On 4/16/22 11:33 AM, Joe Perches wrote:
On Sat, 2022-04-16 at 13:23 -0400, Tom Rix wrote:
In insert_mappable_node(), the parameter node is
cleared late in node's use with memset.
insert_mappable_node() is a singleton, called only
from i915_gem_gtt_prepare() which itself is only
called by i915_gem_gtt_pread() and
i915_gem_gtt_pwrite_fast() where the definition of
node originates.
Instead of using memset, initialize node to 0 at it's
definitions.
trivia: /it's/its/
Only reason _not_ to do this is memset is guaranteed to
zero any padding that might go to userspace.
But it doesn't seem there is any padding anyway nor is
the struct available to userspace.
So this seems fine though it might increase overall code
size a tiny bit.
I do have a caveat: see below:
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
[]
@@ -328,7 +327,6 @@ static struct i915_vma *i915_gem_gtt_prepare(struct
drm_i915_gem_object *obj,
goto err_ww;
} else if (!IS_ERR(vma)) {
node->start = i915_ggtt_offset(vma);
- node->flags = 0;
Why is this unneeded?
node = {} initializes all of node's elements to 0, including this one.
Tom
from: drm_mm_insert_node_in_range which can set node->flags
__set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags);
