drm/i915/gem: Differentiate oom failures from invalid map types

After a cursory check on the parameters to i915_gem_object_pin_map(),
where we return a precise error, if the backend rejects the mapping we
always return PTR_ERR(-ENOMEM). Let us also return a more precise error
here so we can differentiate between running out of memory and
programming errors (or situations where we may be trying different paths
and looking for an error from an unsupported map).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201127195334.13134-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
index e2c7b2a7895fff25d7c4d13a24112ce95939c3a3..6dad9ea8eaa3cdb639d76aa9e81d296fa9c6f643 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
@@ -238,7 +238,7 @@ unlock:
 
 /* The 'mapping' part of i915_gem_object_pin_map() below */
 static void *i915_gem_object_map_page(struct drm_i915_gem_object *obj,
-               enum i915_map_type type)
+                                     enum i915_map_type type)
 {
        unsigned long n_pages = obj->base.size >> PAGE_SHIFT, i;
        struct page *stack[32], **pages = stack, *page;
@@ -281,7 +281,7 @@ static void *i915_gem_object_map_page(struct drm_i915_gem_object *obj,
                /* Too big for stack -- allocate temporary array instead */
                pages = kvmalloc_array(n_pages, sizeof(*pages), GFP_KERNEL);
                if (!pages)
-                       return NULL;
+                       return ERR_PTR(-ENOMEM);
        }
 
        i = 0;
@@ -294,7 +294,7 @@ static void *i915_gem_object_map_page(struct drm_i915_gem_object *obj,
 }
 
 static void *i915_gem_object_map_pfn(struct drm_i915_gem_object *obj,
-               enum i915_map_type type)
+                                    enum i915_map_type type)
 {
        resource_size_t iomap = obj->mm.region->iomap.base -
                obj->mm.region->region.start;
@@ -305,13 +305,13 @@ static void *i915_gem_object_map_pfn(struct drm_i915_gem_object *obj,
        void *vaddr;
 
        if (type != I915_MAP_WC)
-               return NULL;
+               return ERR_PTR(-ENODEV);
 
        if (n_pfn > ARRAY_SIZE(stack)) {
                /* Too big for stack -- allocate temporary array instead */
                pfns = kvmalloc_array(n_pfn, sizeof(*pfns), GFP_KERNEL);
                if (!pfns)
-                       return NULL;
+                       return ERR_PTR(-ENOMEM);
        }
 
        i = 0;
@@ -349,8 +349,10 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
                        GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));
 
                        err = ____i915_gem_object_get_pages(obj);
-                       if (err)
-                               goto err_unlock;
+                       if (err) {
+                               ptr = ERR_PTR(err);
+                               goto out_unlock;
+                       }
 
                        smp_mb__before_atomic();
                }
@@ -362,7 +364,7 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
        ptr = page_unpack_bits(obj->mm.mapping, &has_type);
        if (ptr && has_type != type) {
                if (pinned) {
-                       err = -EBUSY;
+                       ptr = ERR_PTR(-EBUSY);
                        goto err_unpin;
                }
 
@@ -374,15 +376,13 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
        if (!ptr) {
                if (GEM_WARN_ON(type == I915_MAP_WC &&
                                !static_cpu_has(X86_FEATURE_PAT)))
-                       ptr = NULL;
+                       ptr = ERR_PTR(-ENODEV);
                else if (i915_gem_object_has_struct_page(obj))
                        ptr = i915_gem_object_map_page(obj, type);
                else
                        ptr = i915_gem_object_map_pfn(obj, type);
-               if (!ptr) {
-                       err = -ENOMEM;
+               if (IS_ERR(ptr))
                        goto err_unpin;
-               }
 
                obj->mm.mapping = page_pack_bits(ptr, type);
        }
@@ -393,8 +393,6 @@ out_unlock:
 
 err_unpin:
        atomic_dec(&obj->mm.pages_pin_count);
-err_unlock:
-       ptr = ERR_PTR(err);
        goto out_unlock;
 }