[PATCH 5/5] drm/i915: Propagating correct error codes to the userspace

[ankitprasad.r.sharma@intel.com]

From: Ankitprasad Sharma <ankitprasad.r.sharma@intel.com>

Propagating correct error codes to userspace by using ERR_PTR and
PTR_ERR macros for stolen memory based object allocation. We generally
return -ENOMEM to the user whenever there is a failure in object
allocation. This patch helps user to identify the correct reason for the
failure and not just -ENOMEM each time.

Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma@intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c         |  4 ++--
 drivers/gpu/drm/i915/i915_gem_stolen.c  | 39 +++++++++++++++++++--------------
 drivers/gpu/drm/i915/intel_display.c    |  2 +-
 drivers/gpu/drm/i915/intel_fbdev.c      |  2 +-
 drivers/gpu/drm/i915/intel_overlay.c    |  4 ++--
 drivers/gpu/drm/i915/intel_pm.c         |  2 +-
 drivers/gpu/drm/i915/intel_ringbuffer.c |  4 ++--
 7 files changed, 31 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b4c64d6..586610e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -393,9 +393,9 @@ i915_gem_create(struct drm_file *file,
 	if (flags & I915_CREATE_PLACEMENT_STOLEN) {
 		mutex_lock(&dev->struct_mutex);
 		obj = i915_gem_object_create_stolen(dev, size);
-		if (!obj) {
+		if (IS_ERR(obj)) {
 			mutex_unlock(&dev->struct_mutex);
-			return -ENOMEM;
+			return PTR_ERR(obj);
 		}
 
 		/* Always clear fresh buffers before handing to userspace */
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index d3c44cb..84ca15a 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -366,6 +366,7 @@ i915_pages_create_for_stolen(struct drm_device *dev,
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct sg_table *st;
 	struct scatterlist *sg;
+	int ret;
 
 	DRM_DEBUG_DRIVER("offset=0x%x, size=%d\n", offset, size);
 	BUG_ON(offset > dev_priv->gtt.stolen_size - size);
@@ -377,11 +378,12 @@ i915_pages_create_for_stolen(struct drm_device *dev,
 
 	st = kmalloc(sizeof(*st), GFP_KERNEL);
 	if (st == NULL)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
-	if (sg_alloc_table(st, 1, GFP_KERNEL)) {
+	ret = sg_alloc_table(st, 1, GFP_KERNEL);
+	if (ret) {
 		kfree(st);
-		return NULL;
+		return ERR_PTR(ret);
 	}
 
 	sg = st->sgl;
@@ -431,10 +433,11 @@ _i915_gem_object_create_stolen(struct drm_device *dev,
 			       struct i915_stolen_node *stolen)
 {
 	struct drm_i915_gem_object *obj;
+	int ret;
 
 	obj = i915_gem_object_alloc(dev);
 	if (obj == NULL)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	drm_gem_private_object_init(dev, &obj->base, stolen->base.size);
 	i915_gem_object_init(obj, &i915_gem_object_stolen_ops);
@@ -442,8 +445,10 @@ _i915_gem_object_create_stolen(struct drm_device *dev,
 	obj->pages = i915_pages_create_for_stolen(dev,
 						  stolen->base.start,
 						  stolen->base.size);
-	if (obj->pages == NULL)
+	if (IS_ERR(obj->pages)) {
+		ret = PTR_ERR(obj->pages);
 		goto cleanup;
+	}
 
 	i915_gem_object_pin_pages(obj);
 	obj->stolen = stolen;
@@ -458,7 +463,7 @@ _i915_gem_object_create_stolen(struct drm_device *dev,
 
 cleanup:
 	i915_gem_object_free(obj);
-	return NULL;
+	return ERR_PTR(ret);
 }
 
 static bool mark_free(struct drm_i915_gem_object *obj, struct list_head *unwind)
@@ -592,21 +597,21 @@ i915_gem_object_create_stolen(struct drm_device *dev, u64 size)
 	struct i915_stolen_node *stolen;
 
 	if (!drm_mm_initialized(&dev_priv->mm.stolen))
-		return NULL;
+		return ERR_PTR(-ENODEV);
 
 	DRM_DEBUG_KMS("creating stolen object: size=%llx\n", size);
 
 	stolen = stolen_alloc(dev_priv, size);
 	if (IS_ERR(stolen))
-		return NULL;
+		return (void *) stolen;
 
 	obj = _i915_gem_object_create_stolen(dev, stolen);
-	if (obj)
+	if (!IS_ERR(obj))
 		return obj;
 
 	i915_gem_stolen_remove_node(dev_priv, &stolen->base);
 	kfree(stolen);
-	return NULL;
+	return obj;
 }
 
 struct drm_i915_gem_object *
@@ -623,7 +628,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	int ret;
 
 	if (!drm_mm_initialized(&dev_priv->mm.stolen))
-		return NULL;
+		return ERR_PTR(-ENODEV);
 
