From: Ankitprasad Sharma <ankitprasad.r.sha...@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.

v2: Moved the patch up in the series, added error propagation for
i915_gem_alloc_object too (Chris)

v3: Removed storing of error pointer inside structs, Corrected error
propagation in caller functions (Chris)

v4: Remove assignments inside the predicate (Chris)

v5: Removed unnecessary initializations, updated kerneldoc for
i915_guc_client, corrected missed error pointer handling (Tvrtko)

v6: Use ERR_CAST/temporary variable to avoid storing invalid pointer
in a common field (Chris)

v7: Resolved rebasing conflicts (Ankit)

v8: Removed redundant code (Chris)

v9: Rebase

v10: Rebase, resolve merge conflicts

Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sha...@intel.com>
Reviewed-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c              | 15 ++++----
 drivers/gpu/drm/i915/i915_gem_render_state.c |  7 ++--
 drivers/gpu/drm/i915/i915_gem_stolen.c       | 53 +++++++++++++++-------------
 drivers/gpu/drm/i915/i915_guc_submission.c   | 50 ++++++++++++++++----------
 drivers/gpu/drm/i915/intel_display.c         |  2 +-
 drivers/gpu/drm/i915/intel_fbdev.c           |  2 +-
 drivers/gpu/drm/i915/intel_overlay.c         |  3 +-
 drivers/gpu/drm/i915/intel_pm.c              |  7 ++--
 drivers/gpu/drm/i915/intel_ringbuffer.c      |  4 +--
 9 files changed, 83 insertions(+), 60 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0224969..4d7a135 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -392,19 +392,18 @@ i915_gem_alloc_object_stolen(struct drm_device *dev, 
size_t size)
 
        mutex_lock(&dev->struct_mutex);
        obj = i915_gem_object_create_stolen(dev, size);
-       if (!obj) {
-               mutex_unlock(&dev->struct_mutex);
-               return NULL;
-       }
+       if (IS_ERR(obj))
+               goto out;
 
        /* Always clear fresh buffers before handing to userspace */
        ret = i915_gem_object_clear(obj);
        if (ret) {
                drm_gem_object_unreference(&obj->base);
-               mutex_unlock(&dev->struct_mutex);
-               return NULL;
+               obj = ERR_PTR(ret);
+               goto out;
        }
 
+out:
        mutex_unlock(&dev->struct_mutex);
        return obj;
 }
@@ -439,8 +438,8 @@ i915_gem_create(struct drm_file *file,
                return -EINVAL;
        }
 
-       if (IS_ERR_OR_NULL(obj))
-               return -ENOMEM;
+       if (IS_ERR(obj))
+               return PTR_ERR(obj);
 
        ret = drm_gem_handle_create(file, &obj->base, &handle);
        /* drop reference from allocate - handle holds it now */
diff --git a/drivers/gpu/drm/i915/i915_gem_render_state.c 
b/drivers/gpu/drm/i915/i915_gem_render_state.c
index 7c93327..84d91c9 100644
--- a/drivers/gpu/drm/i915/i915_gem_render_state.c
+++ b/drivers/gpu/drm/i915/i915_gem_render_state.c
@@ -59,8 +59,11 @@ static int render_state_init(struct render_state *so,
                return -EINVAL;
 
        so->obj = i915_gem_object_create(dev_priv->dev, 4096);
-       if (IS_ERR(so->obj))
-               return PTR_ERR(so->obj);
+       if (IS_ERR(so->obj)) {
+               ret = PTR_ERR(so->obj);
+               so->obj = NULL;
+               return ret;
+       }
 
        ret = i915_gem_obj_ggtt_pin(so->obj, 4096, 0);
        if (ret)
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c 
b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 81d5b6b..dcb70c1 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -503,6 +503,7 @@ i915_pages_create_for_stolen(struct drm_device *dev,
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        struct sg_table *st;
        struct scatterlist *sg;
+       int ret;
 
        DRM_DEBUG_DRIVER("offset=0x%x, size=%d\n", offset, size);
        BUG_ON(offset > ggtt->stolen_size - size);
@@ -514,11 +515,12 @@ 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;
@@ -567,18 +569,23 @@ _i915_gem_object_create_stolen(struct drm_device *dev,
                               struct drm_mm_node *stolen)
 {
        struct drm_i915_gem_object *obj;
+       struct sg_table *pages;
 
        obj = i915_gem_object_alloc(dev);
        if (obj == NULL)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
 
        drm_gem_private_object_init(dev, &obj->base, stolen->size);
        i915_gem_object_init(obj, &i915_gem_object_stolen_ops);
 
