linux-kernel - [PATCH 2/3] gpu: drm: dead code elimination

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Date:   Wed, 18 Dec 2019 11:50:00 +0800
From:   Pan Zhang <zhangpan26@...wei.com>
To:     <zhangpan26@...wei.com>, <hushiyuan@...wei.com>,
        <alexander.deucher@....com>, <christian.koenig@....com>,
        <David1.Zhou@....com>, <airlied@...ux.ie>, <daniel@...ll.ch>,
        <ray.huang@....com>, <irmoy.das@....com>, <sam@...nborg.org>
CC:     <amd-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/3] gpu: drm: dead code elimination

this set adds support for removal of gpu drm dead code.

patch2:
`num_entries` is a data of unsigned type(compilers always treat as unsigned int) and SIZE_MAX == ~0,

so there is a impossible condition:
'(num_entries > ((~0) - 56) / 72) => (max(0-u32) > 256204778801521549)'.

Signed-off-by: Pan Zhang <zhangpan26@...wei.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
index 85b0515..10a7f30 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
@@ -71,10 +71,6 @@ int amdgpu_bo_list_create(struct amdgpu_device *adev, struct drm_file *filp,
 	unsigned i;
 	int r;
 
-	if (num_entries > (SIZE_MAX - sizeof(struct amdgpu_bo_list))
-				/ sizeof(struct amdgpu_bo_list_entry))
-		return -EINVAL;
-
 	size = sizeof(struct amdgpu_bo_list);
 	size += num_entries * sizeof(struct amdgpu_bo_list_entry);
 	list = kvmalloc(size, GFP_KERNEL);
-- 
2.7.4