From d2435a8e3d683adb9143b9ad3c416ac3a4ca9688 Mon Sep 17 00:00:00 2001
From: Erick Archer <erick.archer@gmx.com>
Date: Thu, 8 Feb 2024 19:13:18 +0100
Subject: [PATCH] drm/i915: Add flex arrays to struct i915_syncmap
The "struct i915_syncmap" uses a dynamically sized set of trailing
elements. It can use an "u32" array or a "struct i915_syncmap *"
array.
So, use the preferred way in the kernel declaring flexible arrays [1].
Because there are two possibilities for the trailing arrays, it is
necessary to declare a union and use the DECLARE_FLEX_ARRAY macro.
The comment can be removed as the union is now clear enough.
Also, avoid the open-coded arithmetic in the memory allocator functions
[2] using the "struct_size" macro.
Moreover, refactor the "__sync_seqno" and "__sync_child" functions due
to now it is possible to use the union members added to the structure.
This way, it is also possible to avoid the open-coded arithmetic in
pointers.
Link: https://www.kernel.org/doc/html/next/process/deprecated.html#zero-length-and-one-element-arrays [1]
Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [2]
Signed-off-by: Erick Archer <erick.archer@gmx.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240208181318.4259-1-erick.archer@gmx.com
---
drivers/gpu/drm/i915/i915_syncmap.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_syncmap.c b/drivers/gpu/drm/i915/i915_syncmap.c
index 60404dbb2e9fa..df6437c37373d 100644
--- a/drivers/gpu/drm/i915/i915_syncmap.c
+++ b/drivers/gpu/drm/i915/i915_syncmap.c
@@ -75,13 +75,10 @@ struct i915_syncmap {
unsigned int height;
unsigned int bitmap;
struct i915_syncmap *parent;
- /*
- * Following this header is an array of either seqno or child pointers:
- * union {
- * u32 seqno[KSYNCMAP];
- * struct i915_syncmap *child[KSYNCMAP];
- * };
- */
+ union {
+ DECLARE_FLEX_ARRAY(u32, seqno);
+ DECLARE_FLEX_ARRAY(struct i915_syncmap *, child);
+ };
};
/**
@@ -99,13 +96,13 @@ void i915_syncmap_init(struct i915_syncmap **root)
static inline u32 *__sync_seqno(struct i915_syncmap *p)
{
GEM_BUG_ON(p->height);
- return (u32 *)(p + 1);
+ return p->seqno;
}
static inline struct i915_syncmap **__sync_child(struct i915_syncmap *p)
{
GEM_BUG_ON(!p->height);
- return (struct i915_syncmap **)(p + 1);
+ return p->child;
}
static inline unsigned int
@@ -200,7 +197,7 @@ __sync_alloc_leaf(struct i915_syncmap *parent, u64 id)
{
struct i915_syncmap *p;
- p = kmalloc(sizeof(*p) + KSYNCMAP * sizeof(u32), GFP_KERNEL);
+ p = kmalloc(struct_size(p, seqno, KSYNCMAP), GFP_KERNEL);
if (unlikely(!p))
return NULL;
@@ -282,7 +279,7 @@ static noinline int __sync_set(struct i915_syncmap **root, u64 id, u32 seqno)
unsigned int above;
/* Insert a join above the current layer */
- next = kzalloc(sizeof(*next) + KSYNCMAP * sizeof(next),
+ next = kzalloc(struct_size(next, child, KSYNCMAP),
GFP_KERNEL);
if (unlikely(!next))
return -ENOMEM;
--
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