 	DRM_DEBUG_KMS("creating preallocated stolen object: stolen_offset=%x, gtt_offset=%x, size=%x\n",
 			stolen_offset, gtt_offset, size);
@@ -631,11 +636,11 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	/* KISS and expect everything to be page-aligned */
 	if (WARN_ON(size == 0) || WARN_ON(size & 4095) ||
 	    WARN_ON(stolen_offset & 4095))
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	stolen = kzalloc(sizeof(*stolen), GFP_KERNEL);
 	if (!stolen)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	stolen->base.start = stolen_offset;
 	stolen->base.size = size;
@@ -645,15 +650,15 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	if (ret) {
 		DRM_DEBUG_KMS("failed to allocate stolen space\n");
 		kfree(stolen);
-		return NULL;
+		return ERR_PTR(ret);
 	}
 
 	obj = _i915_gem_object_create_stolen(dev, stolen);
-	if (obj == NULL) {
+	if (IS_ERR(obj)) {
 		DRM_DEBUG_KMS("failed to allocate stolen object\n");
 		i915_gem_stolen_remove_node(dev_priv, &stolen->base);
 		kfree(stolen);
-		return NULL;
+		return obj;
 	}
 
 	/* Some objects just need physical mem from stolen space */
@@ -695,5 +700,5 @@ err_out:
 	i915_gem_stolen_remove_node(dev_priv, &stolen->base);
 	kfree(stolen);
 	drm_gem_object_unreference(&obj->base);
-	return NULL;
+	return ERR_PTR(ret);
 }
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f604ce1..9719f86 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2538,7 +2538,7 @@ intel_alloc_initial_plane_obj(struct intel_crtc *crtc,
 							     base_aligned,
 							     base_aligned,
 							     size_aligned);
-	if (!obj)
+	if (IS_ERR(obj))
 		return false;
 
 	obj->tiling_mode = plane_config->tiling;
diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 96476d7..6f5be31 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -140,7 +140,7 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
 	size = mode_cmd.pitches[0] * mode_cmd.height;
 	size = PAGE_ALIGN(size);
 	obj = i915_gem_object_create_stolen(dev, size);
-	if (obj == NULL)
+	if (IS_ERR(obj))
 		obj = i915_gem_alloc_object(dev, size);
 	if (!obj) {
 		DRM_ERROR("failed to allocate framebuffer\n");
diff --git a/drivers/gpu/drm/i915/intel_overlay.c b/drivers/gpu/drm/i915/intel_overlay.c
index 4445426..d36a650 100644
--- a/drivers/gpu/drm/i915/intel_overlay.c
+++ b/drivers/gpu/drm/i915/intel_overlay.c
@@ -1389,10 +1389,10 @@ void intel_setup_overlay(struct drm_device *dev)
 
 	overlay->dev = dev;
 
-	reg_bo = NULL;
+	reg_bo = ERR_PTR(-ENOMEM);
 	if (!OVERLAY_NEEDS_PHYSICAL(dev))
 		reg_bo = i915_gem_object_create_stolen(dev, PAGE_SIZE);
-	if (reg_bo == NULL)
+	if (IS_ERR(reg_bo))
 		reg_bo = i915_gem_alloc_object(dev, PAGE_SIZE);
 	if (reg_bo == NULL)
 		goto out_free;
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 51f2f91..ba1657f 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5304,7 +5304,7 @@ static void valleyview_setup_pctx(struct drm_device *dev)
 	 * memory, or any other relevant ranges.
 	 */
 	pctx = i915_gem_object_create_stolen(dev, pctx_size);
-	if (!pctx) {
+	if (IS_ERR(pctx)) {
 		DRM_DEBUG("not enough stolen space for PCTX, disabling\n");
 		return;
 	}
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 6e6b8db..74c0b7d 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -2007,10 +2007,10 @@ int intel_alloc_ringbuffer_obj(struct drm_device *dev,
 {
 	struct drm_i915_gem_object *obj;
 
-	obj = NULL;
+	obj = ERR_PTR(-ENOMEM);
 	if (!HAS_LLC(dev))
 		obj = i915_gem_object_create_stolen(dev, ringbuf->size);
-	if (obj == NULL)
+	if (IS_ERR(obj))
 		obj = i915_gem_alloc_object(dev, ringbuf->size);
 	if (obj == NULL)
 		return -ENOMEM;
-- 
1.9.1

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