[PATCH 1/1] drm/mm: optimize rb_hole_addr rbtree search in high addr mode

[kbuild test robot]

Hi Nirmoy,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on drm-intel/for-linux-next]
[also build test WARNING on drm-exynos/exynos-drm-next tegra-drm/drm/tegra/for-next drm-tip/drm-tip linus/master v5.7-rc3 next-20200429]
[cannot apply to drm/drm-next]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Nirmoy-Das/drm-mm-optimize-rb_hole_addr-rbtree-search-in-high-addr-mode/20200429-154950
base:   git://anongit.freedesktop.org/drm-intel for-linux-next
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.1-191-gc51a0382-dirty
        make ARCH=x86_64 allmodconfig
        make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp at intel.com>


sparse warnings: (new ones prefixed by >>)

>> drivers/gpu/drm/drm_mm.c:455:24: sparse: sparse: Using plain integer as NULL pointer

vim +455 drivers/gpu/drm/drm_mm.c

   431	
   432	/**
   433	 * next_hole_high_addr - returns next hole for a DRM_MM_INSERT_HIGH mode request
   434	 * @entry: previously selected drm_mm_node
   435	 * @size: size of the a hole needed for the request
   436	 *
   437	 * This function will verify whether left subtree of @entry has hole big enough
   438	 * to fit the requtested size. If so, it will return previous node of @entry or
   439	 * else it will return parent node of @entry
   440	 *
   441	 * It will also skip the complete left subtree if max_hole_size of that subtree
   442	 * is same as the max_hole_size of the @entry.
   443	 *
   444	 * Returns:
   445	 * previous node of @entry if left subtree of @entry can serve the request or
   446	 * else return parent of @entry
   447	 */
   448	static struct drm_mm_node *
   449	next_hole_high_addr(struct drm_mm_node *entry, u64 size)
   450	{
   451		struct rb_node *rb_node, *left_rb_node, *parent_rb_node;
   452		struct drm_mm_node *left_node;
   453	
   454		if (!entry)
 > 455			return false;
   456	
   457		rb_node = &entry->rb_hole_addr;
   458		if (rb_node->rb_left) {
   459			left_rb_node = rb_node->rb_left;
   460			parent_rb_node = rb_parent(rb_node);
   461			left_node = rb_entry(left_rb_node,
   462					     struct drm_mm_node, rb_hole_addr);
   463			if ((left_node->max_hole_size < size ||
   464			     entry->size == entry->max_hole_size) &&
   465			    parent_rb_node && parent_rb_node->rb_left != rb_node)
   466				return rb_hole_addr_to_node(parent_rb_node);
   467		}
   468	
   469		return rb_hole_addr_to_node(rb_prev(rb_node));
   470	}
   471	

---
0-DAY CI Kernel Test Service, Intel Corporation
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