[PATCH 0/2] Drop SCSI core dev->dma_mask check

[John Garry <john.g.garry@oracle.com>]

In commit be8fcd4a8217 ("scsi: sas: Skip opt_sectors when DMA reports no
real optimization hint"), the check for dev->dma_mask prior to calling
dma_opt_mapping_size() was dropped.

However, it is not safe to do so, as dma_opt_mapping_size() ->
dma_max_mapping_size() may try to dereference dev->dma_mask.

We just don't hit such a path as no SCSI HBA driver which has
dev->dma_mask unset would use the SAS transport.

Fix that issue by adding a dev->dma_mask check in
dma_max_mapping_size().

The dev->dma_mask check in scsi_add_host_with_dma() can then be also
dropped.

John Garry (2):
  dma-mapping: make dma_max_mapping_size() return 0 for no DMA
    capability
  scsi: core: Drop dev->dma_mask check in evaluating max_sectors

 drivers/scsi/hosts.c | 6 ++----
 kernel/dma/mapping.c | 3 +++
 2 files changed, 5 insertions(+), 4 deletions(-)

-- 
2.43.7