-       obj->pages = i915_pages_create_for_stolen(dev,
-                                                 stolen->start, stolen->size);
-       if (obj->pages == NULL)
-               goto cleanup;
+       pages = i915_pages_create_for_stolen(dev,
+                                            stolen->start, stolen->size);
+       if (IS_ERR(pages)) {
+               i915_gem_object_free(obj);
+               return ERR_CAST(pages);
+       }
+
+       obj->pages = pages;
 
        obj->get_page.sg = obj->pages->sgl;
        obj->get_page.last = 0;
@@ -590,10 +597,6 @@ _i915_gem_object_create_stolen(struct drm_device *dev,
        obj->cache_level = HAS_LLC(dev) ? I915_CACHE_LLC : I915_CACHE_NONE;
 
        return obj;
-
-cleanup:
-       i915_gem_object_free(obj);
-       return NULL;
 }
 
 struct drm_i915_gem_object *
@@ -605,29 +608,29 @@ i915_gem_object_create_stolen(struct drm_device *dev, u64 
size)
        int ret;
 
        if (!drm_mm_initialized(&dev_priv->mm.stolen))
-               return NULL;
+               return ERR_PTR(-ENODEV);
 
        DRM_DEBUG_KMS("creating stolen object: size=%llx\n", size);
        if (size == 0)
-               return NULL;
+               return ERR_PTR(-EINVAL);
 
        stolen = kzalloc(sizeof(*stolen), GFP_KERNEL);
        if (!stolen)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
 
        ret = i915_gem_stolen_insert_node(dev_priv, stolen, size, 4096);
        if (ret) {
                kfree(stolen);
-               return NULL;
+               return ERR_PTR(ret);
        }
 
        obj = _i915_gem_object_create_stolen(dev, stolen);
-       if (obj)
+       if (!IS_ERR(obj))
                return obj;
 
        i915_gem_stolen_remove_node(dev_priv, stolen);
        kfree(stolen);
-       return NULL;
+       return obj;
 }
 
 struct drm_i915_gem_object *
@@ -644,7 +647,7 @@ 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);
 
        lockdep_assert_held(&dev->struct_mutex);
 
@@ -654,11 +657,11 @@ 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->start = stolen_offset;
        stolen->size = size;
@@ -668,15 +671,15 @@ 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);
                kfree(stolen);
-               return NULL;
+               return obj;
        }
 
        /* Some objects just need physical mem from stolen space */
@@ -715,5 +718,5 @@ i915_gem_object_create_stolen_for_preallocated(struct 
drm_device *dev,
 
 err:
        drm_gem_object_unreference(&obj->base);
-       return NULL;
+       return ERR_PTR(ret);
 }
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c 
b/drivers/gpu/drm/i915/i915_guc_submission.c
index ac72451..6ae4f49 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -598,27 +598,30 @@ int i915_guc_submit(struct drm_i915_gem_request *rq)
  * object needs to be pinned lifetime. Also we must pin it to gtt space other
  * than [0, GUC_WOPCM_TOP) because this range is reserved inside GuC.
  *
- * Return:     A drm_i915_gem_object if successful, otherwise NULL.
+ * Return:     A drm_i915_gem_object if successful, otherwise error pointer.
  */
 static struct drm_i915_gem_object *gem_allocate_guc_obj(struct drm_device *dev,
                                                        u32 size)
 {
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct drm_i915_gem_object *obj;
+       int ret;
 
        obj = i915_gem_object_create(dev, size);
        if (IS_ERR(obj))
-               return NULL;
+               return obj;
 
-       if (i915_gem_object_get_pages(obj)) {
+       ret = i915_gem_object_get_pages(obj);
+       if (ret) {
                drm_gem_object_unreference(&obj->base);
-               return NULL;
+               return ERR_PTR(ret);
        }
 
-       if (i915_gem_obj_ggtt_pin(obj, PAGE_SIZE,
-                       PIN_OFFSET_BIAS | GUC_WOPCM_TOP)) {
+       ret = i915_gem_obj_ggtt_pin(obj, PAGE_SIZE,
+                                   PIN_OFFSET_BIAS | GUC_WOPCM_TOP);
+       if (ret) {
                drm_gem_object_unreference(&obj->base);
-               return NULL;
+               return ERR_PTR(ret);
        }
 
