);
-	if (IS_ERR(vm->scratch[1]))
-		return PTR_ERR(vm->scratch[1]);
+	if (IS_ERR(vm->scratch[1])) {
+		ret = PTR_ERR(vm->scratch[1]);
+		goto err_scratch0;
+	}
 
 	ret = pin_pt_dma(vm, vm->scratch[1]);
-	if (ret) {
-		i915_gem_object_put(vm->scratch[1]);
-		return ret;
-	}
+	if (ret)
+		goto err_scratch1;
 
 	fill32_px(vm->scratch[1], vm->scratch[0]->encode);
 
 	return 0;
+
+err_scratch1:
+	i915_gem_object_put(vm->scratch[1]);
+err_scratch0:
+	i915_gem_object_put(vm->scratch[0]);
+	return ret;
 }
 
 static void gen6_ppgtt_free_pd(struct gen6_ppgtt *ppgtt)
diff --git a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
index b236aa046f91..a37c968ef8f7 100644
--- a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
+++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
@@ -607,7 +607,8 @@ static int gen8_init_scratch(struct i915_address_space *vm)
 	return 0;
 
 free_scratch:
-	free_scratch(vm);
+	while (i--)
+		i915_gem_object_put(vm->scratch[i]);
 	return -ENOMEM;
 }
 
-- 
2.20.1