[Intel-gfx] drm/i915: Track GEN6 page table usage

[Dan Carpenter]

Hello Ben Widawsky,

The patch 678d96fbb3b5: "drm/i915: Track GEN6 page table usage" from
Mar 16, 2015, leads to the following static checker warning:

	drivers/gpu/drm/i915/i915_gem_gtt.c:363 alloc_pt_single()
	error: passing non negative 1 to ERR_PTR

drivers/gpu/drm/i915/i915_gem_gtt.c
   292  
   293  /**
   294   * i915_dma_map_single() - Create a dma mapping for a page table/dir/etc.
   295   * @px: Page table/dir/etc to get a DMA map for
   296   * @dev:        drm device
   297   *
   298   * Page table allocations are unified across all gens. They always require a
   299   * single 4k allocation, as well as a DMA mapping. If we keep the structs
   300   * symmetric here, the simple macro covers us for every page table type.
   301   *
   302   * Return: 0 if success.
   303   */
   304  #define i915_dma_map_single(px, dev) \
   305          i915_dma_map_page_single((px)->page, (dev), &(px)->daddr)
   306  
   307  static inline int i915_dma_map_page_single(struct page *page,
   308                                             struct drm_device *dev,
   309                                             dma_addr_t *daddr)
   310  {
   311          struct device *device = &dev->pdev->dev;
   312  
   313          *daddr = dma_map_page(device, page, 0, 4096, PCI_DMA_BIDIRECTIONAL);
   314          return dma_mapping_error(device, *daddr);
                       ^^^^^^^^^^^^^^^^^
This function returns 1 on failure but the callers expect a negative
error code.

   315  }

regards,
dan carpenter