        /* Invalidate GuC TLB to let GuC take the latest updates to GTT. */
@@ -693,7 +696,7 @@ static void guc_client_free(struct drm_device *dev,
  * @ctx:       the context that owns the client (we use the default render
  *             context)
  *
- * Return:     An i915_guc_client object if success, else NULL.
+ * Return:     An i915_guc_client object if success, error pointer on failure.
  */
 static struct i915_guc_client *guc_client_alloc(struct drm_device *dev,
                                                uint32_t priority,
@@ -703,10 +706,11 @@ static struct i915_guc_client *guc_client_alloc(struct 
drm_device *dev,
        struct drm_i915_private *dev_priv = dev->dev_private;
        struct intel_guc *guc = &dev_priv->guc;
        struct drm_i915_gem_object *obj;
+       int ret;
 
        client = kzalloc(sizeof(*client), GFP_KERNEL);
        if (!client)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
 
        client->doorbell_id = GUC_INVALID_DOORBELL_ID;
        client->priority = priority;
@@ -717,13 +721,16 @@ static struct i915_guc_client *guc_client_alloc(struct 
drm_device *dev,
                        GUC_MAX_GPU_CONTEXTS, GFP_KERNEL);
        if (client->ctx_index >= GUC_MAX_GPU_CONTEXTS) {
                client->ctx_index = GUC_INVALID_CTX_ID;
+               ret = -EINVAL;
                goto err;
        }
 
        /* The first page is doorbell/proc_desc. Two followed pages are wq. */
        obj = gem_allocate_guc_obj(dev, GUC_DB_SIZE + GUC_WQ_SIZE);
-       if (!obj)
+       if (IS_ERR(obj)) {
+               ret = PTR_ERR(obj);
                goto err;
+       }
 
        /* We'll keep just the first (doorbell/proc) page permanently kmap'd. */
        client->client_obj = obj;
@@ -744,9 +751,11 @@ static struct i915_guc_client *guc_client_alloc(struct 
drm_device *dev,
                client->proc_desc_offset = (GUC_DB_SIZE / 2);
 
        client->doorbell_id = assign_doorbell(guc, client->priority);
-       if (client->doorbell_id == GUC_INVALID_DOORBELL_ID)
+       if (client->doorbell_id == GUC_INVALID_DOORBELL_ID) {
                /* XXX: evict a doorbell instead */
+               ret = -EINVAL;
                goto err;
+       }
 
        guc_init_proc_desc(guc, client);
        guc_init_ctx_desc(guc, client);
@@ -754,7 +763,8 @@ static struct i915_guc_client *guc_client_alloc(struct 
drm_device *dev,
 
        /* XXX: Any cache flushes needed? General domain mgmt calls? */
 
-       if (host2guc_allocate_doorbell(guc, client))
+       ret = host2guc_allocate_doorbell(guc, client);
+       if (ret)
                goto err;
 
        DRM_DEBUG_DRIVER("new priority %u client %p: ctx_index %u db_id %u\n",
@@ -766,7 +776,7 @@ err:
        DRM_ERROR("FAILED to create priority %u GuC client!\n", priority);
 
        guc_client_free(dev, client);
-       return NULL;
+       return ERR_PTR(ret);
 }
 
 static void guc_create_log(struct intel_guc *guc)
@@ -791,7 +801,7 @@ static void guc_create_log(struct intel_guc *guc)
        obj = guc->log_obj;
        if (!obj) {
                obj = gem_allocate_guc_obj(dev_priv->dev, size);
-               if (!obj) {
+               if (IS_ERR(obj)) {
                        /* logging will be off */
                        i915.guc_log_level = -1;
                        return;
@@ -911,6 +921,7 @@ int i915_guc_submission_init(struct drm_device *dev)
        const size_t poolsize = GUC_MAX_GPU_CONTEXTS * ctxsize;
        const size_t gemsize = round_up(poolsize, PAGE_SIZE);
        struct intel_guc *guc = &dev_priv->guc;
+       int ret;
 
        if (!i915.enable_guc_submission)
                return 0; /* not enabled  */
@@ -919,8 +930,11 @@ int i915_guc_submission_init(struct drm_device *dev)
                return 0; /* already allocated */
 
        guc->ctx_pool_obj = gem_allocate_guc_obj(dev_priv->dev, gemsize);
-       if (!guc->ctx_pool_obj)
-               return -ENOMEM;
+       if (IS_ERR(guc->ctx_pool_obj)) {
+               ret = PTR_ERR(guc->ctx_pool_obj);
+               guc->ctx_pool_obj = NULL;
+               return ret;
+       }
 
        ida_init(&guc->ctx_ids);
 
