• Alexander Duyck's avatar
    dma-debug: update DMA debug API to better handle multiple mappings of a buffer · 96e7d7a1
    Alexander Duyck authored
    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: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
    Cc: Joerg Roedel <joro@8bytes.org>
    Reviewed-by: default avatarShuah Khan <shuah.khan@hp.com>
    Tested-by: default avatarShuah Khan <shuah.khan@hp.com>
    Cc: Jakub Kicinski <kubakici@wp.pl>
    Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
dma-debug.c 34.9 KB