dma-debug: update DMA debug API to better handle multiple mappings of a buffer

dma-debug: update DMA debug API to better handle multiple mappings of a buffer

There were reports of the igb driver unmapping buffers without calling
dma_mapping_error.  On closer inspection issues were found in the DMA
debug API and how it handled multiple mappings of the same buffer.

The issue I found is the fact that the debug_dma_mapping_error would only
set the map_err_type to MAP_ERR_CHECKED in the case that the was only one
match for device and device address.  However in the case of non-IOMMU,
multiple addresses existed and as a result it was not setting this field
once a second mapping was instantiated.  I have resolved this by changing
the search so that it instead will now set MAP_ERR_CHECKED on the first
buffer that matches the device and DMA address that is currently in the
state MAP_ERR_NOT_CHECKED.

A secondary side effect of this patch is that in the case of multiple
buffers using the same address only the last mapping will have a valid
map_err_type.  The previous mappings will all end up with map_err_type set
to MAP_ERR_CHECKED because of the dma_mapping_error call in
debug_dma_map_page.  However this behavior may be preferable as it means
you will likely only see one real error per multi-mapped buffer, versus
the current behavior of multiple false errors mer multi-mapped buffer.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Reviewed-by: Shuah Khan <shuah.khan@hp.com>
Tested-by: Shuah Khan <shuah.khan@hp.com>
Cc: Jakub Kicinski <kubakici@wp.pl>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>