@@ -941,9 +955,9 @@ int i915_guc_submission_enable(struct drm_device *dev)
        client = guc_client_alloc(dev,
                                  GUC_CTX_PRIORITY_KMD_NORMAL,
                                  dev_priv->kernel_context);
-       if (!client) {
+       if (IS_ERR(client)) {
                DRM_ERROR("Failed to create execbuf guc_client\n");
-               return -ENOMEM;
+               return PTR_ERR(client);
        }
 
        guc->execbuf_client = client;
diff --git a/drivers/gpu/drm/i915/intel_display.c 
b/drivers/gpu/drm/i915/intel_display.c
index 1c700a2..4bbda9c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2495,7 +2495,7 @@ intel_alloc_initial_plane_obj(struct intel_crtc *crtc,
                                                             base_aligned,
                                                             base_aligned,
                                                             size_aligned);
-       if (!obj) {
+       if (IS_ERR(obj)) {
                mutex_unlock(&dev->struct_mutex);
                return false;
        }
diff --git a/drivers/gpu/drm/i915/intel_fbdev.c 
b/drivers/gpu/drm/i915/intel_fbdev.c
index 99e2753..e094005 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -149,7 +149,7 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
         * features. */
        if (size * 2 < ggtt->stolen_usable_size)
                obj = i915_gem_object_create_stolen(dev, size);
-       if (obj == NULL)
+       if (IS_ERR_OR_NULL(obj))
                obj = i915_gem_object_create(dev, size);
        if (IS_ERR(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 eb93f90..3323596 100644
--- a/drivers/gpu/drm/i915/intel_overlay.c
+++ b/drivers/gpu/drm/i915/intel_overlay.c
@@ -1388,10 +1388,11 @@ void intel_setup_overlay(struct drm_i915_private 
*dev_priv)
        reg_bo = NULL;
        if (!OVERLAY_NEEDS_PHYSICAL(dev_priv))
                reg_bo = i915_gem_object_create_stolen(dev_priv->dev, 
PAGE_SIZE);
-       if (reg_bo == NULL)
+       if (IS_ERR_OR_NULL(reg_bo))
                reg_bo = i915_gem_object_create(dev_priv->dev, PAGE_SIZE);
        if (IS_ERR(reg_bo))
                goto out_free;
+
        overlay->reg_bo = reg_bo;
 
        if (OVERLAY_NEEDS_PHYSICAL(dev_priv)) {
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index b6dfd02..eea2804 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5517,10 +5517,13 @@ static void valleyview_setup_pctx(struct 
drm_i915_private *dev_priv)
                                                                      
pcbr_offset,
                                                                      
I915_GTT_OFFSET_NONE,
                                                                      
pctx_size);
+               if (IS_ERR(pctx))
+                       pctx = NULL;
+
                goto out;
        }
 
-       DRM_DEBUG_DRIVER("BIOS didn't set up PCBR, fixing up\n");
+       DRM_DEBUG_DRIVER("BIOS didn't set up PCBR or prealloc failed, fixing 
up\n");
 
        /*
         * From the Gunit register HAS:
@@ -5531,7 +5534,7 @@ static void valleyview_setup_pctx(struct drm_i915_private 
*dev_priv)
         * memory, or any other relevant ranges.
         */
        pctx = i915_gem_object_create_stolen(dev_priv->dev, pctx_size);
-       if (!pctx) {
+       if (IS_ERR(pctx)) {
                DRM_DEBUG("not enough stolen space for PCTX, disabling\n");
                goto out;
        }
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c 
b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 8d35a39..586360b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -2179,7 +2179,7 @@ static int intel_alloc_ringbuffer_obj(struct drm_device 
*dev,
        obj = NULL;
        if (!HAS_LLC(dev))
                obj = i915_gem_object_create_stolen(dev, ringbuf->size);
-       if (obj == NULL)
+       if (IS_ERR_OR_NULL(obj))
                obj = i915_gem_object_create(dev, ringbuf->size);
        if (IS_ERR(obj))
                return PTR_ERR(obj);
@@ -2740,7 +2740,7 @@ int intel_init_render_ring_buffer(struct drm_device *dev)
        engine->hw_id = 0;
        engine->mmio_base = RENDER_RING_BASE;
 
-       if (INTEL_GEN(dev_priv) >= 8) {
+       if (INTEL_INFO(dev)->gen >= 8) {
                if (i915_semaphore_is_enabled(dev_priv)) {
                        obj = i915_gem_object_create(dev, 4096);
                        if (IS_ERR(obj)) {
-- 
1.9.1

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